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AC Elements

Induction Machine

11.11 Induction Machine You can enter the properties associated with induction machines of the electrical distribution system using this editor. The Induction Machine Editor includes the following thirteen pages of properties: Info Inertia Start Dev. Cable Amp Comment

Nameplate Protection Start Cat. Reliability

Model Load Model Cable/Vd Remarks

11.11.1 Info Page You can specify the induction machine ID, connected Bus, In/Out of Service, Equipment FDR (feeder) Tag, Name, Description, Load Priority, Data Type, Configuration Status, Quantity of Induction Machines, Phase Connection, and Demand Factor within the fields of the Info page.

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ETAP 7.0 User Guide

AC Elements

Induction Machine

Info ID Enter a unique ID with up to 25 alphanumeric characters. ETAP automatically assigns a unique ID to each induction machine. The assigned IDs consist of the default induction machine ID plus an integer, starting with the number one and increasing as the number of induction machines increase. The default induction machine ID (Mtr) can be changed from the Defaults menu in the menu bar or from the Project View.

Bus This is the ID of the connecting bus for the induction machine. If the terminal is not connected to any bus, a blank entry will be shown for the bus ID. To connect or reconnect an induction machine to a bus, select a bus from the list box. The one-line diagram will be updated to show the new connection after you click on OK. Note: You can only connect to buses that reside in the same view where the induction machine resides, i.e., you cannot connect to a bus that resides in the Dumpster or in another composite network. If an induction machine is connected to a bus through a number of protective devices, reconnection of the induction machine to a new bus in this editor will reconnect the last existing protective device to the new bus, as shown below where Mtr3 is reconnected from Bus10 to Bus4.

ETAP displays the nominal kV of the bus next to the bus ID for your convenience.

In/Out of Service The operating condition of an induction machine can be selected by clicking on the buttons for either the In Service or Out of Service options. The properties of an Out of Service machine can be edited like an In Service machine; however, an Out of Service machine will not be included in any System Studies. When the continuity check is activated, an Out of Service machine automatically becomes dimmed in the oneline diagram. Note: The In/Out of Service option is an engineering property, which is independent of the configuration status. Therefore, you can set a branch to be In Service for the Base Data and Out of Service in Revision Data.

Operation Technology, Inc.

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ETAP 7.0 User Guide

AC Elements

Induction Machine

Configuration Select the operating status of the induction machine(s) for the selected configuration status from the list box. Options for operating status include the following: Status Continuous Intermittent Spare

Description Continuously operating load Intermittently operating load Spare load (no short-circuit contribution)

Depending on the demand factor specified for each operating status, the actual loading of the machine is determined for Load Flow and Motor Starting Studies. Note: Status is not a part of the machine engineering properties. For this reason, the name of the configuration status is shown, indicating the machine status under the specific configuration, i.e., you can have a different operating status under each configuration. In the following example, status of a machine is shown to be Continuous under Normal configuration and Spare under Emergency configuration.

Connection Phase This is the phase connection of the induction machine. Select the phase connection type from the list box. Options for phase connection include: Selection 3 Phase 1 Phase

Description 3-phase machine Single-phase machine connected between phase A, B or C. Single-phase machine connected line-to-line between phases AB, BC, or CA

Quantity Enter the quantity (number) of induction machines for this machine ID. This allows you to group identical machines together without a need for graphical presentation in the one-line diagram. View the explanations below to see how ETAP handles Quantity in Load Flow, Short-Circuit, Arc Flash, and Sequence-of-Operation. Load Flow: Notice in the following example of a load flow calculation the current at Bus 2 is equivalent to the sum of each current going to each load at bus 4. This occurs because the quantity of Motor 1 is changed to three. ETAP simulates the effect of what you see in the system powered by U2 without having to display each load.

Operation Technology, Inc.

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ETAP 7.0 User Guide

AC Elements

Induction Machine

In the diagram above, the fuse is red which is showing a critical alert. In the alert view below, Fuse1 is shown to be operating at 156.569. The critical alert for the protective device used on a load with a quantity greater than one is based on the operating current calculated by the characteristics of a single load.

Short-Circuit: In the following Short-Circuit Analysis Motor 1 is contributing 1.13kA to the system. Because Motor 1 has a quantity of three, that current is three times the current that would be seen with a single motor. The load terminal fault current is shown as the current for each load.

Operation Technology, Inc.

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ETAP 7.0 User Guide

AC Elements

Induction Machine

In the diagram above, the fuse is red which is showing a critical alert. In the alert view below, Fuse1 is shown to be operating at 30.645. The critical alert for the protective device used on a load with a quantity greater than one is based on the operating short-circuit current calculated by the characteristics of a single load.

Sequence-of-Operation You cannot run Sequence-of-Operation if you have a Quantity greater than one. Sequence-of-Operation is not used to run simultaneous faults on loads.

Operation Technology, Inc.

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ETAP 7.0 User Guide

AC Elements

Induction Machine

Arc Flash In the following Arc Flash example, the bus Arc Flash characteristics of Bus 2 is equal to Bus 4. The reason is that Motor 1 has a quantity of three which is a quick way of showing what you see in the system under Utility 2.

Operation Technology, Inc.

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ETAP 7.0 User Guide

AC Elements

Induction Machine

The Arc Flash Analysis report shows the incident energy at the terminal of Motor 1 is equal to the incident energy of the terminal at each motor in the equivalent One-Line View. The incident energy of a motor with a quantity greater than one is shown as the incident energy calculated by the characteristics of a single load.

Operation Technology, Inc.

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ETAP 7.0 User Guide

AC Elements

Induction Machine

Equipment Tag # Enter the feeder tag in this field, using up to 25 alphanumeric characters.

Name Enter equipment name, using up to 50 alphanumeric characters.

Description Enter equipment description, using up to 100 alphanumeric characters.

Data Type This field provides a convenient way to track data entry. Select one of the data types (such as Estimate, Typical, Vendor, Final, etc.) from the pull-down list. As the data is updated, this field can be changed to reflect the source of the latest data. There are a total of ten load types. To change the data type names, navigate to the Project Menu, point to Settings and select Data Type.

Priority Select the load priority of this machine from the drop-down list. This field can be used for load priority, operating priority, load-shedding priority, etc. Ten different priorities are allowed. To change priority names, from the Project Menu, point to Settings and select Load Priority.

App. Type Select the application type (either motor or generator) for this induction machine type.

Demand factor Modify the demand factors for Continuous, Intermittent, and Spare status in the provided entry fields. Demand factor is the amount of time the induction machine is actually operating. Demand factor affects the following calculations: x x

Operating kW = Rated kVA * PF * % Loading * Demand Factor Operating kvar = Rated kVA * RF * % Loading * Demand Factor

This pertains when the PF & RF (power factor and reactive factor) are calculated based on the specified % loading from the power factors specified at 100%, 75%, and 50% loading. Demand factors for Continuous, Intermittent, and Spare status have a range from 0% to 100%. Since demand factors are a part of engineering properties, ETAP uses the same factors for all configurations.

11.11.2 Nameplate Page On this page, you can specify the motor nameplate data (ratings). Select Motor Library data, specify % loading, and display motor loading and feeder losses for all Loading Categories.

Operation Technology, Inc.

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ETAP 7.0 User Guide

AC Elements

Induction Machine

Ratings HP/kW Enter the machine output (shaft) rating in horsepower (HP) or kW. You can choose from these two options by clicking on the HP/kW button. ETAP uses the following equations for the nameplate parameters: Rated kVA

= HP * 0.7457/( PF * Eff ) = kW/( PF * Eff )

Full-Load Amp = Rated kVA/(—3 * kV ) = Rated kVA/kV

Rating in HP Rating in kW 3-phase machines Single phase machines

where the PF and Eff are at full load condition (100% loading).

Operation Technology, Inc.

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AC Elements

Induction Machine

MVA/kVA You can toggle between these two options by clicking on the MVA/kVA button. The machine rating will be displayed in MVA or kVA and the machine operating load and feeder losses in (MW + j Mvar) or (kW + j kvar).

kV Enter the rated voltage of the machine in kV. This is a line-to-line voltage for 3-phase machines.

FLA This is the rated full load current of the machine in amperes. This is the current the machine will pull from the system when it is fully loaded (that is, when the system is operating at the rated HP (or kW), rated kV, and rated frequency). When you modify FLA, the machine efficiency at 100% loading is recalculated. ETAP limits the entry of FLA so that the efficiency at 100% loading cannot exceed 100% or be below 10%.

% PF Enter the machine power factor in percent at 100%, 75%, and 50% loading. The power factor at 100% loading is the rated power factor and is used for calculating the rated values. (That is, when you change the power factor at 100% loading, the machine full load current is recalculated.) All three values of the power factors are used for determining the operating power factor of the machine under different percent loading. (In other words, when you change any one of the power factors, the operating load and feeder losses for all loading categories are recalculated.) The sign of a power factor determines whether it is lagging or leading. Since induction machines always take reactive power (kvars) from the system, they have a lagging power factor, which must be entered as a positive value.

% Eff This is the efficiency of the machine, in percent, at 100%, 75%, and 50% loading. Efficiency cannot exceed 100%. The efficiency at 100% loading is the rated efficiency and is used for calculating the rated values, i.e., when you change the efficiency at 100% loading, the machine full load current is recalculated. All three values of the efficiencies are used for determining the machine efficiency under different percent loading, i.e., when you change the value of any one of the efficiencies, the operating load and feeder losses for all loading categories are recalculated.

Rated %Slip and RPM Enter the rated slip or rated RPM (Speed in revolutions per second) for this machine. Slip is in percent. When one of these values is entered, the other is calculated based on the following relation: Rated RPM = (100 - %Slip)*Nominal RPM

where Nominal RPM is calculated based on the poles.

The maximum rated speed is used by ETAP to calculate the torque at full load.

Poles Enter the number of poles. As the number of poles is changed, the synchronous speed of the machine is recalculated and displayed in RPM (revolutions per minute).

Operation Technology, Inc.

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ETAP 7.0 User Guide

AC Elements

Induction Machine

RPM = 120 * Freq./Poles

SF Service factor is the permissible power loading in per unit. Service factor is not used for calculation of loading or feeder losses. ETAP gives you the option to use the service factor for voltage drop calculations of the machine feeder.

Library Access the Motor Nameplate Library data by clicking on the Library button and opening the Library Quick Pick - Motor. Motor Nameplate data can be obtained and substituted from the library by highlighting and double-clicking on the selection. Library data includes motor ratings such as HP/kW, kV, FLA, PF, Eff, and Pole (transferred to the Nameplate page) and motor parameters such as LRC, LR PF, X”, X’, X, X2, X0, X/R, and Td’ (transferred to the Model page). The library selected is displayed next to the library button.

Loading This group is used to assign a percent loading to each one of the ten loading categories for this machine, i.e., each machine can be set to have a different operating loading (generator) level for each loading category. To edit the values of the percent loading, click on any one of the edit fields under the % Loading column. Note: You can select any of these loading categories when conducting Load Flow and Motor Starting Studies. ETAP uses the specified percent loading of each loading category to calculate the operating power factor and efficiency from the values specified at 100%, 75%, and 50% loading. This is accomplished by using a curve fitting technique with a maximum of 100% for power factor and efficiency. The calculated power factor and efficiency are then used to calculate and display the operating kW and kvar loading, as well as the feeder losses, if an equipment cable with a non-zero length is specified for this load.

Operation Technology, Inc.

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ETAP 7.0 User Guide

AC Elements

Induction Machine

Note: Although the demand factor is used for calculating the operating load and feeder losses, the value of the demand factor is not used in determining the operating power factor and efficiency. To edit the loading category names, select Loading Category from the Project Menu.

Operating Load Operating Load can be updated from the Load Flow Study Case Editor. The operating load option is available if your ETAP key has the online (ETAP Management System) feature. When the operating load box is checked in the Load Flow Study Case Editor, the calculation results are updated to sources, loads, and buses, so that they can be utilized as input for later studies. If your ETAP key does not have the online feature, you can see the operating P and Q data in the Element Editor; however, this data cannot be used in a later study.

11.11.2.1 Typical Nameplate Data You can choose from typical nameplate data, once a voltage and kW/HP are specified in a Machine Editor.

NEC NEC data is available for a selected range of machine sizes and voltage levels. NEC specifies an ampacity. ETAP calculates %Efficiency and kVA using the NEC Ampacity value and a typical %Power Factor.

MFR Manufacturer typical data is available for any machine size. Ampacity and kVA are calculated using typical %Power Factor and %Efficiency.

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AC Elements

Induction Machine

Existing A machine is considered to have an existing set of data after NEC or MFR have been selected. You can decide not to update parameters after changing a size or voltage level by choosing to keep the existing set of data.

Library Button This button will bring up the Motor Library Quick Pick.

11.11.3 Model Page

Locked-Rotor % LRC This is the machine locked-rotor current (at motor rated kV) in percent of the rated full load current of the motor.

Operation Technology, Inc.

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AC Elements

Induction Machine

% PF Enter the locked-rotor power factor in percent.

ANSI Short-Circuit Z Std MF/Xsc If you select Std MF, ETAP uses the following ANSI Multiplying Factors for calculating the positive sequence short-circuit impedances. If you select the Xsc option, you can directly enter the short-circuit impedances in percent with motor ratings as the base. Note: The IEC Short-Circuit Method does not use these impedances. Xsc

HP > 1000 HP > 250 HP t 50 HP < 50 HP

kW

RPM

>745.7 > 186.4 t 37.28