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P544/6 (with Distance)

12

Chapter 6 - Current Differential Protection

STUB BUS DIFFERENTIAL PROTECTION

This product can provide stub-bus protection associated with the differential protection. If you wish to use this feature you must ensure that the current differential protection is enabled. You will need to map one of the opto-isolated inputs to the DDB Stub Bus Enabled using the programmable scheme logic and you will need to enable the feature by setting Ph Diff Stub Bus in the CURRENT DIFF column to Enabled. When the stub bus protection is enabled and activated by energisation of the opto-isolated input, the differential protection is disabled. No differential trip signals will be issued by the affected terminal. No differential intertrip signals will be issued, or acted upon by the affected terminal. No permissive intertrip signals will be issued, or acted upon by the affected terminal. Intertripping signals mapped via IM64 will be acted upon, and the affected terminal remains active to protect the isolated stub bus. For products having two sets of CT inputs, the stub bus protection takes the two sets of current inputs and uses them as inputs to the phase differential current protection. The values are compared against the dual slope characteristics to determine whether tripping should occur or not. For products having a single set of CT inputs, an additional setting (Ph Is1 StubBus) is provided. In these applications, if the stub-bus feature is enabled and activated, the protection will trip if the measured current exceeds the Ph Is1 StubBus setting. Tripping due to the operation of the stub-bus protection is always three-phase. The principle is outlined in the figure below: To busbar 1

CTX1

P54x

Communication channel

P543/5

End Y

CT Y End X

Protected line CTX2

To busbar 2

V02614

Figure 43: Stub Bus protection Note: Models having distance protection feature a phase segregated stub bus protection associated with the distance protection elements. Where applicable these are described along with the distance elements.

P544 6Z-EN-TM-N

115