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IEEE Standard for High Voltage Gas-Insulated Substations Rated Above 52 kV 

IEEE Power & Energy Society

Sponsored by the Substations and Switchgear Committees 

IEEE 3 Park Avenue New York, NY 10016-5997 USA

IEEE Std C37.122™-2010 (Revision of IEEE Std C37.122-1993)

21 January 2011

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IEEE Std C37.122TM-2010 (Revision of IEEE Std C37.122-1993)

IEEE Standard for High Voltage Gas-Insulated Substations Rated Above 52 kV Sponsor

Substations and Switchgear Committees of the

IEEE Power & Energy Society Approved 30 September 2010

IEEE-SA Standards Board Approved 10 June 2011

American National Standards Institute

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Abstract: The technical requirements for the design, fabrication, testing, and installation of a gasinsulated substations are covered. The parameters to be supplied by the purchaser are set, and the technical requirements for the design, fabrication, testing, and installation details to be furnished by the manufacturer are established. Keywords: IEEE C37.122, gas-insulated metal enclosed switchgear, gas-insulated substation, gas-insulated switchgear, GIS, GIS design, GIS equipment, GIS installation, GIS testing, SF6, sulfur hexafluoride

The IEEE thanks the International Electrotechnical Commission (IEC) for permission to reproduce information from its International Standards IEC 60517 ed 3.0 (1990), IEC 62271-1 ed 1.0 (2007), IEC 62271-102 ed 1.0 (2001), and IEC 62271-203 ed 1.0 (2003). All such extracts are copyright of IEC, Geneva, Switzerland. All rights reserved. Further information on the IEC is available from www.iec.ch. IEC has no responsibility for the placement and context in which the extracts and contents are reproduced by the author, nor is IEC in any way responsible for the other content or accuracy therein. IEC 60517: Subclause: 6.108. IEC 62271-1: Subclauses: 5.6, 5.17, 5.101, 5.102, 6.2.3, 6.2.4, 6.2.5, 6.10.6, and 7.2. IEC 62271-102: Subclauses: 6.103, Annexes A, B, C, D, E, and F. IEC 62271-203: Subclauses: 5.3.101, 5.3.102, 5.3.104, 6.2.9.101, 6.2.9.103, 6.6.1, 6.6.101, 6.6.102, 6.8, 6.101, 6.102, 6.103, 6.104, 6.105, 7.1, 7.101, 7.102, 7.103, 7.104, 10.2, and Annex A. •

The Institute of Electrical and Electronics Engineers, Inc. 3 Park Avenue, New York, NY 10016-5997, USA Copyright © 2011 by the Institute of Electrical and Electronics Engineers, Inc. All rights reserved. Published 21 January 2011. Printed in the United States of America. IEEE is a registered trademark in the U.S. Patent & Trademark Office, owned by the Institute of Electrical and Electronics Engineers, Incorporated. PDF: Print:

ISBN 978-0-7381-6464-9 ISBN 978-0-7381-6465-6

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Introduction This introduction is not part of IEEE Std C37.122-2010, IEEE Standard for High Voltage Gas-Insulated Substations Rated Above 52 kV .

IEEE Std C37.122-1983 was initiated in the early 1970s when the first gas-insulated substations were introduced. The reliability of gas-insulated substations has improved greatly since the first installation in the late 1960s. Utilities have taken advantage of the greater flexibility offered by gas-insulated substations to locate substations closer to load centers with considerable savings in sub-transmission systems costs and reduced system losses. In addition, gas-insulated substations typically offer 25 to 30 years or more of operation before major overhaul is required. To address IEEE policy that IEEE standards should be harmonized with international standards whenever possible a study was conducted by a joint task force of the Substations Committee and IEC. This included a comparison of IEEE and IEC gas-insulated switchgear standards. The recommendations of that task force and joint working group were a series of recommendations to modify both IEEE and IEC gas-insulated switchgear standards to move toward harmonization. This document is a step in that process.

Notice to users Laws and regulations Users of these documents should consult all applicable laws and regulations. Compliance with the provisions of this standard does not imply compliance to any applicable regulatory requirements. Implementers of the standard are responsible for observing or referring to the applicable regulatory requirements. IEEE does not, by the publication of its standards, intend to urge action that is not in compliance with applicable laws, and these documents may not be construed as doing so.

Copyrights This document is copyrighted by the IEEE. It is made available for a wide variety of both public and private uses. These include both use, by reference, in laws and regulations, and use in private selfregulation, standardization, and the promotion of engineering practices and methods. By making this document available for use and adoption by public authorities and private users, the IEEE does not waive any rights in copyright to this document.

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Errata Errata, if any, for this and all other standards can be accessed at the following URL: http://standards.ieee.org/reading/ieee/updates/errata/index.html. Users are encouraged to check this URL for errata periodically.

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Participants At the time this standard was submitted to the IEEE-SA Standards Board for approval, the High Voltage Gas-Insulated Substation Working Group had the following membership: John H. Brunke, Chair Ryan Stone, Vice Chair Arun Arora Paul Barnett George Becker Philip Bolin Markus Etter Arnaud Ficheux Patrick Fitzgerald

Noboru Fujimoto David F. Giegel Peter Grossmann Charles L. Hand Robert Jeanjean Hermann Koch Jorge Marquez Venkatesh Minisandram

Jeffrey Nelson T. W. Olsen Darin Penner Devki Sharma David Solhtalab Brian Withers Peter Wong

The following members of the individual balloting committee voted on this standard. Balloters may have voted for approval, disapproval, or abstention. William J. Ackerman S. Aggarwal Michael Anderson Ficheux Arnaud Stan Arnot Arun Arora Thomas Barnes G. Bartok George Becker W. J. Bill Bergman Wallace Binder William Bloethe Steven Brockschink John H. Brunke Eldridge Byron Chih Chow Jerry Corkran Gary Donner Michael Dood Randall Dotson Denis Dufournet Edgar Dullni Donald Dunn Kenneth Edwards Gary Engmann Markus Etter James Fairris Patrick Fitzgerald Rabiz Foda David Giegel Mietek Glinkowski

Jalal Gohari Edwin Goodwin James Graham Randall Groves Paul Hamer Charles L. Hand David Harris Helmut Heiermeier Steven Hensley Lee Herron Gary Heuston Scott Hietpas Andrew Jones Richard Keil Rameshchandra Ketharaju Hermann Koch Joesph L. Koepfinger Jim Kulchisky Chung-Yiu Lam Stephen Lambert Hua Liu Albert Livshitz G. Luri Jorge Marquez William McBride Daleep Mohla Georges Montillet Kimberly Mosley Dennis Neitzel Jeffrey Nelson Michael S. Newman T. W. Olsen

David Peelo Darin Penner Christopher Petrola Anthony Picagli John Randolph Michael Roberts Tim Rohrer Anne-Marie Sahazizian Bartien Sayogo Dennis Schlender Hamidreza Sharifnia Devki Sharma Gil Shultz Hyeong Sim James Smith Jerry Smith John Spare Ralph Stell Gary Stoedter Ryan Stone David Tepen John Toth Eric Udren John Vergis Waldemar Von Miller Loren Wagenaar Kenneth White Thomas Wier James Wilson Brian Withers Richard York

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When the IEEE-SA Standards Board approved this standard on 30 September 2010, it had the following membership: Robert M. Grow, Chair Richard H. Hulett, Vice Chair Steve M. Mills, Past Chair Judith Gorman, Secretary Karen Bartleson Victor Berman Ted Burse Clint Chaplin Andy Drozd Alexander Gelman Jim Hughes

Young Kyun Kim Joseph L. Koepfinger* John Kulick David J. Law Hung Ling Oleg Logvinov Ted Olsen Ronald C. Petersen

Thomas Prevost Jon Walter Rosdahl Sam Sciacca Mike Seavey Curtis Siller Don Wright

*Member Emeritus

Also included are the following nonvoting IEEE-SA Standards Board liaisons: Satish Aggarwal, NRC Representative Richard DeBlasio, DOE Representative Michael Janezic, NIST Representative Don Messina IEEE Standards Program Manager, Document Development Soo Kim IEEE Standards Program Manager, Technical Program Development

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Contents 1. Overview .................................................................................................................................................... 1 1.1 Scope ................................................................................................................................................... 1 1.2 Normative references ........................................................................................................................... 1 2. Normal (usual) and special (unusual) service conditions ........................................................................... 4 2.1 Normal (usual) service conditions ....................................................................................................... 4 2.2 Special (unusual) service conditions for both indoor and outdoor switchgear .................................... 4 3. Definitions .................................................................................................................................................. 5 4. Ratings ........................................................................................................................................................ 7 4.1 Rated maximum voltage (V) or (Ur) .................................................................................................... 8 4.2 Rated insulation level (Ud, Us, Up)....................................................................................................... 8 4.3 Rated power frequency (fr) ................................................................................................................ 10 4.4 Rated continuous (normal) current and temperature rise ................................................................... 10 4.5 Rated short-time withstand current (Ik) .............................................................................................. 11 4.6 Rated peak withstand current (Ip) ...................................................................................................... 11 4.7 Rated duration of short-circuit (tk) ..................................................................................................... 11 4.8 Rated supply voltage of closing and opening devices and of auxiliary and control circuits (Ua) ...... 11 4.9 Rated supply frequency of closing and opening devices and of auxiliary and control circuits ......... 11 4.10 Rated bus-transfer voltage and current ............................................................................................ 11 4.11 Rated induced current and voltage for grounding switches ............................................................. 12 4.12 Rated short-circuit making current for grounding switches............................................................. 13 5. Design and construction ........................................................................................................................... 13 5.1 Requirements for liquid in switchgear ............................................................................................... 14 5.2 Requirements for gases in switchgear ............................................................................................... 14 5.3 Grounding and bonding of switchgear............................................................................................... 14 5.4 Auxiliary and control equipment ....................................................................................................... 15 5.5 Dependent power operation ............................................................................................................... 15 5.6 Stored energy ..................................................................................................................................... 15 5.7 Independent manual operation ........................................................................................................... 15 5.8 Operation of releases ......................................................................................................................... 15 5.9 Low- and high-pressure interlocking and monitoring devices ........................................................... 16 5.10 Nameplates ...................................................................................................................................... 16 5.11 Interlocking devices ......................................................................................................................... 21 5.12 Position indication ........................................................................................................................... 22 5.13 Degree of protection of enclosures .................................................................................................. 22 5.14 Creepage distance for outdoor insulators ......................................................................................... 22 5.15 Gas and vacuum tightness ............................................................................................................... 22 5.16 Liquid tightness (insulating medium) .............................................................................................. 22 5.17 Flammability .................................................................................................................................... 22 5.18 Electromagnetic compatibility (EMC)............................................................................................. 22 5.19 X-ray emission ................................................................................................................................. 22 5.20 Design of pressurized enclosures..................................................................................................... 22 5.21 Access for operations and maintenance ........................................................................................... 25 5.22 Bus expansion joints ........................................................................................................................ 25 5.23 Insulators, partitions, gas pass through insulators, and operating rods ............................................ 26 5.24 Partitioning ...................................................................................................................................... 27 5.25 Interfaces ......................................................................................................................................... 27 5.26 Seismic requirements ....................................................................................................................... 28 5.27 High-voltage circuit breakers........................................................................................................... 28 viii Copyright © 2011 IEEE. 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5.28 Disconnect switches ........................................................................................................................ 28 5.29 Grounding switches ......................................................................................................................... 29 6. Design tests (type tests) ............................................................................................................................ 30 6.1 General .............................................................................................................................................. 30 6.2 Dielectric tests ................................................................................................................................... 33 6.3 Radio influence voltage (RIV) test .................................................................................................... 38 6.4 Measurement of resistance of circuits ............................................................................................... 38 6.5 Temperature rise tests (continuous current test) ................................................................................ 38 6.6 Short-time withstand current and peak withstand current tests ......................................................... 39 6.7 Verification of the degrees of protection provided by enclosures ..................................................... 40 6.8 Tightness test ..................................................................................................................................... 40 6.9 Electromagnetic compatibility tests ................................................................................................... 40 6.10 Verification of making and breaking capacities .............................................................................. 40 6.11 Mechanical and environmental tests ................................................................................................ 41 6.12 Pressure test on partitions ................................................................................................................ 43 6.13 Test under conditions of arcing due to an internal fault .................................................................. 43 6.14 Insulator tests ................................................................................................................................... 43 6.15 Circuit breaker design tests .............................................................................................................. 44 6.16 Fault-making capability test for high-speed grounding switches .................................................... 44 6.17 Interrupting tests—bus-transfer current switching capability for disconnect switches (special duty only) ................................................................................................................................................. 45 6.18 Interrupting tests—switching of bus charging currents by disconnect switches.............................. 45 6.19 Interrupting tests—induced current switching of grounding switches............................................. 48 6.20 Mechanical tests for disconnect and grounding switches ................................................................ 50 6.21 Operation at the temperature limits for outdoor equipment (if required by user).............................. 50 6.22 Operation under severe ice conditions ............................................................................................. 51 7. Routine testing .......................................................................................................................................... 53 7.1 Dielectric test of main circuit ............................................................................................................ 53 7.2 Tests on auxiliary and control circuits ............................................................................................... 53 7.3 Measurement of the resistance of the main circuit ............................................................................ 54 7.4 Tightness tests.................................................................................................................................... 54 7.5 Pressure tests of enclosures ............................................................................................................... 54 7.6 Mechanical operation tests ................................................................................................................ 55 7.7 Tests on auxiliary circuits, equipment, and interlocks in the control mechanism.............................. 55 7.8 Pressure test on partitions .................................................................................................................. 55 8. Gas handling ............................................................................................................................................. 55 9. Field testing .............................................................................................................................................. 55 9.1 Mechanical tests: leakage .................................................................................................................. 56 9.2 Mechanical tests: gas quality (moisture, purity, and density) ............................................................ 56 9.3 Electrical tests: continuity, conductivity, and resistivity ................................................................... 56 9.4 Electrical tests: low frequency ac voltage withstand ......................................................................... 56 9.5 Electrical tests: low frequency ac voltage withstand requirements and conditions ........................... 57 9.6 Electrical tests: low frequency ac voltage withstand configurations and applications ...................... 57 9.7 Electrical tests: dc voltage withstand tests ......................................................................................... 58 9.8 Electrical tests: assessment of the ac voltage withstand test .............................................................. 58 9.9 Electrical tests: tests on auxiliary circuits .......................................................................................... 58 9.10 Mechanical and electrical functional tests: checks and verifications ............................................... 58 9.11 Mechanical and electrical tests: documentation............................................................................... 59

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Annex A (normative) Switch testing procedures.......................................................................................... 60 A.1 Bus-transfer making and breaking tests ............................................................................................ 60 A.2 Switching of bus charging currents by disconnect switches 72.5 kV and above ............................. 62 A.3 Induced current switching of grounding switches ............................................................................ 66 A.4 Tests on the power kinematic chain .................................................................................................. 71 A.5 Test on the position-indicating kinematic chain ............................................................................... 73

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IEEE Standard for High Voltage Gas-Insulated Substations Rated Above 52 kV IMPORTANT NOTICE: This standard is not intended to ensure safety, security, health, or environmental protection. Implementers of the standard are responsible for determining appropriate safety, security, environmental, and health practices or regulatory requirements. This IEEE document is made available for use subject important notices and legal disclaimers. These notices and disclaimers appear in all publications containing this document and may be found under the heading “Important Notice” or “Important Notices and Disclaimers Concerning IEEE Documents.” They can also be obtained on request from IEEE or viewed at http://standards.ieee.org/IPR/disclaimers.html.

1. Overview 1.1 Scope This standard establishes ratings and requirements for planning, design, testing, installation, and operation of gas-insulated substations for alternating-current applications above 52 kV. Typical installations are assemblies of specialized devices such as circuit breakers, switches, bushings, buses, instrument transformers, cable terminations, instrumentation and controls, and the gas-insulating system. It does not include certain items that may be directly connected to gas-insulated substations, such as power transformers and protective relaying. This standard does not apply to gas-insulated transmission lines.

1.2 Normative references The following referenced documents are indispensable for the application of this document (i.e., they must be understood and used, so each referenced document is cited in text and its relationship to this document is explained). For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments or corrigenda) applies. ANSI/ASME Boiler and Pressure Vessel Code, Section VIII: Pressure Vessels, Division 1. 1 2

1 ANSI Standards are available from the American National Standards Institute, 11 West 42nd Street, 13th Floor, New York, NY 10036, USA. 2 The IEEE standards or products referred to in Clause 2 are trademarks owned by the Institute of Electrical and Electronics Engineers, Incorporated.

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IEEE Std C37.122-2010 IEEE Standard for High Voltage Gas-Insulated Substations Rated Above 52 kV

ANSI/ASME B31.1, Power Piping. ANSI/NEMA CC 1, Electric Power Connection for Substations. CENELEC EN 50052, Specification for Cast Aluminum Alloy Enclosures for Gas-Filled High-Voltage Switchgear and Controlgear. 3 CENELEC EN 50064, Specification for Wrought Aluminum and Aluminum-Alloy Enclosures for GasFilled High-Voltage Switchgear and Controlgear. CENELEC EN 50069, Specification for Welded Composite Enclosures of Cast and Wrought Aluminum Alloys for Gas-Filled High-Voltage Switchgear and Controlgear. IEC 60044-1, Instrument transformers—Part 1: Current transformers. 4 IEC 60044-2, Instrument transformers—Part 2: Inductive voltage transformers. IEC 61180-1, High-voltage test techniques for low-voltage equipment—Part 1: Definitions, test and procedure requirements. IEC 61462, Composite hollow insulators—Pressurized and unpressurized insulators for use in electrical equipment with rated voltage greater than 1000 V—Definitions, test methods, acceptance criteria and design recommendations. IEC 61639, Direct connection between power transformers and gas-insulated metal-enclosed switchgear for rated voltages of 72,5 kV and above. IEC 62155, Hollow pressurized and unpressurized ceramic and glass insulators for use in electrical equipment with rated voltages greater than 1000 V. IEC 62262, Degrees of protection provided by enclosures for electrical equipment against external mechanical impacts (IK code). IEC 62271-1, High-voltage switchgear and controlgear—Part 1: Common specifications. IEC 62271-102, High-voltage switchgear and controlgear—Part 102: Alternating current disconnectors and earthing switches. IEC 62271-203, High-voltage switchgear and controlgear—Part 203: Gas-insulated metal-enclosed switchgear for rated voltages above 52 kV. IEC 62271-209, High-voltage switchgear and controlgear—Part 209: Cable connections for gas-insulated metal-enclosed switchgear for rated voltages above 52 kV. Fluid-filled and extruded insulation cables. Fluid-filled and dry-type cable-terminations. IEC 62271-303, High-voltage switchgear and controlgear—Part 303: Use and handling of sulfur hexafluoride (SF6).

3 CENELEC publications are available from the Sales Department, American National Standards Institute, 11 West 42nd Street, 13th Floor, New York, NY 10036, USA. 4 IEC publications are available from IEC Sales Department, Case Postale 131, 3 rue de Varembe., CH-1211, Geneva 20, Switzerland/Suisse. IEC publications are also available in the United States from the Sales Department, American National Standards Institute, 11 West 42nd Street, 13th Floor, New York, NY 10036, USA.

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IEEE Std C37.122-2010 IEEE Standard for High Voltage Gas-Insulated Substations Rated Above 52 kV

IEEE Std C37.04TM, IEEE Standard Rating Structure for AC High-Voltage Circuit Breakers Rated on a Symmetrical Current Basis. 5 IEEE Std C37.06TM, IEEE Standard for AC High-Voltage Circuit Breakers Rated on a Symmetrical Current Basis—Preferred Ratings and Related Required Capabilities for Voltages Above 1000 V. IEEE Std C37.09TM, IEEE Standard Test Procedure for AC High-Voltage Circuit Breakers Rated on a Symmetrical Current Basis. IEEE Std C37.010TM, IEEE Application Guide for AC High-Voltage Circuit Breakers Rated on a Symmetrical Current Basis. IEEE Std C37.011TM, IEEE Application Guide for Transient Recovery Voltage for AC High-Voltage Circuit Breakers Rated on a Symmetrical Current Basis. IEEE Std C37.012TM, IEEE Application Guide for Capacitance Current Switching for AC High-Voltage Circuit Breakers Rated on a Symmetrical Current Basis. IEEE Std C37.015TM, IEEE Guide for the Application for Shunt Reactor Switching. IEEE P1712TM, Draft 7, August 2007, Draft Guide for Sulfur Hexafluoride (SF6) Gas Handling for High Voltage (over 1000 Vac) Equipment. 6 IEEE PC37.017TM, Draft 4, February 2010, Draft Standard for Bushings for High Voltage (over 1000 Volts ac) Circuit Breakers and Gas-Insulated Switchgear. 7 IEEE Std C37.21TM, IEEE Standard for Control Switchboards. IEEE Std C37.24TM, IEEE Guide for Evaluating the Effect of Solar Radiation on Outdoor Metal-Enclosed Switchgear. IEEE Std C37.100TM, IEEE Standard Definitions for Power Switchgear. IEEE Std C37.100.1TM-2007, IEEE Standard of Common Requirements for High Voltage Power Switchgear Rated Above 1000 V. IEEE Std C37.301TM, IEEE Standard for High-Voltage Switchgear (Above 1000 V) Test Techniques— Partial Discharge Measurements. IEEE Std C57.13TM, IEEE Standard Requirements for Instrument Transformers. IEEE Std 48TM, IEEE Standard Test Procedures and Requirements for Alternating-Current Cable Terminations 2.5 kV through 765 kV. IEEE Std 80TM, IEEE Guide for Safety in AC Substation Grounding. IEEE Std 315TM, IEEE Standard/American National Standard/Canadian Standard: Graphic Symbols for Electrical and Electronics Diagrams (Including Reference Designation Letters).

5 IEEE publications are available from the Institute of Electrical and Electronics Engineers, 445 Hoes Lane, P.O. Box 1331, Piscataway, NJ 08855-1331, USA. 6 Numbers preceded by P are IEEE authorized standards projects that were not approved by the IEEE-SA Standards Board at the time this publication went to press. For information about obtaining drafts, contact the IEEE-SA. 7 IEEE PC37.017, Draft 6, was approved as a standard by the IEEE Standards Board on 8 December, 2010 (IEEE Std C37.0172010).

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IEEE Std C37.122-2010 IEEE Standard for High Voltage Gas-Insulated Substations Rated Above 52 kV

IEEE Std 367TM, IEEE Recommended Practice for Determining the Electric Power Station Ground Potential Rise and Induced Voltage From a Power Fault. IEEE Std 693TM, IEEE Recommended Practices for Seismic Design of Substations. IEEE Std 1300TM, IEEE Guide for Cable Connections for Gas-Insulated Substations. IEEE Std 1416TM, IEEE Recommended Practice for the Interface of New Gas-Insulated Equipment in Existing Gas-Insulated Substations.

2. Normal (usual) and special (unusual) service conditions 2.1 Normal (usual) service conditions Subclause 2.1 of IEEE Std C37.100.1-2007 applies with the following additions: Vibration and shock. The equipment shall withstand for its service life the vibration of any directly connected equipment, such as transformers, and the shock caused by the operation or maintenance of the equipment. 2.1.1 Indoor switchgear Subclause 2.1.1 of IEEE Std C37.100.1-2007 applies. Many indoor applications do not require –30 °C low temperature capability. In these cases –25 or –5 °C are common values specified. 2.1.2 Outdoor switchgear Subclause 2.1.2 of IEEE Std C37.100.1-2007 applies with following additions and modifications: Wind speed value of 40 m/s stated in 2.1.2 f) of IEEE Std C37.100.1-2007 is applied in some specific regions as in North America. Lower wind speed value of 34 m/s may be applied in some specific regions, as stated in corresponding clause of IEC 62271-1. For installations in a location where the ice loading can be outside the normal (usual) service condition as stated in 2.1.2 of IEEE Std C37.100.1-2007, the preferred maximum ice loading values are: a) b)

10 mm for class 10 20 mm for class 20

2.2 Special (unusual) service conditions for both indoor and outdoor switchgear 2.2.1 Altitude Subclause 2.2.1 of IEEE Std C37.100.1-2007 applies. 2.2.2 Exposure to excessive pollution Subclause 2.2.2 of IEEE Std C37.100.1-2007 applies. 2.2.3 Temperature and humidity Subclause 2.2.3 of IEEE Std C37.100.1-2007 applies.

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IEEE Std C37.122-2010 IEEE Standard for High Voltage Gas-Insulated Substations Rated Above 52 kV

2.2.4 Exposure to abnormal vibration, shock, or tilting Subclause 2.2.4 of IEEE Std C37.100.1-2007 applies. 2.2.5 Other special (unusual) service conditions 2.2.5.1 Exposure to damaging fumes, vapor, steam, oil vapors, salt air, and hot and humid climate Subclause 2.2.5.1 of IEEE Std C37.100.1-2007 applies. 2.2.5.2 Exposure to excessive dust or abrasive, magnetic, or metallic dust Subclause 2.2.5.2 of IEEE Std C37.100.1-2007 applies. 2.2.5.3 Exposure to explosive mixtures of dust or gases Subclause 2.2.5.3 of IEEE Std C37.100.1-2007 applies. 2.2.5.4 Unusual space limitations Subclause 2.2.5.4 of IEEE Std C37.100.1-2007 applies.

3. Definitions For the purposes of this standard, the following terms and definitions apply. IEEE Std C37.100 should be referenced for terms not defined in this clause. For terms that are not listed in IEEE Std C37.100 users should refer to The IEEE Standards Dictionary: Glossary of Terms & Definitions. 8 alarm pressure pae (or density ae): For insulation and/or switching pressure (Pa), referred to the standard atmospheric air conditions of +20 °C and 101.3 kPa (or density), which may be expressed in relative or absolute terms, at which a monitoring signal may be provided. bus-charging current (rated): Current expressed as steady-state rms value which a disconnect switch is capable of switching when energizing or de-energizing parts of a bus system or similar capacitive loads. bus-transfer current: The current that flows in a disconnect switch when it transfers load from one bus system to another. bus-transfer voltage: The power-frequency voltage across the open disconnect switch gap after breaking or before making the bus-transfer current. class A grounding switch: A grounding switch designated to be used in circuits having relatively short sections of line or low coupling to adjacent energized circuits. class B grounding switch: A grounding switch designated to be used in circuits having relatively long lines or high coupling to adjacent energized circuits. compartment (GIS): A section of a gas-insulated switchgear assembly that is enclosed except for openings necessary for interconnection providing insulating gas isolation from other compartments. A compartment may be designated by the main components in it, e.g., circuit breaker compartment, disconnect switch compartment, bus compartment, etc. 8

The IEEE Standards Dictionary: Glossary of Terms & Definitions is available at http://shop.ieee.org/.

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IEEE Std C37.122-2010 IEEE Standard for High Voltage Gas-Insulated Substations Rated Above 52 kV

design pressure of enclosures: The maximum gas pressure to which a gas-insulated switchgear enclosure will be subjected under normal service conditions, including the heating effects of rated continuous current. electromagnetically induced current (grounding switch): The inductive current that a grounding switch is capable of switching when it connects to and disconnects from ground one termination of a deenergized transmission line, with the other termination grounded, and with an energized line carrying current in parallel with, and in proximity to, the grounded line. electrostatically induced current (grounding switch): The capacitive current that a grounding switch is capable of switching when it connects to or disconnects from ground one termination of a de-energized transmission line, with the other termination open, and with an energized line in parallel with, and in proximity to, the grounded line. gas monitoring systems: Any instrumentation for measuring, indicating, or giving remote warning of the condition or change in condition of the gas in the enclosure, such as pressure, density, moisture content, etc. gas-insulated switchgear (GIS): A compact, multi-component assembly, enclosed in a grounded metallic housing in which the primary insulating medium is SF6 and which normally includes buses, switches, circuit breakers, and other associated equipment. gas-insulated switchgear enclosure: A grounded part of gas-insulated metal-enclosed switchgear assembly retaining the insulating gas under the prescribed conditions necessary to maintain the required insulation level, protecting the equipment against external influences and providing a high degree of protection from approach to live energized parts. gas-insulated switchgear enclosure currents: Currents that result from the voltages induced in the metallic enclosure by effects of currents flowing in the enclosed conductors. gas leakage rate (absolute): Amount of gas escaped by time unit expressed in units Pa × m3/s. gas leakage rate (relative): Absolute leakage rate related to the total amount (mass or volume) of gas in each compartment at rated filling pressure (or density). It is expressed in percentage per year. gas pass through insulator: An internal insulator supporting one or more conductors specifically designed to allow the passage of gas between adjoining compartments. gas zone: A section of the GIS which may consist of one or several gas compartments which have a common gas monitoring system. The enclosure can be single-phase or three-phase. local control cubicle (or cabinet) (LCC): Cubicle or cabinet typically containing secondary equipment including control and interlocking, measuring, indicating, alarm, annunciation, and mimic one-line diagram associated with the primary equipment. It may also include protective relays if specified by the user. minimum functional pressure pme (or density me): Insulation and/or switching pressure (in Pa), at and above which rated characteristics of switchgear are maintained. It is referred to at the standard atmospheric air conditions of +20 °C and 101.3 kPa (or density) and may be expressed in relative or absolute terms. partition: Part of an assembly separating one compartment from other compartments. It provides gas isolation and support for the conductor (gas barrier insulator).

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IEEE Std C37.122-2010 IEEE Standard for High Voltage Gas-Insulated Substations Rated Above 52 kV

power kinematic chain: Mechanical connecting system from and including the operating mechanism up to and including the moving contacts. NOTE—(Figure A.8). 9

rated filling pressure pre: Insulation and/or switching pressure (in Pa), to which the assembly is filled before putting into service. It is referred to at the standard atmospheric air conditions of +20 °C and 101.3 kPa (or density) and may be expressed in relative or absolute terms. rated pressure of compressed gas supply controlled pressure systems: Rated pressure of a volume which is automatically replenished from an external compressed gas supply or internal gas source. rated supply frequency of closing and opening devices and of auxiliary circuits: The frequency of the rated supply voltage, either dc, 50 Hz or 60 Hz ac. rated supply voltage of closing and opening devices and of auxiliary circuits (Ua): The supply voltage of closing and opening devices and auxiliary and control circuits shall be understood to mean the voltage measured at the circuit terminals of the apparatus itself during its operation, including, if necessary, the auxiliary resistors or accessories supplied or required by the manufacturer to be installed in series with it, but not including the conductors for the connection to the electricity supply. transient voltage to ground (TVE): Voltage from conductor to enclosure which appears at the first prestrike during a closing operation. very fast transient (VFT): A class of transients generated internally within GIS characterized by short duration and very high frequency. water vapor (moisture) content: The amount of water in parts per million by volume (ppmv) that is in the gaseous state and mixed with the insulating gas at 20 °C and rated filling pressure. NOTE—The terms pressure and density are often used interchangeably, but are not interchangeable. In general, pressure is used in relation to the mechanical properties of the enclosure and density in relation to electrical characteristics and performance. Often when the term pressure is used (fill pressure for example) it is referenced to a specific temperature and is therefore actually specifies a gas density.

4. Ratings The following are electrical ratings that all components within a GIS shall meet or exceed: a) b) c) d) e) f) g) h) i)

Rated maximum voltage (V) or (Ur) Rated insulation level (Ud), (Us), (Up) Rated power frequency (fr) Rated continuous current (Ir) Rated short-time withstand current (Ik) Rated peak withstand current (Ip) Rated duration of short-circuit (tk) Rated supply voltage of closing and opening devices and of auxiliary circuits (Ua) Rated supply frequency of closing and opening devices and of auxiliary circuits

For list and definition of symbols, refer to Table H.1 of IEEE Std C37.100.1-2007. 9 Notes in text, tables, and figures of a standard are given for information only and do not contain requirements needed to implement this standard.

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IEEE Std C37.122-2010 IEEE Standard for High Voltage Gas-Insulated Substations Rated Above 52 kV

4.1 Rated maximum voltage (V) or (Ur) Subclause 4.1 of IEEE Std C37.100.1-2007 applies with the following addition: Components forming part of the GIS may have individual values of rated voltage in accordance with the relevant standards (e.g., voltage transformers).

4.2 Rated insulation level (Ud, Us, Up) Table 1 gives the preferred values for GIS. In the event of a conflict in circuit breaker dielectric test levels between this document and IEEE Std C37.06, this document shall take precedence. For GIS application, the dielectric characteristics of the internal insulation are identical whatever the altitude with those measured at sea level. Specific requirements concerning altitude are not applicable except for external insulation (air to gas bushings).

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IEEE Std C37.122-2010 IEEE Standard for High Voltage Gas-Insulated Substations Rated Above 52 kV

Table 1 —Preferred rated insulation values

Rated max. voltage V (Ur) (kV rms)

a

Rated powerfrequency withstand voltage

Rated switching impulse withstand voltage

Rated lightning impulse withstand voltage

(kV peak)

(kV peak)

(kV rms) Test levels Ud

Disconnect switch open gap

72.5

140

100

Test levels (phase to ground) Us

Test levels Up

Disconnect switch open gap

160

325

375

185

210

450

520

123

230

265

550

630

145

275

315

650

750

170

325

375

750

860

245a

425

490

900

1035

245

460

530

1050

1200

300

460

595

850

1275

700(+245)

1050

1050(+170)

362

a

500

650

850

1275

700(+295)

1050

1050(+205)

362

520

675

950

1425

800(+295)

1175

1175(+205)

420

650

815

1050

1575

900(+345)

1425

1425(+240)

550

740

925

1175

1760

900(+450)

1550

1550(+315)

800

960

1270

1425

2420

1100(+650)

2100

2100(+455)

Test levels Disconnect (phase to switch open gap phase) (+ bias)

Disconnect switch open gap (+ bias)

These rows represent additional ratings not harmonized with other international standards.

NOTE—The rated values of this table differ from previous IEEE Std C37.122 and IEEE Std C37.06 values in the interest of harmonization with IEC values and increasing withstand margins across open disconnect switch gaps. AC open gap withstands have been increased from approximately 110% of line to ground withstand for all ratings, to approximately 115% for 245 kV and below and approximately 130% for ratings above 245 kV. This does not imply that equipment in presently in service needs to be replaced as older levels have proven adequate.

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IEEE Std C37.122-2010 IEEE Standard for High Voltage Gas-Insulated Substations Rated Above 52 kV

4.2.1 Rated switching impulse withstand voltage Bias values in parenthesis in Table 1 are the peak values of the power-frequency voltage of opposite polarity of the applied impulse applied to the opposite terminal (combined voltage) which is V × ¥2/¥3. 4.2.2 Rated lightning impulse withstand voltage Bias values in parenthesis in Table 1 are the 70% of the peak values of the power-frequency voltage of opposite polarity of the applied impulse applied to the opposite terminal (combined voltage) which is 0.7 × V × ¥2/¥3. 4.2.3 Chopped wave test The chopped wave test requirements specified in IEEE Std C37.100.1-2007 do not apply to GIS equipment.

4.3 Rated power frequency (fr) Subclause 4.3 of IEEE Std C37.100.1-2007 applies with the following addition: Special application power frequencies include 16 2/3 Hz and 25 Hz.

4.4 Rated continuous (normal) current and temperature rise 4.4.1 Rated continuous (normal) current (Ir) Subclause 4.4.1 of IEEE Std C37.100.1-2007 applies with the following addition: Some main circuits of GIS (e.g., buses, feeder circuits, etc.) may have different values of rated continuous current. These values shall also be selected as per 4.4.1 of IEEE Std C37.100.1-2007. 4.4.2 Temperature rise Subclause 4.4.2 of IEEE Std C37.100.1-2007 applies with the following exceptions to IEEE Std C37.100.1-2007, Table 3, Item 9: Solar effects are included in outdoor applications. Allowable maximum temperatures and allowable temperature rises are shown in Table 2.

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IEEE Std C37.122-2010 IEEE Standard for High Voltage Gas-Insulated Substations Rated Above 52 kV

Table 2 —Allowable maximum temperature and allowable temperature rise Maximum temperature (°C)

Maximum temperature rise at ambient air temperature not exceeding 40 °C (°C)

Points contacted during routine operation and inspection specifically the local control cabinet

50

na

Which are expected to be contacted in normal operation and routine maintenance

70

30

Which need not to be contacted in normal operation

80

40

Nature of the part

Accessible parts: ⎯

⎯

⎯

NOTE—These temperatures are rarely reached in typical applications except under peak load/outage conditions.

4.5 Rated short-time withstand current (Ik) Subclause 4.5 of IEEE Std C37.100.1-2007 applies.

4.6 Rated peak withstand current (Ip) Subclause 4.6 of IEEE Std C37.100.1-2007 applies.

4.7 Rated duration of short-circuit (tk) Subclause 4.7 of IEEE Std C37.100.1-2007 applies with the standard duration for the short-time current as 1 second.

4.8 Rated supply voltage of closing and opening devices and of auxiliary and control circuits (Ua) Subclause 4.8 of IEEE Std C37.100.1-2007 applies.

4.9 Rated supply frequency of closing and opening devices and of auxiliary and control circuits Subclause 4.9 of IEEE Std C37.100.1-2007 applies.

4.10 Rated bus-transfer voltage and current 10 Rated bus-transfer voltages are given in Table 3. Other rated bus-transfer voltages may be assigned by the manufacturer. 10

Extracts used from Annex B of IEC 62271-102 with permission. Copyright © 2001 IEC Geneva, Switzerland. www.iec.ch.

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IEEE Std C37.122-2010 IEEE Standard for High Voltage Gas-Insulated Substations Rated Above 52 kV

The value of the rated bus-transfer current for disconnect switches shall be 80% of the rated continuous current. It will normally not exceed 1600 A, irrespective of the rated continuous current of the disconnect switch. NOTE—A maximum rated bus-transfer current of 1600 A was chosen as being typically the highest current which can be switched even though the rated normal current of the disconnect switch may be substantially greater. It is required to select disconnect switches based on the short-time current ratings as well as the rated normal current. The maximum continuous current carried by the disconnect switch, therefore, may be considerably less than the rated normal current. Rated bus-transfer currents greater than 80% of the rated normal current or greater than 1600 A may be assigned by the manufacturer.

Table 3 —Bus-transfer voltage Rated voltage Ur

Gas-insulated disconnect switches

kV

V rms

72.5 100 123

10

145 170 245 300 20 362 420 550 40 800

4.11 Rated induced current and voltage for grounding switches 11 Separate ratings for electromagnetically induced and electrostatically induced currents shall be assigned. The rated induced current is the maximum current that the grounding switch is capable of switching at the rated induced voltage. The rated induced voltage is the maximum power-frequency voltage at which the grounding switch is capable of switching the rated induced current. Rated induced currents for the two classes (A and B) of grounding switches are given in Table 4. The grounding switch shall be capable of carrying the rated induced current indefinitely. Separate ratings for electromagnetically and electrostatically induced voltages shall be assigned. Rated induced voltages for the two classes (A and B) of grounding switches are given in Table 4.

11

Extracts used from Annex C of IEC 62271-102 with permission. Copyright © 2001 IEC Geneva, Switzerland. www.iec.ch.

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IEEE Std C37.122-2010 IEEE Standard for High Voltage Gas-Insulated Substations Rated Above 52 kV

Table 4 —Standardized values of rated induced currents and voltages for grounding switches Electromagnetic coupling Rated voltage Ur kV

Rated induced current A (rms)

Electrostatic coupling

Rated induced voltage kV (rms)

Rated induced current A (rms)

Class

Rated induced voltage kV (rms)

Class

A

B

A

B

A

B

A

B

72.5

50

80

0.5

2

0.4

2

3

6

100

50

80

0.5

2

0.4

2

3

6

123

50

80

0.5

2

0.4

2

3

6

145

50

80

1

2

0.4

2

3

6

170

50

80

1

2

0.4

3

3

9

245

80

80

1.4

2

1.25

3

5

12

300

80

160

1.4

10

1.25

10

5

15

362

80

160

2

10

1.25

18

5

17

420

80

160

2

10

1.25

18

5

20

550

80

160

2

20

2

25

8

25

800

80

160

2

20

3

25

12

32

NOTE 1—Class A grounding switches: low coupling or relatively short parallel lines. Class B grounding switches: high coupling or relatively long parallel lines. See definitions Clause 3. NOTE 2—In some situations (very long sections of the grounded line in proximity to an energized line; very high loading on the energized line; energized line having a service voltage higher than the grounded line, etc.), the induced current and voltage may be higher than the given values. For these situations, the rated values should be subject to agreement between manufacturer and user. The rated induced voltages correspond to line-to-ground values for both single-phase and three-phase tests (see A.3.6).

4.12 Rated short-circuit making current for grounding switches A grounding switch which has a rated short-circuit making current assigned shall be capable of making at any applied voltage or current, up to and including the rated maximum voltage and any current up to and including the rated short-circuit making current. For a grounding switch with a rated short-circuit making current, this rating shall be equal in magnitude to the rated peak withstand current.

5. Design and construction High-voltage, gas-insulated switchgear primarily consists of grounded pressurized metal enclosures, containing energized high-voltage conductors, and other switchgear components. It is located in areas accessible to authorized personnel only, and operated by trained (qualified) personnel. Under certain conditions both conductors and enclosures shall be capable of carrying rated continuous current and shortcircuit currents. GIS enclosures shall be filled with compressed sulfur-hexafluoride (SF6) insulating gas. Gas-insulated switchgear shall be designed for safe operation in normal service, during inspection and maintenance operations, and during testing on connected cables or other apparatus. It shall also be

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IEEE Std C37.122-2010 IEEE Standard for High Voltage Gas-Insulated Substations Rated Above 52 kV

designed such that normal grounding switch operations can be carried out safely. Components of the same rating and construction which may require replacement shall be interchangeable. Components contained within the GIS enclosure are subject to their relevant standards except this standard shall take precedence where it modifies those standards.

5.1 Requirements for liquid in switchgear Subclause 5.1 of IEEE Std C37.100.1-2007 applies.

5.2 Requirements for gases in switchgear Subclause 5.2 of IEEE Std C37.100.1-2007 applies with the following addition: For compliance with local regulations, refer to 5.20.4 of this standard.

5.3 Grounding and bonding of switchgear Subclause 5.3 of IEEE Std C37.100.1-2007 applies with the following additions: 5.3.1 Grounding of enclosures The metallic enclosure shall be equipped with ground pads providing for connections to the ground grid, sized for the short-circuit current at each location which corresponds to the current specified for the installation. The ground pad shall conform to a hole pattern in accordance with ANSI/NEMA CC 1. All metal parts that do not belong to a main or auxiliary circuit shall be grounded. For the interconnection of enclosures, frames, etc., bolting or welding is acceptable to provide electrical continuity. Connections shall meet the requirements of IEEE Std 80 and IEEE Std 367. The continuity of the grounding circuits shall be assured, taking into account the thermal and electrical stresses caused by the current they may carry. The grounding system shall prevent step and touch voltages exceeding the limits defined in IEEE Std 80. 5.3.2 Grounding of high-voltage circuit All high-voltage parts where access is required or provided shall be capable of being grounded during maintenance. 5.3.3 Bonding of enclosures The various sections of the enclosure shall be electrically connected (bonded) together to provide a continuous current path through the entire length. Single-phase enclosures require bonding interconnections installed between the three-phase enclosures to provide a path for longitudinal continuous currents induced in the enclosures. Each of these bonding interconnections shall be connected to the ground grid as directly as possible by conductors capable of carrying the rated short-circuit current and the portion of the continuous current that flows into the ground. The bonding interconnections between single-phase enclosures are intended to significantly reduce or eliminate the continuous currents induced in the enclosures from flowing into the ground grid. They are dimensioned for rated continuous current of the installation and are typically located at the extremities of the installation and at selected intermediate locations.

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IEEE Std C37.122-2010 IEEE Standard for High Voltage Gas-Insulated Substations Rated Above 52 kV

5.4 Auxiliary and control equipment Control and secondary circuit devices and wiring shall comply with the requirements of IEEE Std C37.21.

5.5 Dependent power operation Subclause 5.5 of IEEE Std C37.100.1-2007 applies.

5.6 Stored energy 12 A switching device arranged for stored energy operation shall be capable of making and breaking all currents up to its rated values when the energy storage device is suitably charged. Closing and opening times as stated by the manufacturer shall remain within manufacturer-stated limits at rated control voltage. Except for slow operation during maintenance, the main contacts shall only move under the action of the drive mechanism and in the designed manner. A device indicating when the energy storage device is charged shall be mounted on the switching device. It shall not be possible for the moving contacts to move from one position to the other, unless the stored energy is sufficient for satisfactory completion of the opening or closing operation. Stored energy devices shall be able to be discharged to a safe level prior to access. 5.6.1 Energy storage in springs (or weights) When the energy storage device is a spring (or weight), the requirements of 5.6 apply when the spring is charged (or the weight lifted). 5.6.2 Manual charging If a spring (or weight) is charged by hand, the direction of motion of the handle shall be marked. The manual charging facility shall be designed such that the handle is not driven by the operation of the switching device or by application of control supply voltage. The maximum actuating force required for manually charging a spring (or weight) shall not exceed 250 N (56 lb). 5.6.3 Energy storage in capacitors When the energy storage device is a charged capacitor, the requirements of 6.6 apply.

5.7 Independent manual operation Subclause 5.7 of IEEE Std C37.100.1-2007 applies.

5.8 Operation of releases The operation limits of releases for circuit breakers are given in IEEE Std C37.100.

12

Extracts used from 5.6 of IEC 62271-1 with permission. Copyright © 2007 IEC Geneva, Switzerland. www.iec.ch.

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IEEE Std C37.122-2010 IEEE Standard for High Voltage Gas-Insulated Substations Rated Above 52 kV

For other switches, shunt closing and opening releases shall operate satisfactorily with the rated supply voltage and rated supply frequency given in 4.8 and 4.9 of IEEE Std C37.100.

5.9 Low- and high-pressure interlocking and monitoring devices Subclause 5.9 of IEEE Std C37.100.1-2007 applies with the following additions: The gas density or temperature compensated gas pressure in each gas zone shall be separately and continuously monitored. The monitoring device shall be capable of operating a relay contact upon descending gas density at each of two different density or pressure levels (alarm pressure and minimum functional pressure). If the device has a visual indicator, it shall be readable by the operator. Gas density monitors shall be capable of being functionally checked with the GIS equipment in service. Checking of gas density monitors without properly isolating contact outputs may initiate alarms and/or protective relay operations. Interface contacts shall be provided for first stage and lockout gas densities for each gas zone for connection to user equipment. When the rated filling pressure differs between adjacent zones, an additional alarm indicating over pressure may be used. A means to sample gas in each gas compartment shall be provided.

5.10 Nameplates Subclause 5.10 of IEEE Std C37.100.1-2007 applies with the following additions: The nameplates shall be durable and clearly legible for the service life of the equipment. Symbols on GIS nameplates shall be in accordance with IEEE Std 315. 5.10.1 GIS common nameplates Nameplates of the following types shall be furnished in a convenient, central location to provide information for operation and maintenance. These nameplates shall be clearly readable and located in an appropriate and accessible location.

5.10.1.1 GIS ratings nameplate The ratings nameplate shall state to which of the GIS equipment the ratings apply. The GIS ratings nameplate shall contain the following information: a) b) c) d) e) f)

Manufacturer’s name, type and designation, and serial number Year of manufacture Rated maximum voltage (V) or (Ur) Rated lightning impulse withstand voltage (Up) Rated switching impulse withstand voltage (Us), (if applicable) Rated power-frequency withstand voltage (Ud)

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IEEE Std C37.122-2010 IEEE Standard for High Voltage Gas-Insulated Substations Rated Above 52 kV

g) h) i) j) k) l) m) n)

Rated power frequency (fr) Rated maximum and minimum ambient temperature Rated continuous current (Ir) at maximum ambient temperature Rated short-time withstand current (Ik) and duration Rated peak withstand current (Ip) Rated supply voltage of closing and opening devices and of auxiliary circuits (Ua) Rated supply frequency of closing and opening devices and of auxiliary circuits Contract order number

5.10.1.2 One-line diagram nameplate The one-line diagram nameplate shall show the following information if applicable: a) b) c) d) e) f) g) h) i)

Circuit breakers Disconnect switches Grounding switches Instrument transformers Bushings Power cable connections Buses Surge arresters User identification numbers

When the installation is an expansion of an existing substation, the one-line diagram shall show and identify the existing equipment and the new equipment as specified by the user. The one-line diagram nameplate may be combined with the insulating gas system nameplate (5.10.1.3) 5.10.1.3 Insulating gas system nameplate The insulating gas system nameplate shall contain the following information: a)

b) c) d) e) f)

Complete gas system schematic including compartmentalization, (including compartment designation), showing location and device number of: 1) Gas density monitors 2) Pressure gauges 3) Interconnections between gas compartments 4) Valves: fill, evacuation, sampling, isolation 5) Pressure relief location and operating pressure Weight of gas in each compartment and total weight of gas in the GIS at rated filling pressure (at 20 °C) Curves for gas showing maximum, rated filling, alarm and minimum functional pressures versus temperature Maximum allowable moisture level (ppmv) Insulating gas type Insulating gas pressure (at 20 °C), identified in either absolute or relative values: 1) Rated filling pressure 2) Alarm pressures 3) Minimum functional pressure 17 Copyright © 2011 IEEE. All rights reserved.

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IEEE Std C37.122-2010 IEEE Standard for High Voltage Gas-Insulated Substations Rated Above 52 kV

5.10.2 GIS equipment nameplates Main GIS equipment and operating devices shall be provided with nameplates which are located on the equipment themselves or in a conspicuous adjacent area. When common information of the GIS is stated on the ratings nameplate (5.10.1.1), individual equipment nameplates can be simplified. Equipment nameplates shall provide information according to its relevant standard. As a minimum, the information in the following sections is required: 5.10.2.1 Circuit breakers The nameplates for circuit breakers (and their operating mechanisms) shall contain the information described in IEEE Std C37.04. In addition it shall contain the following: a)

Insulating gas pressure (at 20 °C), identified in either absolute or relative values: 1) Rated filling pressure 2) Alarm pressures 3) Minimum functional pressure

5.10.2.2 Disconnect switches The nameplates for disconnect switches (and their operating mechanisms) shall contain the following information: a) b) c) d) e) f) g) h) i) j) k) l) m) n)

Manufacturer’s name, type and designation, and serial number Year of manufacture Rated maximum voltage (V or Ur ) Rated power-frequency withstand voltage (Ud) Rated lightning impulse withstand voltage (Up) Rated switching impulse withstand voltage (Us) (if applicable) Rated power frequency (fr) Rated continuous current (Ir) Rated short time withstand current (Ik) and duration Rated peak withstand current (Ip) Rated bus charging breaking current Rated bus-transfer current and voltage Rated filling pressure (pre) at 20 °C Rated auxiliary voltage (Ua)

5.10.2.3 Grounding switches The nameplates for grounding switches (and their operating mechanisms) shall contain the following information: a) b) c) d)

Manufacturer’s name, type and designation, and serial number Year of manufacture Rated maximum voltage (V or Ur ) Rated power-frequency withstand voltage (Ud)

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e) f) g) h) i) j) k) l) m) n) o) p)

Rated lightning impulse withstand voltage (Up) Rated switching impulse withstand voltage (Us) (if applicable) Rated power frequency (fr) Rated short-time withstand current (Ik) and duration Rated peak withstand current (Ip) Rated short-circuit making current (high-speed grounding switches) Rated number of closings before maintenance at rated short-circuit making current (high-speed grounding switches) Rated closing time (high-speed grounding switches) Rated filling pressure (pre) Rated auxiliary voltage (Ua) Electrostatically induced current interruption rating (Class A and B high-speed grounding switches) Electromagnetically induced current interruption rating (Class A and B high-speed grounding switches)

5.10.2.4 Operating mechanisms The nameplates for GIS equipment operating mechanisms may be combined with the equipment nameplates The operating mechanism nameplates shall contain the following information: a) b) c) d) e) f) g)

Manufacturer’s name, type and designation, and serial number Year of manufacture Control voltage range and current Compressor, hydraulic pump, spring charging motor or operating motor voltage range Compressor, hydraulic pump, spring charging motor or operating motor starting and running currents Low-pressure alarm switch closing and opening pressure (if applicable) Low-pressure lock-out switch opening and closing pressure (if applicable)

5.10.2.5 Surge arresters The nameplates for surge arresters shall contain the information described in applicable surge arrester standards. As a minimum, they shall contain the following information: a) b) c) d) e) f) g)

Manufacturer’s name, type and designation, and serial number Year of manufacture Maximum continuous operating voltage (MCOV) Duty cycle voltage rating Nominal discharge current Identification of assembled position (vertical or horizontal) Nominal gas pressure (at 20 °C)

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IEEE Std C37.122-2010 IEEE Standard for High Voltage Gas-Insulated Substations Rated Above 52 kV

5.10.2.6 Current transformers The nameplates for current transformers shall contain the information described in IEEE Std C57.13 and IEC 60044-1. As a minimum, they shall contain the following information: a) b) c) d) e) f) g) h) i) j) k) l) m)

Manufacturer’s name, type and designation , and serial number Year of manufacture Rated frequency Accuracy class and the ratio for which the accuracy is expressed Rated maximum voltage (if applicable) Rated lightning impulse withstand voltage (if applicable) Rated switching impulse withstand voltage (if applicable) Rated primary current Rated secondary current Rated continuous thermal current factor and the associated ambient temperature Rated thermal short-time current Nominal gas pressure (at 20 °C) A connection diagram showing: 1) Full winding development 2) Taps 3) Ratio in terms of primary and secondary currents 4) Polarity

5.10.2.7 Voltage transformers The nameplates for voltage transformers shall contain the information described in IEEE Std C57.13 and IEC 60044-2. As a minimum, they shall contain the following information a) b) c) d) e) f) g) h) i) j) k) l)

Manufacturer’s name, type and designation , and serial number Year of manufacture Rated power frequency Rated primary voltage Rated lightning impulse withstand voltage Rated switching impulse withstand voltage (if applicable) Rated power-frequency withstand voltage Ratio or ratios Thermal burden rating or ratings at ambient temperature or temperatures, in voltamperes (VA) Accuracy rating at thermal burden rating Nominal gas pressure (at 20 °C) A connection diagram

5.10.2.8 High-voltage cable terminations The nameplates for high-voltage cable terminations shall contain the information described in IEEE Std 48. As a minimum, they shall contain the following information: a) b)

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c) d) e) f) g) h) i) j) k) l) m)

Rated maximum voltage (Ur) Rated lightning impulse withstand voltage (Up) Rated switching impulse withstand voltage (if applicable) (Us) Rated power-frequency withstand voltage (Ud) Rated maximum and minimum ambient temperature Rated continuous current (Ir) at maximum ambient temperature Rated short-time withstand current (Ik) Rated duration of short-circuit (tk) Rated peak withstand current (Ip) Nominal gas pressure (at 20 °C) Maximum allowable force applied in any direction at the external terminal

5.10.2.9 Bushings The nameplates of gas to oil bushings and gas to air bushings shall contain the information described in IEEE PC37.017, Draft 4, February 2010. As a minimum they should contain the following information: a) b) c) d) e) f) g) h) i) j) k) l) m) n) o) p) q)

Manufacturer’s name, type and designation, serial number Year of manufacture Rated maximum voltage (Ur) Rated lightning impulse withstand voltage (Up) Rated switching impulse withstand voltage (if applicable) (Us) Rated power-frequency withstand voltage (Ud) Rated maximum and minimum ambient temperature Rated continuous current (Ir) at maximum ambient temperature Rated short-time withstand current (Ik) and duration Rated short-circuit current (rms) and duration (tk) Rated peak withstand current (Ip) Rated oil-side pressure (applicable to gas to oil bushings only) Nominal gas pressure (at 20 °C) Maximum allowable force applied in any direction at the external terminal Maximum angle of mounting if exceeding 30 degrees from vertical Weight Voltage tap, capacitance C1 and C2 (if applicable)

5.11 Interlocking devices Subclause 5.11 of IEEE Std C37.100.1-2007 applies with the following addition: Suitable means of interlocking between circuit breakers, disconnecting switches, and grounding switches shall be provided. The interlocking system shall prevent a disconnecting switch operation (close or open) under load, prevent grounding switches from being closed into an energized bus and prevent a disconnect switch from being closed into a grounded bus. Disconnects used for bus-transfer switching may require a means to over-ride interlocks.

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IEEE Std C37.122-2010 IEEE Standard for High Voltage Gas-Insulated Substations Rated Above 52 kV

5.12 Position indication Subclause 5.12 of IEEE Std C37.100.1-2007 applies with the following addition: Subclause 5.28.2 of IEEE Std C37.122 is also applicable.

5.13 Degree of protection of enclosures Subclause 5.13 of IEEE Std C37.100.1-2007 applies.

5.14 Creepage distance for outdoor insulators Subclause 5.14 of IEEE Std C37.100.1-2007 applies only to gas/air bushings.

5.15 Gas and vacuum tightness The leakage rate from any single gas compartment to the atmosphere shall not exceed 0.5% per year. Leakage across the gas barrier insulator shall not prevent vacuum processing on one side with the other side at rated filling pressure.

5.16 Liquid tightness (insulating medium) Subclause 5.16 of IEEE Std C37.100.1-2007 does not apply.

5.17 Flammability 13 The materials should be chosen and the parts designed in such a way that they retard the propagation of any flame resulting from accidental overheating in the switchgear and controlgear and reduce harmful effects on the local environment. In cases where product performance requires the use of flammable materials, product design should take flame retardation into account, if applicable.

5.18 Electromagnetic compatibility (EMC) Subclause 5.18 of IEEE Std C37.100.1-2007 applies.

5.19 X-ray emission Subclause 5.19 of IEEE Std C37.100.1-2007 applies.

5.20 Design of pressurized enclosures 5.20.1 Thermal cycling, vibration, shock, and seismic loading Enclosures shall be designed to withstand all mechanical stresses normally encountered, including thermal cycling, vibration, and shock associated with operation. They shall be designed for seismic loading, if specified.

13

Extracts used from 5.17 of IEC 62271-1 with permission. Copyright © 2007 IEC Geneva, Switzerland. www.iec.ch.

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IEEE Std C37.122-2010 IEEE Standard for High Voltage Gas-Insulated Substations Rated Above 52 kV

5.20.2 Design pressure When designing an enclosure, in addition to the maximum filling pressure and maximum design temperature, the following items shall also be considered: a) b) c) d)

The evacuation of the enclosure as part of the gas processing The full differential pressure across the enclosure wall or partition In the case of adjacent gas compartments having different operating pressures, the resulting pressure in the event of a leak between the gas compartments (abnormal) The possibility of an internal fault (abnormal)

Components having pressurized enclosures other than metal, such as gas-insulated to atmospheric air bushings, shall conform to the applicable clause of the latest revision of IEEE Std C37.017, IEC 62155 or IEC 61462. 5.20.3 Design temperatures The maximum design temperature, for purposes of calculating the design pressure of the enclosure, shall be the average temperature of the gas inside the enclosure at rated continuous current, rated maximum ambient temperature, including solar radiation effects at rated gas pressure. This design temperature can be established from existing temperature-rise test data. Solar radiation effect should be evaluated using IEEE Std C37.24. 5.20.4 Calculation methods Methods for calculating the thickness and construction of the enclosures shall be chosen from established standards for pressurized enclosures of gas-filled, high-voltage switchgear with inert, non-corrosive, lowpressurized gases. CENELEC EN 50052, CENELEC EN 50064, CENELEC EN 50069, or other equivalent national standards may be used. Conformance to local or state codes may also be required and shall be agreed to between the manufacturer and the user. This may include compliance with codes not intended for electrical enclosures such as ANSI/ASME Boiler and Pressure Vessel Code Section VIII, Division 1.2, and ANSI/ASME B31.1. 5.20.5 Pressure coordination The pressure inside a GIS enclosure may vary from the rated filling pressure level due to different service conditions. Figure 1 shows the various pressure levels and their relationship. The manufacturer is responsible for choosing the minimum functional pressure for insulation and operation. The rated filling pressures are related to the alarm pressures and the leakage rate. Routine test pressure and type test pressure are based on design pressure taking into account material and manufacturing process factors.

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IEEE Std C37.122-2010 IEEE Standard for High Voltage Gas-Insulated Substations Rated Above 52 kV

Higher pressure Burst and rupture pressure of enclosures Type test pressure of enclosures Routine test pressure of enclosures Pressure-relief device operating pressure Design pressure of enclosures

Margin for pressure rise due to temperature

Rated filling pressure Margin for pressure loss due to gas leakage Alarm pressure Margin for pressure loss to allow for action Minimum functional pressure Lower pressure

Figure 1 —Pressure coordination of enclosures and pressure-relief device

5.20.6 Effects of internal arcing on a GIS enclosure In order to provide a high degree of protection to personnel, the external consequences of an internal arc shall be limited (by a suitable protective system) to the appearance of a hole or a tear in the enclosure without any fragmentation. The duration of the arc is related to the performance of the protective system determined by the first stage (main protection) and second stage (back-up protection). Table 5 gives the performance criteria for the duration of the arc according to the performance of the protective system. Manufacturer and user may define a time during which an arc due to an internal fault up to a given value of short-circuit current will cause no external effects. The definition of this time shall be based on test results or as mutually agreed calculation procedure by manufacturer and user. The duration of current without burn-through for different values of the short-circuit current may be estimated from a calculation procedure as mutually agreed upon by manufacturer and user.

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IEEE Std C37.122-2010 IEEE Standard for High Voltage Gas-Insulated Substations Rated Above 52 kV

Table 5 —Enclosure performance criteria for internal arc Rated short-circuit current

Protection stage

Duration of current

Performance criteria

1

0.2 s

No external effect other than the operation of suitable pressure-relief device

2

” 0.5 s

No fragmentation (burnthrough is acceptable)

1

0.1 s

No external effect other than the operation of suitable pressure-relief device

2

” 0.3 s

No fragmentation (burnthrough is acceptable)

< 40 kA rms

• 40 kA rms

5.20.7 Stress under abnormal pressure Enclosures shall withstand any increase in pressure due to internal arcs which create an abnormal pressure. The abnormal pressure to be withstood is defined as the pressure caused by an internal arc of current magnitude equal to the rated short-circuit current for a minimum duration as specified in Table 5. Calculation of stress or type tests shall indicate that a rupture of the enclosure will not occur under abnormal pressure. The rupture pressure shall be equal to or greater than 3.5 times the design pressure for cast and cast-welded enclosures and 2.3 times the design pressure for welded enclosures. 5.20.8 Pressure-relief devices Pressure-relief devices to relieve abnormal pressure shall be set to operate at a pressure not exceeding the routine test pressure. When determining the operating pressure of the pressure-relief device, transient pressure occurring during normal operation of devices (e.g., circuit breaker) shall be considered. Pressurerelief devices shall direct the escaping gases away from the normal path of personnel and shall not exhaust into control cabinets.

5.21 Access for operations and maintenance Personnel shall be able to access all viewports, gas sample ports, and other indicators, such as density monitors. Personnel shall also be able to access locations from which operation, routine inspection, and maintenance is performed The design shall not require climbing on the apparatus to gain access under routine conditions. Moveable ladders or platforms on casters may be deployed in lieu of fixed platforms under mutual agreement between manufacturer and user.

5.22 Bus expansion joints Expansion and installation alignment shall be considered in the design of the bus conductor and the enclosure. Expansion joints shall be provided, as required. When bellows are provided in the enclosure for installation alignment, means shall be provided to prevent movement after alignment is complete. Bellows provided to permit movement caused by expansion and contraction of the bus or foundation settlement 25 Copyright © 2011 IEEE. All rights reserved.

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IEEE Std C37.122-2010 IEEE Standard for High Voltage Gas-Insulated Substations Rated Above 52 kV

shall have specially designed means to preserve the mechanical strength of the bus and the enclosure as well as contact alignment and penetration. Joints provided for direct connection to transformers shall be designed to inhibit transfer of vibration from the transformer to the bus and the bus enclosure. The design shall prevent damage and uncontrolled extension of the expansion joint during service, installation, and maintenance.

5.23 Insulators, partitions, gas pass through insulators, and operating rods Insulators used to support live parts and to actuate the moving contacts of circuit breakers and switches shall be designed to withstand the operating temperatures specified in 2.2 and 4.4 without loss of mechanical or dielectric integrity. Insulators used as partitions shall be designed to withstand the constraints during the maintenance activity. The design pressure of the gas barrier insulator shall be the pressure across the gas barrier insulator when one side is vacuum while the other side is the pressure at maximum ambient temperature with solar radiation effect (where applicable) and rated continuous current (where applicable). See Figure 2. Testing of insulators is given in 6.12 and 6.14.

Higher pressure Burst pressure of partitions Type test pressure of partitions Routine test pressure of partitions Design pressure of partitions Rated filling pressure Margin for pressure loss due to gas leakage

Alarm pressure

Minimum functional pressure

Margin for pressure loss to allow for action

Lower pressure Figure 2 —Pressure coordination of partitions

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IEEE Std C37.122-2010 IEEE Standard for High Voltage Gas-Insulated Substations Rated Above 52 kV

5.24 Partitioning 14 GIS shall be divided into compartments such that taking one compartment out of service for maintenance, repair, on-site testing, or extension of the GIS will have minimal impact on the service continuity of the other compartments. The end user shall specify specific service continuity requirements to the manufacturer. The development of the electrical single-line diagram is key to optimizing service continuity.

5.25 Interfaces 5.25.1 Power cable connections Refer to IEEE Std 1300 and IEC 62271-209 which cover the connection assembly of fluid-filled and extruded solid dielectric power cables to GIS. These standards cover single or three-phase arrangements. These standards establish the electrical and mechanical interchangeability of interface arrangements. They also determine the limits of supply between the GIS manufacturer and the power cable supplier. The parts of GIS which remain connected to the cable termination shall be capable of withstanding the cable test voltages specified in IEEE Std 48. Direct current testing is not recommended for gas-insulated systems. 5.25.2 Direct transformer connections Refer to IEC 61639 which covers the connection assembly between GIS equipment and power transformers with completely immersed bushings. IEC 61639 establishes the electrical and mechanical interchangeability of interface arrangement. It also determines the limits of supply between the GIS manufacturer and the power transformer supplier. 5.25.3 Bushings The ratings of a bushing shall meet or exceed the ratings of the associated GIS. Bushings shall meet the requirements of IEEE PC37.017, Draft 4, February 2010. 5.25.4 Future expansion facilities GIS can be rearranged or new equipment added to existing equipment. It is recommended for future expansion of GIS that the user clearly indicate all locations where the future equipment might be joined to the existing GIS. To provide for efficient planning, the manufacturer shall provide, for each identified location where future expansion is planned to occur, shop drawings showing all pertinent dimensions, tolerances, material and hardware used, gas seals, gas system, pressure, and any other information that will support fabrication and installation of future transition compartments. Refer to IEEE Std 1416 on recommended practices for the interface of new gas-insulated equipment in existing gas-insulated switchgear.

14

Extracts used from 5.104 of IEC 62271-203 with permission. Copyright © 2003 IEC Geneva, Switzerland. www.iec.ch.

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IEEE Std C37.122-2010 IEEE Standard for High Voltage Gas-Insulated Substations Rated Above 52 kV

5.26 Seismic requirements All GIS shall be capable of withstanding at least 0.2 times the equipment weight applied in one horizontal direction, combined with 0.16 times the weight applied in the vertical direction at the center of gravity of the equipment and supporting structure. The resultant load shall be combined with the maximum normal operating load to develop the greatest stress on the anchorage. For guidance in the application of GIS, where the seismic conditions exceed those described here, refer to IEEE Std 693.

5.27 High-voltage circuit breakers High-voltage circuit breakers used in GIS shall conform to IEEE Std C37.04, IEEE Std C37.06, and IEEE Std C37.09. Application shall be made in accordance with the provisions of IEEE Std C37.010, IEEE Std C37.011, IEEE Std C37.012, and IEEE Std C37.015 as applicable. In case of disagreement, this document takes precedence over the above standards.

5.28 Disconnect switches These switches are intended to electrically isolate equipment. They are not intended (except as noted in 4.10) to interrupt currents other than the charging current of the equipment being isolated. This disconnect switch gap, without the associated grounding switch being closed, is not intended as an electrical safety barrier. See Table 1. 5.28.1 Bus-transfer current switching capability (special duty) Bus-transfer switching capability (parallel or loop switching) requirements are defined in 6.17 5.28.2 Switch position—reliability and indication The open and closed position of switches shall be clearly indicated, both mechanically and electrically. 5.28.2.1 Electrical switch position indication device The electrical indication for the closed and open switch position shall only be given when the movable contacts of the switch are completely closed or completely open. Therefore the kinematic chain between the movable contacts and the position-indicating device shall be designed with sufficient mechanical strength in accordance with specified tests (see A.4 and A.5). The position-indicating kinematic chain shall be a continuous mechanical connection to make certain of a positively driven operation. The position-indicating device may be marked directly on a mechanical part of the power kinematic chain by suitable means. Any strain limiting device, if provided, shall not be part of the position-indicating kinematic chain. Where all poles of a switch are mechanically coupled so as to be operable as a single unit, it is permissible to use a common position-indicating device. A type test of the kinematic chain is required. 5.28.2.2 Visible switch position observation The full open and full close switch position may be observed by video camera systems or viewports. In order to avoid eye damage from exposure to an arc, viewports should only be used to observe the contacts when no operation of the disconnect switch is expected.

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IEEE Std C37.122-2010 IEEE Standard for High Voltage Gas-Insulated Substations Rated Above 52 kV

NOTE—If the user selects viewports as the means of switch contact position observation, a weatherproof sign should be installed near each viewport to warn of possible danger when viewing the interior during switch operation. The suggested wording is as follows:

WARNING Do not look into the viewport during switch operation. Arcing may damage your eyes. . 5.28.3 Operating mechanisms Disconnecting switches may be either manually or electrically operated, with either single-pole or group operation. Power operators shall be equipped with provisions for manual operation and so arranged that electrical operation is prevented while the manual operating means is engaged. The disconnect switch contacts shall only move under the action of the drive mechanism and in the designed manner. The closed or open position of the disconnect switch contacts shall not change as a result of loss of the energy supply, or the re-application of the energy supply after a loss of energy, to the closing and/or opening device. Facilities for temporary locking the mechanism in closed or open position shall be available.

5.29 Grounding switches The main function of grounding switches is the grounding of specific sections of gas-insulated switchgear for safety of personnel during maintenance, extension, or repair work. 5.29.1 Maintenance grounding switches These switches are capable of carrying their rated peak withstand and short-time currents without sustaining damage and with no deterioration of their dielectric capabilities. These switches do not have an assigned making capability and are not capable of closing into an energized bus without sustaining damage. 5.29.2 High-speed grounding switches High-speed grounding switches, which are intended for fast closing operation only, can also have the denomination “fault-closing maintenance grounding switch.” These switches, in addition to being capable of carrying their rated peak withstand and short-time currents without sustaining damage and with no deterioration of their dielectric capabilities are equipped with power-operating mechanisms to provide fault-closing capabilities up to their rated short-circuit making current capacity. Following a fault-closing operation (which should be a rare occurrence caused only by inadvertent operation, malfunction, incorrect system operating procedure, etc.), the switch shall be capable of being opened and the associated circuit shall be capable of being placed back into service without maintenance. A maintenance inspection of the switch should be scheduled as early as is convenient following such a fault-closing operation. The ability of the associated circuit to be returned to service following the first fault-closing necessitates the design test requirements specified in 6.16. For manual operation of a high-speed ground switch, a suitable stored-energy device shall be installed to provide correct closing action independent of operator effort.

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IEEE Std C37.122-2010 IEEE Standard for High Voltage Gas-Insulated Substations Rated Above 52 kV

5.29.3 Insulated grounding switches Insulated grounding switches are similar to those described in 5.29.1 and 5.29.2, except with external, removable ground connections and suitable insulation between the grounded enclosure and the switch. They are used as maintenance grounding switches. In addition, with the ground connection removed, they can be used as test terminals for timing or resistance measurement of main contact parts, CT primary current injection, and for capacitance measurements. For group-operated switches, the inter-phase rods shall be equipped with insulated sections to provide for complete electrical isolation or shall have provisions to facilitate removal of the inter-phase rods when using the grounding switch as a test terminal. The power-frequency dielectric withstand levels for this insulation are in the range of 2 kV to 10 kV rms and shall be agreed upon between the manufacturer and the user. 5.29.4 Continuous current ratings for grounding switches Because of the design features necessary to meet the short-time current ratings, these other currentcarrying duties are not a significant design parameter, and therefore continuous current ratings or design tests are not necessary to verify this capability. Continuous current ratings are not specified for grounding switches. However in certain locations, e.g., at overhead line-entrance terminations, a closed grounding switch in a GIS can be subjected to continuous current due to induction from energized overhead lines running parallel to the line that is grounded. Also, during GIS test procedures (e.g., current injection to ratio-check installed current transformers, measurement of main circuit conductivity, etc.) current-carrying capabilities are required for short durations. 5.29.5 Induced current and voltage interrupting requirements for grounding switches In certain locations, e.g., at overhead line-entrance terminations, a grounding switch in a GIS can be required to interrupt current against recovery voltage due to induction and coupling from energized overhead lines running parallel to the line that is having the ground removed by opening the grounding switch. The requirements for this duty are specified in 6.19 and the rating requirements are specified in 4.11. 5.29.6 Switch position indication/viewports Position indication of grounding switch shall comply with the requirements of 5.28.2. 5.29.7 Operating mechanisms Grounding switch mechanisms shall comply with the requirements of 5.28.3

6. Design tests (type tests) 6.1 General Normally, all tests on GIS components are performed in accordance with the relevant standards for that component. Specific test specifications and/or conditions as defined in this standard supersede those for the specific GIS components. Type tests shall be carried out on a complete functional unit (single-phase or three-phase). Type tests can be made on representative assemblies or sub-assemblies where required by specific tests or conditions.

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IEEE Std C37.122-2010 IEEE Standard for High Voltage Gas-Insulated Substations Rated Above 52 kV

As GIS can be assembled in many configurations of various types, ratings, and combinations of components, it is not practical to type test all possible configurations. Type tests of representative configurations, as appropriate, shall verify performance for other configurations and ratings. The minimum mandatory type tests and verifications are listed in Table 6 below. Table 6 —Listing of minimum mandatory type tests Mandatory GIS type testing Dielectric tests

Subclause 6.2

Power-frequency voltage tests — Lightning impulse voltage tests — Switching impulse voltage tests V (Ur ) > 245 kV — Partial discharge tests — Dielectric tests on auxiliary and control circuits Measurement of resistance of circuits

6.4

Temperature rise tests (continuous current test)

6.5

Short-time withstand current and peak withstand current tests

6.6

Verification of the degree of protection of the enclosure

6.7

Tightness tests

6.8

Electromagnetic compatibility tests (EMC)

6.9

Verification of making and breaking capacities

6.10

Low and high-temperature test

6.11.1

Proof tests for enclosures

6.11.2

Pressure test on partitions

6.12

Tests to prove performance under thermal cycling and gas tightness tests on insulators

6.14

Circuit breaker design tests

6.15

Fault-making capability of high-speed grounding switch

6.16

Switch operating mechanical life tests

6.20

6.1.1 Information for identification of specimens Subclause 6.1.1 of IEEE Std C37.100.1-2007 applies. 6.1.2 Information to be included in type-test reports 15 Subclause 6.1.2 of IEEE Std C37.100.1-2007 applies. In addition the following shall be recorded for bus-transfer switching tests of disconnect switches:

15

Extracts used from Annex A, Annex B, and Annex C of IEC 62271-102 with permission. Copyright © 2001 IEC Geneva, Switzerland. www.iec.ch.

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IEEE Std C37.122-2010 IEEE Standard for High Voltage Gas-Insulated Substations Rated Above 52 kV

a) b) c) d) e) f) g) h) i) j) k)

Typical oscillographic or similar records of the tests performed (at least one oscillogram for each 10 operations) Test circuit Test currents Test voltages Power-frequency recovery voltages Prospective transient recovery voltages Arcing times Number of making and breaking operations Record of the condition of the contacts after test General information concerning the supporting structure of the disconnect switch The operating time of the disconnect switch and the type of operating devices employed during the tests should, where applicable

Also the following shall be recorded for disconnect switch bus charging current switching tests: a) b) c) d) e) f) g) h) i) j) k)

Representative oscillographic record of one make and one break operation Test circuit(s) Steady-state test current (only for test duty 3) Test voltage(s) Transient voltage characteristics Representative record of contact movement Gas fill pressure during the tests Number of make and break switching operations Condition after test Type of fault detection system Supply voltage or pressure of mechanism operated

Also the following shall be recorded for induced current switching tests on grounding switches: a) b) c) d) e) f) g) h) i) j)

Typical oscillographic or similar records Test circuits Test currents Test voltages Power-frequency recovery voltages Prospective transient recovery voltages Arcing times Number of making and breaking operations Condition of grounding switch after test General information concerning the supporting structure of the grounding switch, the operating time of the grounding switch, and the type of operating devices employed during the tests, where applicable

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IEEE Std C37.122-2010 IEEE Standard for High Voltage Gas-Insulated Substations Rated Above 52 kV

6.2 Dielectric tests Subclause 6.2 of IEEE Std C37.100.1-2007 applies. In addition, dielectric tests performed as part of a type test shall be followed by a partial discharge measurement according to the test procedure described in 6.2.9. For power-frequency dielectric testing, frequencies from 48 Hz to 62 Hz are considered equivalent. 6.2.1 Ambient conditions during test Subclause 6.2.1 of IEEE Std C37.100.1-2007 applies. 6.2.2 Wet test (air bushing only) Subclause 6.2.2 of IEEE Std C37.100.1-2007 applies. Wet tests are applicable to GIS to air bushings only. 6.2.3 Conditions of switchgear during dielectric tests Subclause 6.2.3 of IEEE Std C37.100.1-2007 applies. 6.2.4 Criteria to pass the test Subclause 6.2.4 of IEEE Std C37.100.1-2007 applies, except Table 1 of this standard defines the test values. If an insulation failure (disruptive discharge) occurs during type testing an analysis of the cause of failure and method of elimination of the cause shall be made. During dielectric testing, flashover of self-restoring insulation (e.g., in the portion of a gas-air bushing exposed to air) is allowed if the test criteria is met. 6.2.5 Application of the test voltage and test conditions Subclause 6.2.5 of IEEE Std C37.100.1-2007 applies. With single-phase designs (each phase is in an independent grounded metallic enclosure) only tests to ground, and no test between phases, are required. Bushings if used for external connections shall be tested according to the appropriate standards. During all high-voltage tests current transformers shall have their secondaries short-circuited and grounded. If voltage transformers are an integral part of the GIS and have a lower insulation level than the gasinsulated switchgear, then they may be removed during the dielectric tests and replaced by replicas reproducing the field configuration of the high-voltage connections. Overvoltage protection devices, such as surge arresters, shall be disconnected or removed during the tests. If equipment is removed during dielectric testing (e.g., voltage transformers and/or surge arresters) this equipment shall be dielectrically tested in accordance with the relevant standards for each piece of this equipment. 6.2.5.1 General case Subclause 6.2.5.1 of IEEE Std C37.100.1-2007 applies. 6.2.5.2 Special case (Including bias testing) Subclause 6.2.5.2 of IEEE Std C37.100.1-2007 applies.

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IEEE Std C37.122-2010 IEEE Standard for High Voltage Gas-Insulated Substations Rated Above 52 kV

6.2.6 Test of switchgear of V (Ur )  245 kV Subclause 6.2.6 of C37.100.1-2007 applies, except Table 1 of this standard defines the test values. 6.2.6.1 Power-frequency voltage tests Subclause 6.2.6.1 of IEEE Std C37.100.1-2007 applies, except Table 1 of this standard defines the test values. 6.2.6.2 Lightning impulse voltage tests Subclause 6.2.6.2 of C37.100.1-2007 applies, except Table 1 of this standard defines the test values. 6.2.7 Tests of switchgear of rated maximum voltage of V (Ur)> 245 kV Subclause 6.2.7 of IEEE Std C37.100.1-2007 applies, except Table 1 of this standard defines the test values. 6.2.7.1 Power-frequency voltage tests Subclause 6.2 of IEEE Std C37.100.1-2007 applies, except Table 1 of this standard defines the test values. 6.2.7.2 Switching impulse voltage tests Subclause 6.2 of IEEE Std C37.100.1-2007 applies, except Table 1 of this standard defines the test values. 6.2.7.3 Switching impulse voltage tests—phase to phase and isolating distance, above 245 kV Subclause 6.2 of IEEE Std C37.100.1-2007 applies, except Table 1 of this standard defines the test values. 6.2.7.3.1 Dielectric test procedures for three phases in one GIS enclosure 16 If the requirements for phase-to-ground and phase-to-phase insulation levels are different, the test requirements following IEEE Std C37.100.1-2007 have to be reconsidered. This is applicable only for switching impulse tests. 6.2.7.3.2 Application of phase to phase test requirements In order to fully cover the tests to be carried out, Table 7 lists the test conditions in relation to the enclosure, open switching device and phase-to-phase. The table symbols are described in Figure 3. The preferred method is the use of combined voltage test. The voltage levels required may be delivered by two sources in phase opposition connected to the same voltage controller. The total voltage Us from Column 5 of Table 1 shall be composed of 2 components, a switching impulse (main part from Table 1, Column 4) and a power-frequency bias voltage (complementary part) applied as shown in Table 7.

16

Extracts used from Annex A of IEC 62271-203 with permission. Copyright © 2003 IEC Geneva, Switzerland. www.iec.ch.

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IEEE Std C37.122-2010 IEEE Standard for High Voltage Gas-Insulated Substations Rated Above 52 kV

Table 7 —Phase to Phase and isolating distance switching impulse test conditions above 245 kV Test condition Phase-to-phase test

Disconnect switch

Switching impulse withstand Power-frequency withstand voltage Ground Complementary part to Main part of Us between connected to obtain Us phases applied to between phases applied to Aa BbCc F

1

Closed

2

Closed

Bb

AaCc

F

3

Closed

Cc

AaBb

F

4

Open

A

BC

abcF

5

Open

B

AC

abcF

6

Open

C

AB

abcF

7

Open

a

bc

ABCF

8

Open

b

ac

ABCF

9

Open

c

ab

ABCF

NOTE—Test conditions 3, 6, and 9 may be omitted if the arrangement of the outer phases is symmetrical with respect to center phase and the enclosure.

For switching functions and disconnecting functions, respective values have to be taken in Table 1 for open conditions.

Figure 3 —Diagram of connections of a three-pole switching device

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IEEE Std C37.122-2010 IEEE Standard for High Voltage Gas-Insulated Substations Rated Above 52 kV

6.2.7.4 Lightning impulse voltage tests Subclause 6.2.7.3 of IEEE Std C37.100.1-2007 applies, except Table 1 of this standard defines the test values. 6.2.8 Artificial pollution test for outdoor insulators See IEEE PC37.017, Draft 4, February 2010. 6.2.9 Partial discharge tests Partial discharge tests shall be performed and the measurement made in accordance with IEEE Std C37.301. The test may be carried out on assemblies or sub-assemblies of the equipment used for all dielectric type tests. NOTE—Power frequency voltage tests and partial discharge tests can be performed at the same time.

6.2.9.1 Test procedure 17 The applied power-frequency voltage is raised to a pre-stress value which is identical to the powerfrequency withstand voltage test and maintained at that value for 1 min. Partial discharges occurring during this period shall be disregarded. Then, the voltage is decreased to a specific value defined in Table 8 depending on the configuration of equipment and system neutral for partial discharge measurement. The test procedure is illustrated in Figure 4. The partial discharge extinction voltage shall be recorded. Table 8 —Test voltage for measuring partial discharge intensity System with solidly grounded neutral Pre-stress voltage Upre-stress (1 min) Single-phase enclosures design (phase-to-ground voltage)

Upre-stress = Ud

Three-phase enclosures design

Upre-stress = Ud

Ur: Ud: Upre-stress: Upd-test: Upd-test, ph-ea: Upd-test, ph-ph:

17

Test voltage for PD measurement Upd-test (>1 min) Upd-test = 1.2 Ur / 3 Upd-test, ph-ea = 1.2 Ur/ 3 Upd-test, ph-ph = 1.2 Ur

System without solidly grounded neutral Pre-stress voltage Upre-stress (1 min) Upre-stress = Ud Upre-stress = Ud

Test voltage for PD measurement Upd-test (>1 min) Upd-test = 1.2 Ur Upd-test, ph-ea = 1.2 Ur

rated voltage for equipment power-frequency withstand test voltage as per Table 1 pre-stress voltage test voltage for PD measurement test voltage for PD measurement, phase-to-ground test voltage for PD measurement, phase-to-phase

Extracts used from 6.2.9.101 of IEC 62271-203 with permission. Copyright © 2003 IEC Geneva, Switzerland. www.iec.ch.

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IEEE Std C37.122-2010 IEEE Standard for High Voltage Gas-Insulated Substations Rated Above 52 kV

Figure 4 —Partial discharge testing In addition, all components shall be tested in accordance with their relevant standards. 6.2.9.2 Maximum permissible partial discharge intensity 18 The maximum permissible partial discharge level shall not exceed 5 pC at the test voltage specified in Table 8. The value stated above applies to individual components as well as to the sub-assemblies in which they are contained. However, some equipment, such as voltage transformers, have an acceptable level of partial discharge in accordance with their relevant standard greater than 5 pC. Any sub-assembly containing components with a permitted partial discharge intensity greater than 5 pC shall be considered acceptable if the discharge level does not exceed 10 pC. Components for which higher levels are accepted shall be tested individually and shall not be integrated to the sub-assembly during testing. 6.2.10 Dielectric tests on auxiliary and control circuits 19 Auxiliary and control circuits of switchgear and controlgear shall be subjected to short-duration powerfrequency voltage withstand tests. Each test shall be performed a)

between the auxiliary and control circuits connected together as a whole and the grounded frame of the switching device b) if practicable, between each part of the auxiliary and control circuits, which in normal use may be insulated from the other parts, and the other parts connected together and to the frame. The power-frequency withstand voltage tests shall be performed according to IEC 61180-1. The test voltage shall be 2 kV with duration of 1 min. The auxiliary and control circuits of switchgear and controlgear shall be considered to have passed the tests if no disruptive discharge occurs during each test. The test voltage of motors and other devices such as electronic equipment used in the auxiliary and control circuits shall be the same as the test voltage of those circuits. If such apparatus has already been tested in accordance with the appropriate specification, it may be disconnected for these tests. 6.2.11 Voltage test as condition check Subclause 6.2.11 of IEEE Std. C37.100.1-2007 is applicable with the following additions:

18 19

Extracts used from 6.2.9.103 of IEC 62271-203 with permission. Copyright © 2003 IEC Geneva, Switzerland. www.iec.ch. Extracts used from 6.10.6 of IEC 62271-1 with permission. Copyright © 2007 IEC Geneva, Switzerland. www.iec.ch.

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IEEE Std C37.122-2010 IEEE Standard for High Voltage Gas-Insulated Substations Rated Above 52 kV

The test voltage shall be 80% of the value in Table 1, Column 3 for disconnect switches (equipment with safety requirements) and 80% of the value in Column 2 for other equipment. NOTE—Known national exceptions are required for Canada, France, and Italy where it is required by law that the test voltage during condition check across the isolating distance of a disconnect switch be 100% of the rated powerfrequency test voltage.

6.2.12 Insulation paths Subclause 6.2.12 of IEEE Std C37.100.1-2007 does not apply.

6.3 Radio influence voltage (RIV) test Clause 6.3 of IEEE Std C37.100.1-2007 applies for air to gas bushing only.

6.4 Measurement of resistance of circuits Clause 6.4 of IEEE Std C37.100.1-2007 applies. Resistance measurement shall be made on all GIS components before and after the temperature-rise tests and short-circuit tests.

6.5 Temperature rise tests (continuous current test) 6.5.1 Conditions of the switchgear to be tested Subclause 6.5.1 of IEEE Std C37.100.1-2007 applies. 6.5.2 Arrangement of the equipment Subclause 6.5.2 of IEEE Std C37.100.1-2007 is applicable with the following additions: Except in the case when each phase is enclosed individually in a metallic enclosure, the tests shall be made with the rated number of phases and the rated normal current flowing from one end of the buses to the terminals provided for the connection of cables. When a single-phase test is permitted and performed, the current in the enclosure shall be the rated current. When testing individual sub-assemblies, the neighboring sub-assemblies should carry the currents which produce the power loss corresponding to the rated conditions. It is permitted to simulate equivalent conditions by means of heaters or heat insulation, if the test cannot be made under actual conditions. 6.5.3 Measurement of the temperature and temperature rise Subclause 6.5.3 of IEEE Std C37.100.1-2007 applies. 6.5.4 Ambient air temperature Subclause 6.5.4 of IEEE Std C37.100.1-2007 applies. 6.5.5 Temperature-rise testing of the auxiliary and control equipment Subclause 6.5.5 of IEEE Std C37.100.1-2007 applies.

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IEEE Std C37.122-2010 IEEE Standard for High Voltage Gas-Insulated Substations Rated Above 52 kV

6.5.6 Interpretation of temperature-rise tests Subclause 6.5.6 of IEEE Std C37.100.1-2007 is applicable with the following addition: For outdoor application, the manufacturer shall demonstrate that the temperature rise of the equipment will not exceed the limit acceptable under the service condition chosen. The effect of solar radiation shall be taken into account.

6.6 Short-time withstand current and peak withstand current tests Clause 6.6 of IEEE Std C37.100.1-2007 applies. Tests may be made without insulating gas and the enclosure may be open to the atmosphere. 6.6.1 Arrangement of switchgear and of the test circuit 20 Subclause 6.6.1 of IEEE Std C37.100.1-2007 is not applicable. GIS with three-phase enclosures shall be subject to three-phase testing. GIS with single-phase enclosures shall be tested using single-phase with the full return current in the enclosure. The tests shall be made on a representative assembly which should include all types of connections of bolted, welded, plug-in, or otherwise jointed sections to verify the integrity of GIS components are joined together. Assemblies shall be tested such that specimens of all components and sub-assemblies of the design are subjected to the test. Tests shall be made using configurations that provide the most severe conditions. 6.6.2 Test current and duration Subclause 6.6.2 of IEEE Std C37.100.1-2007 applies. 6.6.3 Behavior of switchgear during the test Subclause 6.6.3 of IEEE Std C37.100.1-2007 applies. 6.6.4 Conditions of the switchgear after the test Subclause 6.6.4 of IEEE Std C37.100.1-2007 applies. 6.6.5 Tests on the main circuits 21 After the tests, the resistance measurement shall not vary more than 20% with respect to its pre-test resistance measurement. No deformation or damage to components or conductors within the enclosure, which adversely affect operation, shall have been sustained. Short connections to voltage transformers shall be considered as part of the main circuit, except for parts included in the voltage transformer compartment. 6.6.6 Tests on grounding circuits 22 The manufacturer shall demonstrate the capability of grounding circuits to withstand the rated short-time and peak withstand currents by testing. 20

Extracts used from 6.6.1 of IEC 62271-203 with permission. Copyright © 2003 IEC Geneva, Switzerland. www.iec.ch. Extracts used from 6.6.101 of IEC 62271-203 with permission. Copyright © 2003 IEC Geneva, Switzerland. www.iec.ch. 22 Extracts used from 6.6.102 of IEC 62271-203 with permission. Copyright © 2003 IEC Geneva, Switzerland. www.iec.ch. 21

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IEEE Std C37.122-2010 IEEE Standard for High Voltage Gas-Insulated Substations Rated Above 52 kV

When verification tests are required by the user, grounding circuits of GIS which are factory assembled and comprise grounding conductors, ground connections, and grounding devices shall be tested as installed in the GIS with all associated components which may influence the performance or modify the short-circuit current. After the test, no deformation or damage to the components or conductors within the enclosure which may impair good operation of the main circuit shall have been sustained. Some deformation and degradation of the grounding conductor, grounding connections, or grounding devices is permissible, but the continuity of the grounding circuit shall be preserved.

6.7 Verification of the degrees of protection provided by enclosures Subclause 6.7 of IEEE Std C37.100.1-2007 applies.

6.8 Tightness test 23 Subclause 6.8 of IEEE Std C37.100.1-2007 applies. The measurement of gas tightness shall be performed together with the tests of 6.11.1 and 6.20.2. These tests shall be performed with each type of compartment comprising characteristic sealing of GIS as a type test to show that the leakage rate complies with 5.15, and is not changed by influences caused by the mechanical and limit temperature type tests. 6.8.1 Controlled pressure systems for gas Subclause 6.8.1 of IEEE Std C37.100.1-2007 does not apply. 6.8.2 Closed pressure systems for gas Subclause 6.8.2 of IEEE Std C37.100.1-2007 applies. 6.8.3 Sealed pressure systems Subclause 6.8.3 of IEEE Std C37.100.1-2007 does not apply.

6.9 Electromagnetic compatibility tests Subclause 6.9 of IEEE Std C37.100.1-2007 applies.

6.10 Verification of making and breaking capacities 24 Switching devices forming part of the main circuit of GIS shall be tested to verify their rated making and breaking capacities according to the relevant standards and under the proper conditions of installation and use, i.e., they shall be tested as normally installed in the GIS with all associated components, the arrangement of which may influence the performance, such as connections, supports, etc. NOTE—In determining which associated components are likely to influence the performance, special attention should be given to mechanical forces due to short-circuiting, to the possibility of disruptive discharges, etc. It is recognized that, in some cases, such influences may be negligible.

23 24

Extracts used from 6.8 of IEC 62271-203 with permission. Copyright © 2003 IEC Geneva, Switzerland. www.iec.ch. Extracts used from 6.101 of IEC 62271-203 with permission. Copyright © 2003 IEC Geneva, Switzerland. www.iec.ch.

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IEEE Std C37.122-2010 IEEE Standard for High Voltage Gas-Insulated Substations Rated Above 52 kV

6.11 Mechanical and environmental tests 25 Switching devices of GIS shall be submitted to mechanical operation and environmental tests in accordance with their relevant standards, and shall be tested in a representative assembly of all associated components, which may influence the performance, including auxiliary devices. All equipment shall withstand the stresses caused by the operation of switching devices. 6.11.1 Low and high-temperature test Operation tests at minimum and maximum temperature shall be performed in accordance with the relevant apparatus standards with the following additions: After the test cycles, the following shall be noted: ⎯

The pressure of the gases contained in the enclosure

⎯

The gas leakage over a period of 24 h.

6.11.2 Proof tests for enclosures 26 Proof tests are required when the strength of the enclosure or parts thereof is not calculated. They shall be performed on individual enclosures with testing conditions based on the design pressure stresses. Proof tests may be either a destructive or a non-destructive pressure test, as appropriate to the material employed. 6.11.2.1 Type test pressure test For a pressure type test, rate of change of pressure shall not be greater than 400 kPa/min. The pressure test requirements shall be at least as follows: Cast aluminum and composite aluminum enclosures: Type test pressure = (3.5 / 0.7) × design pressure The value 0.7 has been included to cover the possible variability of production castings. It is permitted to increase this factor to 1.0 if it can be justified by special material tests. Welded aluminum and welded steel enclosures [Equation (1)]:

ª§ 2.3 · § σ t ·º ¸ × ¨¨ ¸¸» × design pressure v © ¹ © σ a ¹¼ ¬

type test pressure = Ǭ

(1)

Where:

ν σt σa 25 26

is the welding coefficient (1 for ultrasonic or radiography inspection of 10% of welded section and 0.75 for visual inspection) is the permissible design stress at test temperature is the permissible design stress at design temperature

Extracts used from 6.102 of IEC 62271-203 with permission. Copyright © 2003 IEC Geneva, Switzerland. www.iec.ch. Extracts used from 6.103 of IEC 62271-203 with permission. Copyright © 2003 IEC Geneva, Switzerland. www.iec.ch.

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IEEE Std C37.122-2010 IEEE Standard for High Voltage Gas-Insulated Substations Rated Above 52 kV

These factors are based on the minimum certified properties of the material used. Additional factors may be required taking into account the methods of construction. No enclosure, after having these test pressures applied, shall be put in normal service or shipped to a user. The criterion for passing this test is no visible yielding of the enclosure. 6.11.2.2 Enclosure non-destructive pressure test 27 In the case of a non-destructive pressure test using a strain indication technique, the following procedure should be applied: Before the test, strain gauges capable of indicating strains to 5 × 10–5 mm/mm shall be affixed to the surface of the enclosure. The number of strain gauges, their position, and their direction shall be chosen so that principal strains and stresses can be determined at all points of importance to the integrity of the enclosure. Hydrostatic pressure shall be applied gradually in steps of approximately 10% of the final design pressure until the standard test pressure for the expected design pressure (see 7.5) is reached or significant yielding of any part of the enclosure occurs. When either of these points is reached, the pressure shall not be increased further. Strain readings shall be taken during the increase of pressure and repeated during unloading. Indication of localized permanent set may be disregarded provided there is no evidence of general distortion of the enclosure. Should the curve of the strain/pressure relationship show a non-linearity, the pressure may be re-applied not more than five times until the loading and unloading curves corresponding to two successive cycles substantially coincide. Should coincidence not be attained, the design pressure and the test pressure shall be taken from the pressure range corresponding to the linear portion of the curve obtained during the final unloading. If the standard test pressure is reached within the linear portion of the strain/pressure relationship, the expected design pressure shall be considered to be confirmed. If the final test pressure or the pressure range corresponding to the linear portion of the strain/pressure relationship (see above) is less than the standard test pressure, the design pressure shall be calculated from the Equation (2):

p=

1 § σa ¨ py 1.1k ¨© σ t

· ¸¸ ¹

(2)

Where:

p py

is the design pressure is the pressure at which significant yielding occurs or the pressure range corresponding to the linear portion of the strain/pressure relationship of the most highly strained part of the enclosure during final unloading (see above)

k

is the standard test pressure factor equaling: 1.3 for welded aluminum and welded steel enclosures 2 for cast aluminum and composite aluminum enclosures

σ a is the permissible design stress at test temperature σ t is the permissible design stress at design temperature 27

Extracts used from 6.103 of IEC 62271-203 with permission. Copyright © 2003 IEC Geneva, Switzerland. www.iec.ch.

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IEEE Std C37.122-2010 IEEE Standard for High Voltage Gas-Insulated Substations Rated Above 52 kV

6.12 Pressure test on partitions 28 The purpose of this test is to demonstrate the safety margin of the partition submitted to pressure in service condition. The insulators shall be installed as for the maintenance condition. The pressure shall rise at a rate of not more than 400 kPa/min until rupture occurs. The rupture pressure shall be greater than three times the design pressure.

6.13 Test under conditions of arcing due to an internal fault 29 Evidence of performance according to 5.20.6 shall be demonstrated by the manufacturer when required by the user. Evidence can consist of a test or calculations based on test results performed on a similar arrangement or a combination of both. If such a test is required, the procedure shall be in accordance with the methods described in Annex B of IEC 62271-203. The short-circuit current applied during the arcing should correspond to the rated short-time withstand current or, in some applications of the switchgear in isolated neutral systems, it may be the ground fault current occurring in such a system. Tests are not necessary in the case of single-phase GIS installed in isolated neutral or resonant grounded systems and equipped with a protection to limit the duration of internal ground faults. Two assessments are made. The first concerns the performance of the equipment during the operation of the first stage (main) protection (see Table 5) and the second concerns the case when the fault is cleared by the operation of the second stage (back-up) protection. In order to verify both assessments, the duration of the test shall be at least equal to the time delay of operation for the second stage of protection. The maximum time setting for the operation of the second stage is defined in Table 5. A shorter test duration can be used if it is not shorter than the operation of the second stage of protection defined by the user. The switchgear should be considered adequate if the performance criteria defined in Table 5 are met.

6.14 Insulator tests Tests on insulators (partitions and support insulators) shall be performed as follows: 6.14.1 Thermal performance The thermal performance of each insulator design shall be verified by subjecting five insulators to ten thermal cycles each. Each thermal cycle shall be as follows: a) b)

28 29

4 hours at minimum ambient air temperature as defined in 2.1 of IEEE Std C37.100.1-2007 for outdoor equipment 2 hours at room temperature

Extracts used from 6.104 of IEC 62271-203 with permission. Copyright © 2003 IEC Geneva, Switzerland. www.iec.ch. Extracts used from 6.105 of IEC 62271-203 with permission. Copyright © 2003 IEC Geneva, Switzerland. www.iec.ch.

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IEEE Std C37.122-2010 IEEE Standard for High Voltage Gas-Insulated Substations Rated Above 52 kV

c) d)

4 hours at limits of temperature and temperature rise according to Table 3 of IEEE Std C37.100.12007 2 hours at room temperature

After the test sequence, all insulators shall recover to the design characteristics. The minimum requirement is that the routine tests shall be withstood. 6.14.2 Tightness test for partitions An overpressure withstand test shall be performed as follows: The design pressure shall be applied on one side of the partition while the adjacent compartment is under vacuum to verify the tightness of a partition. The leakage rate in the compartment under vacuum is measured over a period of 24 h. At the end of the test, no damage shall be observed on the partition. A gas tightness test shall be performed in accordance with 6.8. The leakage rate shall not be greater than the defined value prescribed in 5.15

6.15 Circuit breaker design tests The required tests, test conditions, and testing criteria are established in IEEE Std C37.09.

6.16 Fault-making capability test for high-speed grounding switches This test is required for high-speed grounding switches. This type test is applied to a switch in new condition. Testing criteria: a)

The test will normally be conducted on a single-phase switch unless a group operation is proposed, in which case a three-phase test or equivalent test conditions shall be agreed upon.

b)

The switch shall close against the assigned rated short-circuit making current. Since at these highvoltage ratings full-scale laboratory tests may not be possible, the actual test current shall be the required value with the maximum test circuit voltage available at the test facility. Because of the possible necessity to test at reduced voltage, the manufacturer shall also verify that the performance of the particular switch would be satisfactory at full rated voltage. The methods adopted to provide this additional verification will depend upon the specific details of the grounding switch design and should be the subject of mutual agreement between the manufacturer and the user.

c)

The switch shall be capable of successfully performing two closings onto the rated short-circuit making current. After the first fault-closing, it shall be demonstrated that the switch condition is suitable to permit, without maintenance, immediate return to normal service for a limited time period until the mandatory switch inspection can be scheduled.

Criteria for Passing: After performing the specified operations, the mechanical parts including parts related to the electrical field control (for example field electrode of a GIS grounding switch) and insulators of the grounding switch shall be practically in the same condition as before. Only the short-circuit making performance may be impaired. Mechanically the switch shall operate as before test.

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IEEE Std C37.122-2010 IEEE Standard for High Voltage Gas-Insulated Substations Rated Above 52 kV

In case of doubt, or when the insulating properties across open contacts of a switching device after the making tests cannot be verified by visual inspection with sufficient reliability, a condition checking test according to 6.2.11 (voltage test as condition test) shall be performed.

6.17 Interrupting tests—bus-transfer current switching capability for disconnect switches (special duty only) 30 Rated values for bus-transfer current are given in 4.10. 6.17.1 Bus-transfer making and breaking test procedures—See Annex A 6.17.2 Test duties One hundred make-break operating cycles shall be made. These 100 operating cycles are not considered adequate to demonstrate electrical life but they do provide an indication of contact erosion. The opening operation shall follow the closing operation with a time delay between the two operations at least sufficient for any transient currents to subside. The tests shall be performed without reconditioning of the disconnect switch during the test program. 6.17.3 Behavior of the disconnect switch during tests The disconnect switch shall perform successfully without undue mechanical or electrical distress. 6.17.4 Condition of disconnect switch after tests The mechanical functions and the insulation of the disconnect switch shall be essentially in the same condition as before the tests. The disconnect switch shall be capable of carrying its rated normal current without the temperature rise exceeding the values specified. Evidence of mechanical wear and erosion due to arcing is acceptable as long as it is consistent with the anticipated operating life of the disconnect switch. The quality of the material used for arc extinguishing, if any, may be impaired and its amount reduced below the normal level. There may be deposits on the insulators caused by the decomposition of the arc extinguishing medium. The isolating properties of a disconnect switch in the open position shall not be reduced below what corresponds to normal wear and ageing. Visual inspection and no-load operation of the disconnect switch after tests are usually sufficient for verification of the above requirement. In case of doubt, it may be necessary to perform the appropriate tests for confirmation. In case of doubt, a condition checking test according to 6.2.11 (voltage test as condition test) shall be performed.

6.18 Interrupting tests—switching of bus charging currents by disconnect switches 31 It has been found that, particularly at 420 kV and higher system voltage levels, disruptive discharges to ground might occur when switching small capacitive currents with gas-insulated metal-enclosed switchgear disconnect switches, such as energizing or de-energizing unloaded sections of bus or parallel capacitors of circuit breakers. The test requirements for gas-insulated metal-enclosed disconnect switches 30 31

Extracts used from Annex B of IEC 62271-102 with permission. Copyright © 2001 IEC Geneva, Switzerland. www.iec.ch. Extracts used from Annex F of IEC 62271-102 with permission. Copyright © 2001 IEC Geneva, Switzerland. www.iec.ch.

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IEEE Std C37.122-2010 IEEE Standard for High Voltage Gas-Insulated Substations Rated Above 52 kV

used to switch small capacitive currents (no load currents) such as occur when sections of buses or grading capacitors are energized or de-energized are described here. NOTE—Worldwide investigation has clarified the reasons for this over recent years and given insight into the complexity of very fast transient overvoltage phenomena that occur as an inherent part of capacitive switching with disconnect switches in gas-insulated metal-enclosed switchgear. It was concluded that correct design of the disconnect switch is essential to avoid disruptive discharges to ground.

6.18.1 Type tests Tests for disconnect switches of rated voltages below 300 kV are generally not necessary because the ratios between the specified lightning impulse withstand levels (LIWL) and rated voltages Ur are sufficiently high. 6.18.2 Test duties for making and breaking of bus-charging currents Three test duties are specified: ⎯

Test duty 1: switching of a very short section of bus duct

⎯

Test duty 2: switching of parallel capacitors for circuit breakers under 180° out-of phase condition

⎯

Test duty 3: current-switching capability test

Test duty 1 is a normal type test and is mandatory. Test duty 2 is a special type test to be carried out according to this specification by agreement between manufacturer and user, but it is not necessary if the circuit breaker is not equipped with parallel capacitors. Test duty 3 is a special type test to be carried out according to this specification by agreement between manufacturer and user. It serves only to indicate the current interruption capability of the disconnect switch when de-energizing long buses or other energized parts; for example short length of cables, etc. Typical current values are given in Table 9. 6.18.3 Switching bus charging currents test procedures—See Error! Reference source not found. 6.18.4 Bus charging currents Table 9 —Specified bus charging currents Rated voltage

Ur

(kV rms) Bus charging current (A rms)

2.5

00

23

45

70

45

00

62

20

50

00

.1

.1

.1

.1

.1

.25

.25

.5

.5

.5

.8

NOTE: The values are normally not exceeded in practice.

The values in Table 9 apply to 50 Hz as well as to 60 Hz.

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IEEE Std C37.122-2010 IEEE Standard for High Voltage Gas-Insulated Substations Rated Above 52 kV

6.18.5 Interrupting tests—performance of making and breaking tests 32 During each test duty, the test series shall be performed without reconditioning the disconnect switch. The specified number of tests is given in Table 10. Table 10 —Specified number of tests Test duty

Number of make and break operationsb Standard disconnect switch

Fast-acting disconnect switch a

1

50a

200 a,c

2

50

200

3

50

50

a

Disconnect switches having a contact speed in the range of 1 m/s or higher at the moment of contact separation. If the most onerous disconnect switch arrangement cannot be determined clearly (with reference to 6.18.3), test duty 1 shall be repeated with reversed disconnect switch terminals. c Reduction of the number of tests down to 50 is acceptable if the test voltage is enhanced (to cover statistical effects) to the following values: – source side: U r ×1.2 3 b

–

load side: (dc pre-charge): − U r ×1.2 2

3

6.18.6 Interrupting tests—behavior of the disconnect switch during making and breaking tests 33 The disconnect switch shall perform successfully without mechanical or electrical distress. Disruptive discharges from phase to ground or, in case of three phases in one enclosure, from phase to phase are not permitted. NOTE—It is essential that disruptive discharges to ground or between phases can be detected properly by adequate measuring or detecting equipment.

6.18.7 Interrupting tests—condition after test33 The mechanical functions of the disconnect switch shall be essentially in the same condition as before the test. Evidence of erosion due to arcing and decomposition deposits on insulator surfaces are acceptable, provided the insulating properties of the disconnect switch are not impaired in the open and closed positions. After test duty 1 and test duty 2, no specific action is necessary for verification of this requirement. NOTE—Concerning test duty 3, appropriate verification procedures are under consideration.

6.18.8 Interrupting tests—requirements for measurements33 In general, specialized measurements are required during test duty 1 and test duty 2: ⎯ Measurements of the transient voltage to ground (TVE), U TVE

32 33

Extracts used from Annex F of IEC 62271-102 with permission. Copyright © 2001 IEC Geneva, Switzerland. www.iec.ch. Extracts used from Annex F of IEC 62271-102 with permission. Copyright © 2001 IEC Geneva, Switzerland. www.iec.ch.

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IEEE Std C37.122-2010 IEEE Standard for High Voltage Gas-Insulated Substations Rated Above 52 kV

⎯ Measurements are required in the case of test duty 1 to verify that the load side voltage (U2) meets the specified requirement up to the initiation of the closing operation Requirements for the measurements: ⎯ TVE verification shall be carried out at least once for each test circuit used. Configuration changes such as different connecting lead length, equipment orientation, etc., are considered as changes to the test circuit and will require additional measurements. ⎯ TVE measurements shall be made within 1 m of the arcing contacts of the disconnect switch. If this is not possible, TVE verification may be done by computer calculation, provided that other measurements (within the test section but outside the 1 m zone) are performed at least once to check the validity of the calculation technique. ⎯ Care shall be taken that possible stray power-frequency interference is taken into account. ⎯ TVE measurement shall be made with sufficient bandwidth to record properly the very fast transient (VFT) component.

6.19 Interrupting tests—induced current switching of grounding switches 34 In the case of multiple configurations of overhead transmission lines, current may circulate in deenergized and grounded lines as a result of capacitive and inductive coupling with adjacent energized lines. Grounding switches applied to ground these lines shall therefore be capable of assuring the following service conditions: ⎯ Making and breaking of a capacitive current when the ground connection is open at one termination and grounding switching is performed at the other termination ⎯ Making and breaking of an inductive current when the line is grounded at one termination and grounding switching is performed at the other termination ⎯ Carrying continuously the induced capacitive and inductive currents 6.19.1 Temperature-rise tests Tests will not normally be required since the rated short-time current of the grounding switch may be used to verify that the temperature rises for typical induced current ratings are insignificant. In case of doubt, temperature-rise tests should be performed upon agreement between the manufacturer and the user. 6.19.2 Induced current switching of grounding switches—making and breaking tests— see Annex A Table 11 contains the standardized recovery voltage for electromagnetically induced current, and therefore the grounding switch capabilities for this duty. The prospective TRV waveform may be of a triangular or (1-cos) waveshape. The time to peak is valid for either waveform type.

34

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IEEE Std C37.122-2010 IEEE Standard for High Voltage Gas-Insulated Substations Rated Above 52 kV

Table 11 —Standardized values of recovery voltages for electromagnetically induced current breaking tests Class A Rated voltage Ur (kV)

Powerfrequency recovery voltage (+10/-0%) (kV rms)

TRV peak (+10/-0%) (kV)

72.5

0.5

100

Class B Time to Peak (+0/-10%) (s)

Powerfrequency recovery voltage (+10/-0%) (kV rms)

TRV peak (+10/-0%) (kV)

Time to peak (+0/-10%) (s)

1.1

100

2

4.5

300

0.5

1.1

100

2

4.5

300

123

0.5

1.1

100

2

4.5

300

145

1

2.3

200

2

4.5

300

170

1

2.3

200

2

4.5

300

245

1.4

3.2

200

2

4.5

330

300

1.4

3.2

200

10

23

850

362

2

4.5

325

10

23

1000

420

2

4.5

325

10

23

4000

550

2

4.56

325

20

45

2000

800

2

4.5

325

20

45

2000

NOTE—Recovery voltages are valid for single-phase or three-phase tests.

6.19.2.1 Test duties Ten make-break operating cycles shall be made for each of the electrostatically and electromagnetically induced current making and breaking tests. NOTE—Ten operating cycles are not considered adequate to demonstrate electrical life, but will provide an indication of contact erosion.

The opening operation shall follow the closing operation with sufficient time delay between the two operations for any transient currents to subside. The tests shall be performed without reconditioning of the grounding switch during the test program. 6.19.2.2 Behavior of grounding switch during tests The grounding switch shall perform successfully without undue mechanical or electrical distress. 6.19.2.3 Condition of grounding switch after tests The mechanical functions and the insulation of the grounding switch shall be essentially in the same condition as before the test. The grounding switch shall be capable of carrying rated peak withstand current and its rated short-time withstand current. Evidence of mechanical wear and erosion due to arcing is acceptable as long as it is consistent with the anticipated operating life and maintenance program of the grounding switch. The quality of material used for arc extinguishing, if any, may be impaired and its amount reduced below the normal level. There may be deposits on the insulators caused by the

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IEEE Std C37.122-2010 IEEE Standard for High Voltage Gas-Insulated Substations Rated Above 52 kV

decomposition of the arc extinguishing medium. Visual inspection and no-load operation of the grounding switch after tests are usually sufficient for verification of the above requirements. In case of doubt, a condition checking test according to 6.2.11 shall be performed.

6.20 Mechanical tests for disconnect and grounding switches 6.20.1 Mechanical life test Switches shall be subjected to a mechanical life test consisting of 1000 close-open operations with either manually or power-operated mechanisms supplied at the rated control voltage. Included in the 1000 operations, 50 shall be performed with the maximum control voltage/fluid pressure and 50 at minimum control voltage. The switch shall be in new condition at the commencement of the tests with all essential operating data recorded, e.g., operating time at minimum, rated and maximum control voltage, operating effort required if manually operated, voltage drop or resistance measurements across main contacts, etc. Following the completion of these tests, the switch and operating mechanism shall be in good mechanical condition with no excessive wear. The switch shall operate successfully over the full range of control voltage or, if manually operated, shall not show any significant increase in required operating effort. Measurement of the voltage drop or resistance across the contacts and examination of the contact parts shall confirm that the switch is still able to perform its rated current-carrying duties. If required, a condition checking test according to 6.2.11 shall be performed. Before and after the mechanical operation tests, the measurement of gas tightness according to 6.8 shall be performed to show that the leakage rate is not changed by influences caused by the mechanical life tests. 6.20.2 Operation of mechanical interlocks 35 Disconnect and grounding switches fitted with interlocks shall be submitted to five operating cycles in order to check the operations of the associated interlocks. Before each operation the interlocks shall be set in the position intended to prevent the operation of the switching device. During these tests only normal operating forces shall be employed and no adjustment shall be made to the switching device. The tests are considered satisfactory if the switching devices and the interlocks are in proper working order and if the forces required to operate the switching devices are practically the same before and after the tests.

6.21 Operation at the temperature limits for outdoor equipment (if required by user) By agreement between manufacturer and user a test unit shall be selected from the following: ⎯

Single-phase switch with single-phase mechanism

⎯

Three-phase switch with three-phase mechanism

⎯

Single pole of three-phase switch with mechanism modified to deliver appropriate torque (if required by test chamber limitations only)

The switch, with its mechanism and necessary control equipment, shall be located in a climatic chamber. It shall initially be in the closed position. Heaters, if furnished with the equipment to be provided, may be installed and operated.

35

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IEEE Std C37.122-2010 IEEE Standard for High Voltage Gas-Insulated Substations Rated Above 52 kV

For each of the following temperature conditions, at the end of the required temperature period, the switch shall be operated 3 times each at maximum and minimum supply energy. The operation times for both open and close operations shall be recorded. A gas leakage test shall be performed before and after both the maximum and minimum temperature test series. Minimum temperature test conditions: The chamber temperature shall be lowered to the specified minimum temperature and maintained at that temperature for 12 hours. Maximum temperature test conditions: The chamber temperature shall be raised to the 40 C (or the specified maximum temperature) for a minimum of 4 hours or until the temperature is stabilized.

6.22 Operation under severe ice conditions 36 According to 2.1.2 e) of IEEE Std C37.100.1-2007, three classes of ice coating are specified: ⎯ Class 1 (1 mm ice coating) ⎯ Class 10 (10 mm ice coating) ⎯ Class 20 (20 mm ice coating) 10 mm and 20 mm ice coatings are considered to be representative of severe ice conditions. Disconnect switches and grounding switches having accessories to accommodate a bus-transfer current switching capability (disconnect switches only) and a switching capability of induced currents (grounding switches only) shall be tested with these devices mounted. 6.22.1 Introduction Formation of ice may produce difficulties in the operation of electric power systems. Under certain atmospheric conditions, a deposit of ice can build up to a thickness that sometimes makes the operation of outdoor switching equipment difficult. Nature produces ice coatings which may be divided into two general categories: a) b)

clear ice generally resulting from rain falling through air somewhat below the freezing point of water, and rime ice, characterized by a white appearance, formed for example from atmospheric moisture condensing on cold surfaces.

6.22.2 Applicability The tests defined in this subclause shall be made only if the manufacturer claims suitability of disconnect switches and grounding switches for operation under severe conditions of ice formation. A procedure is described for producing clear ice coatings which compare with those encountered in nature so that reproducible tests can be made. For severe ice conditions, a choice is provided between two classes of ice thickness: 10 mm and 20 mm.

36

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IEEE Std C37.122-2010 IEEE Standard for High Voltage Gas-Insulated Substations Rated Above 52 kV

Disconnect switch commutating contacts for bus-transfer current switching and accessories fitted to grounding switches to accommodate a switching capability of induced currents may not be able to perform these switching capabilities under the severe ice conditions. 6.22.3 Test procedure, formation of ice deposits A coating of solid clear ice of the required thickness, 10 mm or 20 mm, shall be produced. A typical test procedure for the formation of ice is described below. a)

b)

c)

d)

With the test disconnect/grounding switch in the open or closed position, lower the air temperature to 2 °C and start the spray of pre-cooled water. Continue this spray for a minimum of 1 h while holding the air temperature between 0.5 °C to 3 °C. Lower the room temperature to within –7 °C and –3 °C while continuing the water spray. The rate of temperature change is not critical and may be whatever is obtainable with available refrigeration apparatus. Hold the room temperature within –7 °C and –3 °C and continue to spray until the specified thickness of ice can be measured on the top surface of the test bar. The amount of water should be controlled to cause ice to build up over the entire disconnect/grounding switch at the rate of approximately 6 mm/h. Discontinue the spray and maintain the room temperature within –7 °C and –3 °C for a period of at least 4 h. This makes certain that all parts of the disconnect switch and the ice coating have assumed a constant temperature. Following this ageing period, the satisfactory operation of the disconnect/grounding switch, including its auxiliary equipment, shall be checked.

6.22.3.1 Checking of operation If the disconnect or grounding switch is manually operated, the test will be considered as satisfactorily completed if the apparatus has been operated to its final closed or open position, and if it does not sustain damage which may later interfere with its mechanical or electrical performance. If the disconnect or grounding switch is electrically, pneumatically, or hydraulically operated, the test will be considered as satisfactorily completed if the apparatus has been operated on the first attempt up to its final closed or open position by the operating device supplied at its rated voltage or pressure, and if it does not sustain damage which may later interfere with its mechanical or electrical performance. The following tests will demonstrate that the disconnect or grounding switch is able to withstand its rated normal current, rated short-time withstand current, and rated peak withstand current, as applicable: ⎯

Immediately after the closing operation by checking the galvanic contact with a battery and lamp arrangement using a maximum voltage of 100 V

⎯

With the temperature restored to normal ambient by measuring the resistance of the main current path which shall not show significant change

6.22.4 Tests on the power kinematic chain See A.4. 6.22.5 Test results Each test is passed if after the test the position-indicating device indicates correctly the position of the moving contact and there is no permanent distortion on the position-indicating kinematic chain. If a distortion or break occurs in the power kinematic chain upstream of the connecting point, it is permitted to replace components in order to complete the required operations. This shall be mentioned in the type test report.

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IEEE Std C37.122-2010 IEEE Standard for High Voltage Gas-Insulated Substations Rated Above 52 kV

7. Routine testing The following tests shall be routinely performed on each component or assembly during production as noted. In addition routine tests shall be performed on included equipment which design is governed by separate standards (i.e., circuit breakers, instrument transformers, bushings, and surge arresters) in accordance with the applicable standards.

7.1 Dielectric test of main circuit 37 7.1.1 Power-frequency withstand voltage test Dielectric withstand tests shall be performed on each switchgear assembly at the minimum gas pressure. Routine dielectric tests shall be conducted to verify the one-minute withstand level specified in Table 1 for the following conditions: ⎯

Phase to ground

⎯

Phase to phase (if a three-phase enclosure assembly)

⎯

Across open switching device line-to-ground voltage shall be applied (this may be conducted from one side of the switch only)

For power-frequency dielectric testing, frequencies from 48 Hz to 62 Hz are considered equivalent. 7.1.2 Partial discharge testing The measurement of partial discharges shall be performed to detect possible material and manufacturing defects. Partial discharge tests shall be performed in accordance with 6.2.9. The measurement of partial discharges shall be performed with dielectric tests after mechanical routine tests. The test shall be carried out on all components of the gas-insulated switchgear. It may be performed on the complete installation, if applicable, or on transport units or on individual components. Tests on simple components containing no solid insulation may be excluded.

7.2 Tests on auxiliary and control circuits 38 7.2.1 General Inspection of auxiliary and control circuits, and verification of conformity to the circuit diagrams and wiring diagrams shall be made. The nature of the materials, the quality of assembly, the finish and, if necessary, the protective coatings against corrosion shall be checked. A visual inspection is also necessary to check the satisfactory installation of the thermal insulation. A visual inspection of actuators, interlocks, locks, etc., shall be made. Components for auxiliary and control circuits inside enclosures shall be checked for proper mounting. The location of the means provided for connecting external wiring shall be checked that there is sufficient wiring space for spreading of the cores of multi-core cables and for the proper connection of the conductors.

37 38

Extracts used from 7.1 of IEC 62271-203 with permission. Copyright © 2003 IEC Geneva, Switzerland. www.iec.ch. Extracts used from 7.2 of IEC 62271-1 with permission. Copyright © 2007 IEC Geneva, Switzerland. www.iec.ch.

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IEEE Std C37.122-2010 IEEE Standard for High Voltage Gas-Insulated Substations Rated Above 52 kV

The conductors and cables shall be checked for proper routing. Special attention shall be given to make certain that no mechanical damage can occur to conductors and cables due to the proximity of sharp edges or heating elements, or to the movement of moving parts. The identification of components and terminals and, if applicable, the identification of cables and wiring shall be verified. Auxiliary and control circuits shall conform to the schematics, wiring diagrams, and technical data provided by the manufacturer. Technical data may include the number, class, type, capacity of available contacts, and electrical power of shunt releases (other than auxiliary and control contacts, electrical power of shunt releases, etc.). 7.2.2 Functional tests A functional test of all low-voltage circuits shall be made to verify the proper functioning of auxiliary and control circuits in conjunction with the other parts of the switchgear. The test procedures depend on the nature and the complexity of the low-voltage circuits of the device. These tests are specified in the relevant standards for switchgear. They shall be performed with the upper and lower limits values of the supply voltage defined in 4.8.3 of IEEE Std C37 100.1. Operation tests on low-voltage circuits, sub-assemblies and components can be omitted if they have been fully tested during a test applied to the whole switchgear and controlgear. 7.2.3 Verification of protection against electrical shock Protection against direct contact with the main circuit and safe accessibility to the auxiliary and control equipment parts liable to be touched during normal operation shall be checked by visual inspection. Where visual inspection is not considered sufficient, the electrical continuity of grounded metallic parts should be checked by application of a dc current of at least 30 A between the metallic parts and the grounding point. The voltage drop shall be less than 3 V. 7.2.4 Dielectric tests Only power-frequency withstand voltage tests shall be performed. This test shall be made under the same conditions as those detailed in 6.2.10. All control wiring associated with current and linear coupler transformer secondaries and potential device secondaries shall receive a power-frequency withstand test of 2500 V for one minute. All other control wiring shall receive a power-frequency withstand test of 1500 V for 1 min or 1800 V for 1 sec.

7.3 Measurement of the resistance of the main circuit Subclause 7.3 of IEEE Std C37.100.1-2007 applies.

7.4 Tightness tests Leakage tests on the shipping assemblies to confirm compliance with allowable leakage rate shall be performed.

7.5 Pressure tests of enclosures 39 Pressure tests shall be made on enclosures after complete machining. The standard test pressure shall be:

39

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IEEE Std C37.122-2010 IEEE Standard for High Voltage Gas-Insulated Substations Rated Above 52 kV

⎯ 1.3 times design pressure for welded aluminum and welded steel enclosures ⎯ 2 times design pressure for cast aluminum and composite aluminum enclosures The test pressure shall be maintained for at least 1 min. No rupture or permanent deformation should occur during this test.

7.6 Mechanical operation tests 40 Operation tests are made to verify that the switching devices comply with the prescribed operating conditions and that the mechanical interlocks work properly. Switching devices of GIS shall be submitted to a mechanical routine test in accordance with their relevant standards. All position indication devices shall be verified to be in proper working order. The mechanical routine tests can be made before or after assembly of transport units.

7.7 Tests on auxiliary circuits, equipment, and interlocks in the control mechanism 41 All auxiliary equipment shall be tested either by a functional operation or by verification of the continuity of wiring. Settings of relays or sensors shall be checked. The electrical, pneumatic, and other interlocks, together with control devices having a predetermined sequence of operations, shall be tested five times in succession in the intended conditions of use and operation and with the most unfavorable limit values of auxiliary supply. During the test no adjustment shall be made. The tests are considered to be satisfactory if the auxiliary devices have operated properly, if they are in good operating condition after the tests, and if the force to operate the switching device is practically the same before and after the tests. NOTE—These tests may be performed at the installation site if this location is more practical.

7.8 Pressure test on partitions 42 Each partition shall be subjected to a pressure test at twice the design pressure for 1 min in the weakest direction. For the pressure test the partition shall be secured in exactly the same manner as in service. The partition shall not show any sign of overstress or leakage.

8. Gas handling Precautions and requirements for handling sulfur hexafluoride gas (SF6) are discussed in IEC 62271-303 (or IEEE P1712, Draft 7, August 2007). It is important that these precautions and requirements be followed.

9. Field testing The following subclauses establish the requirements for testing the GIS after installation, assembly, and wiring in the field and before placing into commercial service. 40

Extracts used from 7.102 of IEC 62271-203 with permission. Copyright © 2003 IEC Geneva, Switzerland. www.iec.ch. Extracts used from 7.103 of IEC 62271-203 with permission. Copyright © 2003 IEC Geneva, Switzerland. www.iec.ch. 42 Extracts used from 7.104 of IEC 62271-203 with permission. Copyright © 2003 IEC Geneva, Switzerland. www.iec.ch. 41

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IEEE Std C37.122-2010 IEEE Standard for High Voltage Gas-Insulated Substations Rated Above 52 kV

The purpose of these tests is to verify that all the GIS components perform satisfactorily, both electrically and mechanically, after assembly in the field. Field tests provide a method of demonstrating that the GIS apparatus has been assembled and wired correctly. These field tests are to be performed on new installations, additions to existing installations, and recommended after reassembly subsequent to major dismantling for maintenance and repair. The manufacturer and the user should agree on the detailed field testing plan to be used for each GIS installation.

9.1 Mechanical tests: leakage All gas compartments shall be filled with sulfur hexafluoride gas (SF6) or a required gas mixture to the manufacturer’s required rated filling pressure and tested to detect any gas leaks (typically with a hand held gas leakage detector). These leak tests shall include field-assembled enclosure joints, field welds of enclosures, field connected gas monitoring devices, and field connected gas valves and gas piping. By agreement between manufacturer and user, factory assembled joints and special test procedures may be included.

9.2 Mechanical tests: gas quality (moisture, purity, and density) The moisture content of the gas shall be measured prior to energization. In order to get a reliable measurement, the moisture content shall be measured some time after filling as recommended by the manufacturer. The moisture content shall not exceed the limit prescribed by the manufacturer or as agreed to between the manufacturer and user, whichever value is lower. The purity of the gas, as a percentage of SF6, shall be verified prior to energization. The gas purity shall meet the requirements prescribed by the manufacturer. The density of the gas shall be measured and verified to be in accordance with the manufacturer’s nominal rated filling requirements.

9.3 Electrical tests: continuity, conductivity, and resistivity The GIS grounding connections shall be tested for electrical continuity. Resistivity measurements of the main current carrying circuits shall be made on all the bus connecting joints, circuit breakers, disconnecting switches, grounding switches, bushings, and power cable connections to demonstrate and verify that they are within the manufacturer’s specifications. Because live parts are inaccessibile, it is not possible to measure the resistance of individual components. The resistance readings may be obtained for several components connected in series. The manufacturer shall supply factory resistance values of the accessible components in series as a base for verifying test results in the field. The resistivity measurements shall not exceed the maximum values permissible limits (see 7.3) taking into account the differences of the two test arrangements (number of components, contacts and connections, length of conductors, etc.).

9.4 Electrical tests: low frequency ac voltage withstand The gaseous and solid insulation (dielectrics) of the GIS shall be subjected to a low frequency (30 Hz to 200 Hz) conditioning voltage application at voltage levels and durations specified by the manufacturer. The conditioning voltage application shall be followed by a one minute low frequency (30 Hz to 200 Hz) 56 Copyright © 2011 IEEE. All rights reserved.

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IEEE Std C37.122-2010 IEEE Standard for High Voltage Gas-Insulated Substations Rated Above 52 kV

voltage withstand test at 80% of the rated low frequency withstand voltage listed in Table 1. Other tests may be performed subject to user-manufacturer agreements. The conditioning voltage application and the one minute low frequency voltage withstand test shall be performed after the GIS has been completely installed and the gas compartments have been filled to the manufacturer’s recommended nominal rated fill density.

9.5 Electrical tests: low frequency ac voltage withstand requirements and conditions Voltage withstand tests shall be made between each energized phase and the grounded enclosure. For enclosures containing all three phases, each phase shall be tested, one at a time, with the enclosure and the other two phases grounded. The insulation between each two phase conductors are not required to be subjected to any other field voltage withstand tests. Before voltage withstand tests are initiated, all power transformers, surge arresters, protective gaps, power cables, and overhead transmission lines shall be disconnected. Voltage transformers shall be tested up to the saturation voltage of the transformer at the frequency of the test. The voltage shall be applied in steps and gradually raised as specified by the manufacturer to the full field test voltage level (see 9.4). It is possible that a flashover may occur during the application of the conditioning voltage. The acceptability of flashovers during the conditioning voltage application depends on whether the flashover damaged an insulator. The likelihood of such damage is dependent on the voltage level when the flashover occurred, the location in the GIS where the flashover occurred, the length of bus duct connected to the test voltage source, and the particular design characteristics of the insulator. If the GIS successfully withstands the full field test voltage after a conditioning voltage or full field test voltage breakdown has occurred, it can generally be expected that no reduction in dielectric strength has occurred nor will occur in service. A measurement of partial discharges may be performed to detect possible intrusion of conductive particles or damage to high-voltage insulating components occurring during factory testing, transportation, or installation. The gas-insulated switchgear shall be essentially free of partial discharge. The procedure for partial measurement and interpretations shall be provided by manufacturer and agreed between user and manufacturer.

9.6 Electrical tests: low frequency ac voltage withstand configurations and applications When the GIS equipment being tested is connected to GIS apparatus that is in-service, the in-service GIS apparatus shall be electrically isolated from the GIS apparatus to be tested. Suitable grounds shall be applied between the in-service GIS and the GIS to be tested to verify that the test voltage cannot cause service disruptions nor can the service voltage cause severe damage to the testing apparatus or danger to the testing personnel. It is possible that the test voltage is 180 degrees out of phase with the in-service voltage, thereby potentially exposing the open gap of a disconnect switch, being used for isolation, to voltages in excess of what can be withstood. Due to the electrical loading restrictions of the testing apparatus, it may be necessary to isolate sections of the GIS equipment using open disconnects and test each section separately. This may require that portions of the GIS apparatus be subjected to more than one test voltage application. The sections which are not being tested, and which are isolated by a disconnect switch from the section being tested, shall be grounded. The test voltage source may be connected to any convenient point of the phase being tested.

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IEEE Std C37.122-2010 IEEE Standard for High Voltage Gas-Insulated Substations Rated Above 52 kV

9.7 Electrical tests: dc voltage withstand tests A dc voltage withstand test is not recommended on a completed GIS. However, it may be necessary to perform a dc voltage withstand test on power cables connected to a GIS. These test voltages would, by necessity, be applied from the end of the cable opposite from the GIS, therefore subjecting a small portion of the GIS to the dc voltage. It is recommended that the portion of the GIS subjected to this dc voltage be kept as small as possible. The manufacturer should be consulted before performing these tests.

9.8 Electrical tests: assessment of the ac voltage withstand test The switchgear shall be considered to have passed the ac voltage withstand test if each section has withstood the specified test voltage without any disruptive discharge. In the event of a disruptive discharge occurring during dielectric tests on site, the tests shall be repeated.

9.9 Electrical tests: tests on auxiliary circuits Dielectric, continuity, and resistivity tests shall be performed on all interconnecting control wiring installed in the field.

9.10 Mechanical and electrical functional tests: checks and verifications The following shall be verified: a) b) c) d)

e)

f)

g)

h) i)

j) k)

The conformity of the assembly shall be verified to be in accordance with the manufacturer’s drawings and instructions. An external visual inspection to detect defects shall be performed. The torque of all bolts and connections installed in the field shall be verified to be in accordance with the manufacturer’s specifications. The proper function of each electrical, pneumatic, hydraulic, mechanical, key, or combination of interlock methods shall be verified for correct operation in both the permissive and blocking condition. The proper function of the controls, gas, pneumatic, and hydraulic monitoring and alarming systems, protective and regulating equipment, operation counters, including heaters and lights shall be verified. Each mechanical and electrical position indicator for each circuit breaker, disconnect switch, and grounding switch, shall be verified to correctly indicate the device’s position, both open and closed. The conformity of the gas zones, gas zone identification, gas valves, gas valve positions, and interconnecting piping shall be verified to be in accordance with the manufacturer’s and user’s specifications. The operational/function verifications of each circuit breaker, disconnect switch, and grounding switch, shall be performed. Circuit breaker timing tests shall be performed. The correct operation of compressors, pumps, auxiliary contacts, pole disagreement, and antipump schemes shall be verified to be in conformance with the manufacturer’s and user’s specifications The field wiring shall be verified in accordance with the manufacturer’s drawings. The saturation, polarity, turns ratio, and secondary resistance of each current transformer including all connected secondary wiring, shall be verified to be in accordance with the manufacturer’s and user’s specifications

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IEEE Std C37.122-2010 IEEE Standard for High Voltage Gas-Insulated Substations Rated Above 52 kV

l)

The turns ratio and polarity of each tap of each voltage transformer, including all connected secondary wiring, shall be verified to be in accordance with the manufacturer’s and user’s specifications. Secondary voltage measurements shall be made on each tap during the high potential test.

9.11 Mechanical and electrical tests: documentation Equipment ratings and identifications (nameplate data) shall be documented on a form detailing test data and test instruments used. As applicable, each form shall include the following information: a) b) c) d) e) f) g) h) i) j) k) l) m)

Date and time of test Identification of person performing test Humidity, temperature, and barometric pressure Temperature of apparatus being tested Location of apparatus being tested Test equipment used and calibration date Equipment nameplate data Station configuration during test Single line of station Test data Calculations Gas pressure Acceptance criteria

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IEEE Std C37.122-2010 IEEE Standard for High Voltage Gas-Insulated Substations Rated Above 52 kV

Annex A (normative) Switch testing procedures A.1 Bus-transfer making and breaking tests

43

A.1.1 Arrangement of the disconnect switch for tests The disconnect switch under test shall be completely mounted on its own support or on an equivalent support. Its operating device shall be used in the manner prescribed and in particular, if it is power operated, at the minimum supply voltage. Before commencing making and breaking tests, no-load operations shall be made and details of the operating characteristics of the disconnect switch such as speed of travel, closing time and opening time, shall be recorded. Disconnect switch tests shall be performed at the minimum gas density. Disconnect switches having a manual operating device may be operated by remote control using a power operating means such that operating speeds equivalent to those resulting from manual operation are obtained. Tests shall be conducted to prove that a manually operated disconnect switch will operate satisfactorily at the minimum operating speed expected, as stated by the manufacturer. Consideration shall be given to the effects of energization of both terminals of the disconnect switch. When the physical arrangement of one side of the disconnect switch differs from that of the other side, the supply side of the test circuit shall be connected to the side which represents the most onerous condition. In case of doubt, 50% of the breaking and making tests shall be carried out with the supply side of the test circuit connected to one side of the disconnect switch and 50% with the supply connected to the other side. Only single-phase tests on one pole of a three-pole disconnect switch need be performed provided that the pole is not in a more favorable condition than the complete three-pole disconnect switch with respect to: ⎯ Speed of make ⎯ Speed of break ⎯ Influence of adjacent phases Single-phase tests are adequate to demonstrate the making and breaking performance of a disconnect switch. A.1.2 Grounding of the test circuit and disconnect switch The frame of the GIS disconnect switch enclosure shall be grounded. The test circuit shall be grounded as shown in Figure A.1. For gas-insulated disconnect switches, it may be necessary to use an alternative test circuit. See A.1.6.

43

Extracts used from Annex B of IEC 62271-102 with permission. Copyright © 2001 IEC Geneva, Switzerland. www.iec.ch.

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IEEE Std C37.122-2010 IEEE Standard for High Voltage Gas-Insulated Substations Rated Above 52 kV

A.1.3 Test frequency Disconnect switches shall preferably be tested at rated power frequency; however, for convenience of testing, tests may be performed at either 50 Hz or 60 Hz, and are considered to be equivalent. A.1.4 Test voltage The test voltage shall be selected so as to yield the required rated bus-transfer voltage (–0/+10%) across the open disconnect switch terminals as given in Table 3. The test voltage shall be measured immediately after current interruption. As stated in A.1.1, only single-pole tests are normally required. If three-pole tests are required, then the test voltage of each phase shall not differ from the average test voltage by more than 10%. The power-frequency recovery test voltage shall be maintained for at least 0.3 s after interruption. A.1.5 Test current The test current shall be equal to the rated bus-transfer current (–0/+10%) as defined in 6.17. The test current shall be measured before the opening operation of the disconnect switch. The current to be interrupted shall be symmetrical with negligible decrement. The contacts of the disconnect switch shall not be separated until transient currents, due to the closing of the circuit, have subsided. If three-pole tests are performed, the test current is the average of the current in all three poles. The test current for each phase shall not differ from the average test current by more than 10%. A.1.6 Test circuits Field tests or laboratory tests may be made. For laboratory tests, the test circuits A and B, Figure A.1, shall have a power factor not exceeding 0.15. Either test circuit may be used at the convenience of the test laboratory. The characteristic values of the test circuit components, UBT and ZBT, are selected to provide the required test current and the power-frequency recovery voltage. If three-pole tests are required, the three-phase test circuit shall incorporate the same elements in each phase as for the single-phase test circuit in order to yield the appropriate test voltages and currents. The neutral of the supply circuit shall be grounded. Other test circuits may be used which will produce the required test currents and voltages, and the proper transient recovery voltage (TRV) parameters. In the case of gas-insulated disconnect switches the insulation integrity to ground during switching is normally not in question. In case of doubt, tests may be conducted with the rated phase-to-ground voltage of the disconnect switch applied to the enclosure. A separate voltage source may be used. For field tests, it may not be possible to achieve the required tolerances on the test currents and voltages. These requirements may be waived upon agreement between the manufacturer and the user. The prospective TRV waveforms should have the form of a triangular wave due to the surge impedance of the connected bus system. For convenience in testing, however, transient recovery voltages having a (1 – cos) form may be used, having a frequency of not less than 10 kHz and a prospective amplitude factor not less than 1.5. 61 Copyright © 2011 IEEE. All rights reserved.

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IEEE Std C37.122-2010 IEEE Standard for High Voltage Gas-Insulated Substations Rated Above 52 kV

TRV control components may be added to the test circuit. The arc voltage of the disconnect switch under test will typically be relatively high compared to the test voltage. This will result in a significant damping of the TRV and a phase shift in the current such that the test current will be practically in phase with the test voltage. The TRV parameters (rate-of-rise and peak value), therefore, are not significant and a detailed specification is not required.

Figure A.1—Bus-transfer current test circuit for making and breaking tests

A.2 Switching of bus charging currents by disconnect switches 72.5 kV and above 44 A.2.1 Arrangement of the disconnect switch for tests The operating device of the disconnect switch under test shall be operated in the manner specified by the manufacturer and, in particular, if it is power operated, it shall be operated at the specified minimum supply voltage and/or minimum pressure.

44

Extracts used from Annex F of IEC 62271-102 with permission. Copyright © 2001 IEC Geneva, Switzerland. www.iec.ch.

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IEEE Std C37.122-2010 IEEE Standard for High Voltage Gas-Insulated Substations Rated Above 52 kV

Before commencing the making and breaking tests, no-load operations shall be made and details of the operating characteristics of the disconnect switch such as closing time and opening time shall be recorded. Tests shall be performed at the minimum functional density. Associated compartments shall be at their minimum gas density as well. In most cases the physical arrangement of the disconnect switch involves asymmetries (for example asymmetrical shields, or moving contact/fixed contact differences, etc.). For these cases, the arrangement of the disconnect switch shall be such as to perform the test under the most onerous conditions. For test duty 1, the most onerous arrangement is considered to be that which results in maximum pre-striking distance for the closing operation. For test duty 2 and test duty 3, see 6.18.2. The physical arrangement of the disconnect switch is considered to be of minor importance. For disconnect switches having three phases in one enclosure, three-phase tests are desirable. However, single-phase tests, as specified, can be accepted to demonstrate the making and breaking performance. The two remaining phases not involved in the switching process shall be grounded at both terminals. A.2.2 Test frequency Disconnect switches are preferably tested at rated power frequency. For convenience of testing, however, tests may be performed at either 50 Hz or 60 Hz and are considered to be equivalent. A.2.3 Test voltages for making and breaking tests During making and breaking tests the power-frequency voltage shall be maintained for at least 0.3 s before and after the switching operation. In the case of a dc pre-charge voltage at the load side (test duty 1), the dc voltage shall be applied according to the specified level for 1 min before the close operation. The load side shall not be grounded between the open and close operations. The test circuit should not contain elements that cause a decay of the trapped charge. With reference to Figure A.2, Figure A.4, and Figure A.5, the test voltages at source side and load side of the test arrangement shall be applied as given in Table A.1 and are valid for the open disconnect switch. In the case of test duty 3, the test voltage can be higher when the disconnect switch is in the closed position. This is caused by resonance phenomena, especially if the impedance of the supplying transformer is high, which is normal for transformers used for dielectric ac voltage tests. NOTE—The above-mentioned voltage increase will enhance the test conditions. It should not be more than 10%.

Table A.1—Test voltages for making and breaking tests

NOTE 1—Test Ur is the rated voltage. NOTE 2—Test The factor 1.1 has been chosen to take into account statistical effects which are inherent in this kind of switching phenomena, and to restrict the number of test operations to those specified in Table 10. As test duty 3 should only indicate the switching capability of the disconnect this enhancement of the test voltage is not necessary.

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IEEE Std C37.122-2010 IEEE Standard for High Voltage Gas-Insulated Substations Rated Above 52 kV

Figure A.2—Test circuit for test duty 1 A.2.4 Switching of a very short section of bus duct, test duty 1 Figure A.2 shows the test circuit for test duty 1. The load side shall be represented by a section of bus, d2 3 m to 5 m in length. The connection to the supply side shall be realized by another section of bus, d1 in length. In order to obtain representative very fast transient (VFT) conditions, the ratio d2/d1, shall be in the range of 0.36 to 0.52. The source-side circuit shall have an added lumped capacitance, C1. The value of C1 shall be chosen so that the peak value of the voltage to ground at the disconnect switch terminals is met as defined in A.2.5 Before starting a closing operation, the load side shall be charged by dc voltage according to Table A.1, and the dc voltage source disconnected by the auxiliary disconnect switch, DA. Bus lengths d1 and d2 are understood to be taken as the following distances: d1: open contact of the disconnect switch under test (DT) to the bushing connection d2: open contact of the disconnect switch under test (DT) to the open contact of the auxiliary disconnect switch (DA) A.2.5 Transient voltage values The voltage transients at the disconnect switch location during a close operation are used to characterize the behavior of the test circuit and to make certain of consistent overvoltage characteristics under test conditions. Two distinct aspects of transient voltages are of importance: these are the very fast transient (VFT) phenomena and the fast transient (FT) phenomena. The VFT phenomena are determined by the circuit arrangement as described in A.2.4. The circuit response for the fast transient phenomena shall be verified at least once for the test arrangement by direct measurement (see 6.18.8) under the following conditions: ⎯

Source-side test voltage: U r

⎯

Load-side voltage: 0 (no pre-charge)

3

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IEEE Std C37.122-2010 IEEE Standard for High Voltage Gas-Insulated Substations Rated Above 52 kV

or these conditions: the peak value of the transient voltage to ground U TVE at the first prestrike during a close operation shall be not less than 1.4 × U r 2 3 (for practical purposes a variation of 5% is considered acceptable) and the time to peak shall be less than 500 ns (Figure A.3).

Figure A.3—Typical voltage waveform (Including VFT and FT components) A.2.6 Out-of-phase switching, test duty 2 Figure A.4 shows the test circuit for out-of-phase switching. The parallel capacitance CP of a circuit breaker may be represented by the actual circuit breaker or by an adequate capacitance of equal or higher value than the capacitance used in service. The shortest possible connection d3 between capacitor (circuit breaker) and disconnect switch shall be established. The lengths of the other test circuit parts are not specified, but preferably they should be realized as short as possible using standard components. The lumped capacitance C L (Figure A.4) shall be of a value not less than 400 pF. The ratio C1/CL shall be in the range of 4 to 6.

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IEEE Std C37.122-2010 IEEE Standard for High Voltage Gas-Insulated Substations Rated Above 52 kV

Figure A.4—Test circuit for test duty 2 A.2.7 Current switching capability test, test duty 3 The test circuit shown in Figure A.5 applies. For this type of switching, the specific lengths of the bus sections are of no significance. On the load side a lumped capacitance CL shall be added in order to achieve the specified bus-charging current as given in Table 9 with a tolerance of ±10%. In order to reduce resonance effects which can be caused due to a high source impedance, connection of a lumped capacitance C1 of any value is acceptable to the source side.

Figure A.5—Test circuit for test duty 3

A.3 Induced current switching of grounding switches A.3.1 Arrangement of the grounding switch for tests The grounding switch under test shall be installed in the GIS as it will be in service and completely mounted on its own support or on an equivalent support. Its operating device shall be operated in the manner prescribed and, in particular, if it is electrically or pneumatically operated, it shall be operated either at the minimum supply voltage or at the minimum air pressure, respectively.

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IEEE Std C37.122-2010 IEEE Standard for High Voltage Gas-Insulated Substations Rated Above 52 kV

Before commencing making and breaking tests, no-load operations shall be made and details of the operating characteristics of the grounding switch, such as speed of travel, closing time and opening time, shall be recorded. Tests shall be performed at the minimum functional density. Grounding switches having a manual operating device may be operated by remote control utilizing a power operating means such that operating speeds equivalent to those resulting from manual operation are obtained. Tests shall be conducted to prove that a manually operated grounding switch will operate satisfactorily at the minimum operating speed expected, as stated by the manufacturer. Only single-phase tests on one pole of a three-pole grounding switch need be performed provided that the pole is not in a more favorable condition than the complete three-pole grounding switch with respect to ⎯

Speed of make

⎯

Speed of break

⎯

Influence of adjacent phases

Single-phase tests are adequate to demonstrate the making and breaking performance of grounding switch. A.3.2 Grounding of test circuit and grounding switch The test circuit shall be grounded through the terminal of the grounding switch which is normally connected to ground. The frame of the GIS enclosure shall be grounded. A.3.3 Test frequency Grounding switches shall preferably be tested at rated power frequency; however, for convenience of testing, tests may be performed at 48 Hz to 62 Hz. A.3.4 Test voltage The test voltages shall be selected such as to yield the appropriate power-frequency voltage (+10/–0%) across the grounding switch terminals, as shown in Table 11, before making and after breaking. For electromagnetically induced current switching, the test voltage shall be measured immediately after current interruption. For electrostatically induced current switching, the test voltage shall be measured immediately prior to making of the grounding switch. As noted in A.3.1, only single-phase tests are normally required. If three-phase tests are required, then the test voltage of each phase shall not be different from the average test voltage by more than 10%. The power-frequency test voltage shall be maintained for at least 0.3 s after interruption. A.3.5 Test currents The test currents shall be equal to the rated induced currents (–0/+10%) as shown in Table 4. The current to be interrupted shall be symmetrical with negligible decrement. The contacts of the grounding switch shall not be separated until transient currents due to closing of the circuit have subsided.

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IEEE Std C37.122-2010 IEEE Standard for High Voltage Gas-Insulated Substations Rated Above 52 kV

If three-phase making and breaking tests are performed, the test current shall be measured as the average of the current in all three phases. The test current for each phase shall not be different from the average test current by more than 10%. Before contact separation, the waveform of the test current for capacitive current breaking tests shall be, as nearly as possible, sinusoidal. This condition is considered to be satisfied if the ratio of the rms value of the total current to the rms value of the fundamental component does not exceed 1.2. The test current shall not go through zero more than once per half cycle of power frequency before contact separation. A.3.6 Test circuits Field tests or laboratory tests may be made. For laboratory tests, the transmission lines may be replaced by lumped elements consisting of capacitors, inductors, and resistors. If three-phase tests are required, the three-phase test circuit shall incorporate the same elements in each phase as for the single-phase test circuit in order to yield the appropriate test voltages and currents. The neutral of the supply circuit shall be grounded. NOTE 1—Test circuits other than those specified may be used as long as they produce the required test currents and voltages and the proper transient recovery voltage parameters. NOTE 2—For field tests, it may not be possible to achieve the required tolerances on the test currents and voltages. These requirements may be waived upon agreement between the manufacturer and user. It should be noted that if voltage transformers are connected to the grounded voltage line being switched, ferro-resonance may occur during switching depending upon the characteristics of the transformer and the length of the grounded line.

A.3.6.1 Test circuit for electromagnetically induced current making and breaking tests The single-phase test circuit (Figure A.6) consists of a supply circuit yielding the appropriate test voltage and test current such that the circuit power factor does not exceed 0.15. The components R and C are selected to yield the appropriate transient recovery voltage parameters. The damping resistance R may be connected in series or in parallel with the capacitance C. The values of supply voltage (UL) and inductance (L) may be calculated from the values given in Table 4 so as to produce the proper values of test current and power-frequency recovery voltage. The prospective transient recovery voltage waveforms should have the form of a triangular wave due to the surge impedance of the connected transmission lines. For convenience in testing, however, transient recovery voltages having a (1-cos) form may be used. Values of R and C may be selected to yield the proper transient recovery voltage parameters specified in Table 11. A.3.6.2 Test circuits for electrostatically induced current making and breaking test The test circuits 1 or 2 in Figure A.7 can be selected as suitable for the test laboratory, since, as long as the equations within the circuit parameters are satisfied, they are equivalent. The power factor of the test circuit shall not exceed 0.15. The values of supply voltage (UC), inductance L and capacitance C2 for test circuit 1 may be calculated from the given values of C1 in Figure A.7 and the rated current and voltage values in Table 4, by using the equations noted in Figure A.7. This will result in the appropriate values of test current and voltage as well as the proper inrush current frequency and test circuit surge impedance. Values for test circuit 2, Figure A.7, may be calculated from the values derived for test circuit 1, Figure A.7. A resistance (R), not exceeding 10% of the capacitive impedance [ω (C1 + C2 )] = ω ⋅ C1' , as seen from the disconnect switch, may be inserted in the circuits as shown in Figure A.7. The value chosen, however,

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IEEE Std C37.122-2010 IEEE Standard for High Voltage Gas-Insulated Substations Rated Above 52 kV

should not be greater than the surge impedance of the transmission line considered, nor lead to an aperiodic damping of the inrush current when closing the grounding switch. Table A.2—Test circuit capacitances (C1 values) for electrostatically induced current making and breaking tests Test circuit capacitance ±10% Rated voltage Class A

Class B

(μF)

(μF)

72.5

0.07

0.27

100

0.07

0.27

123

0.07

0.27

145

0.13

0.27

170

0.13

0.27

245

0.15

0.27

300

0.15

0.80

362

0.29

1.18

420

0.29

1.18

550

0.35

1.47

800

0.35

1.47

(kV)

NOTE—Values of C1 may be calculated from the expression: C1 = (6D) / (ʌZ0) where D is the line length in km and Z0 is the line surge impedance in Ÿ. Surge impedance assumed: –52 kV to 170 kV: 425 Ÿ; –245 kV to 300 kV: 380 Ÿ; –362 kV to 800 kV: 325 Ÿ.

Figure A.6—Test circuit for electromagnetically induced current making and breaking tests

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IEEE Std C37.122-2010 IEEE Standard for High Voltage Gas-Insulated Substations Rated Above 52 kV

Where: Z0 is the surge impedance of the line: –425 ȍҏ for rated voltages of 52 kV up to and including 170 kV –380 ȍ ҏfor rated voltages of 245 kV up to and including 300 kV –325 ȍ for rated voltages of 362 kV up to and including 800 kV Key: iR is the rated induced current from Table 4 UR is the rated induced voltage from Table 4 C1 is the test circuit capacitance given in Table A.2

Figure A.7—Test circuit for electrostatically induced current making and breaking tests 70 Copyright © 2011 IEEE. All rights reserved.

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IEEE Std C37.122-2010 IEEE Standard for High Voltage Gas-Insulated Substations Rated Above 52 kV

A.4 Tests on the power kinematic chain 45

Key: _________ power kinematic chain -------indicating kinematic chain a) Principle of the mechanical connection b) Measuring phase (except A.4.1) c) Testing phase (except A.4.2) NOTE—Upstream is the sense toward the source of energy, downstream is the sense toward the contacts.

Figure A.8—Position-indicating device A.4.1 Disconnect switches and grounding switches with dependent power operation without strain limiting device Electrical, hydraulic, and pneumatic operating mechanisms: The test shall be carried out according to the following procedure (refer to Figure A.8): a) b)

c)

The power kinematic chain is opened at the opening point. The operating mechanism is supplied with 110% of its rated supply voltage or rated supply pressure and the resulting force (Fm) or torque (Tm) is measured at the opening point after an opening or closing command given to the mechanism. 1.5 Fm or 1.5 Tm is applied at the opening point of the power kinematic chain downstream of the opening point, the disconnect switch or grounding switch being in its relevant test position.

Test results: refer to 6.22.4. The operating mechanism itself may be used to apply 1.5 times the maximum force/torque.

45

Extracts used from Annex A of IEC 62271-102 with permission. Copyright © 2001 IEC Geneva, Switzerland. www.iec.ch.

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IEEE Std C37.122-2010 IEEE Standard for High Voltage Gas-Insulated Substations Rated Above 52 kV

A.4.2 Disconnect switches and grounding switches with dependent manual operation without strain limiting device The test shall be carried out according to the following procedure: a) b)

the disconnect switch or grounding switch is put in the test position; a force of 750 N is applied halfway along the length of the gripping part of the operating handle of the operating mechanism.

Test results: refer to 6.22.4. In the case of a switching device with both types of mechanisms according to A.4.1 and A.4.2, the force/torque to be applied at the opening point shall be the highest value. A.4.3 Disconnect switches and grounding switches with independent power/manual operation with strain limiting device The test shall be carried out according to the following procedure: a) b)

c)

The power kinematic chain is opened at the opening point. The force (Fm) or the torque (Tm) transmitted by the strain limiting device is measured upstream of the opening point while attempting to operate the switching device, either by actuating the power operated mechanism or by hand, until the strain limiting device operates. The operating mechanism is supplied with 110% of its rated supply voltage or rated supply pressure or, in the case of a manual operating mechanism, a force up to the operation of the strain limiting device with a maximum of 750 N is applied halfway along the length of the gripping part of the operating handle of the operating mechanism.S A force of 1.5 Fm or a torque of 1.5 Tm is applied at the opening point of the power kinematic chain downstream of the opening point, the disconnect switch or grounding switch being in its relevant test position.

Test results: refer to 6.22.4. A.4.4 Disconnect switches and grounding switches with independent power/manual operation being actuated by the release of latching devices without strain limiting device The test shall be carried out according to the following procedure: a) b) c) d)

The power kinematic chain is opened at the opening point. The operating energy is stored in the mechanism (the energy may be stored in the operating mechanism either by hand or by power). The mechanism is given an opening or closing command and the resulting force (Fm) or torque (Tm) is measured at the opening point. A force of 1.5 Fm or a torque of 1.5 Tm is applied at the opening point of the power kinematic chain downstream of the opening point, the disconnect switch or grounding switch being in its relevant test position.

Test results: refer to 6.22.4.

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IEEE Std C37.122-2010 IEEE Standard for High Voltage Gas-Insulated Substations Rated Above 52 kV

A.4.5 Disconnect switches and grounding switches with independent power/manual operation with or without strain limiting device The test shall be carried out according to the following procedure: a) b)

The power kinematic chain is opened at the opening point. The operating mechanism is supplied with 110% of its rated supply voltage or rated supply pressure and the force (Fm) or the torque (Tm) transmitted is measured at the opening point.

NOTE 3— Depending on the type of mechanism, the opening or closing command may lead to storing of the operating energy in the mechanism before it is released to the kinematic power chain.

In the case of a manual operating mechanism, a force up to 750 N shall be applied halfway along the length of the gripping part of the operating handle and the force (Fm) or the torque (Tm) transmitted is measured at the opening point of the operating mechanism; NOTE 4—Depending on the type of mechanism, the manual opening or closing operation may lead to the storing of the operating energy in the mechanism before it is released to the kinematic power chain.

A force of 1.5 Fm or a torque of 1.5 Tm, whichever is the highest when both power and manual operation are provided, is applied at the opening point of the power kinematic chain downstream of the opening point, the disconnect switch or grounding switch being in its relevant test position. Test results: refer to 6.22.4.

A.5 Test on the position-indicating kinematic chain When the position-indicating device is marked directly on a mechanical part of the power kinematic chain no test is required. If, during service operations, the part of the position-indicating kinematic chain between the power kinematic chain and the position-indicating device is inside an enclosure providing a minimum degree of protection equivalent to IP2XC of IEC 62271-1 and which has passed a mechanical impact test at a preferred impact level of IK07 according to IEC 62262 with an energy of 2 J, no supplementary tests are required but the following remarks shall be considered. The blows shall be applied to the points of the enclosure that are likely to be the weakest in relation to the protection of the indicating kinematic chain and the indicating device. In all other cases, a test shall be carried out blocking the position-indicating device instead of the moving contact. Test results: refer to 6.22.4.

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