7SR11 & 7SR12 Commissioning and Maintenance Guide
©2017 Siemens Protection Devices Limited Chapter 6 Page 63 of 72
3.2.2 3 Phase VT fail
Apply 3P balanced nominal voltage and 3P balanced current at a level between the 60VTS Ipps Load setting and
the 60VTS Ipps Fault setting. Reduce the balanced Voltage on all 3 phases until the VTS operates at the 60VTS
Vpps setting. Return the voltage to nominal and ensure that VTS resets.
Reduce the 3P balanced current to a level below the 60VTS Ipps Load setting. Reduce the 3P balanced voltage
to a level below the operate level above. Gradually increase the 3P balanced current until the VTS operates.
Check that the thermal rating of the relay current inputs is not exceeded during the following test. Increase the 3P
balanced current to a level above the 60VTS Ipps Fault setting. Reduce the 3P balanced voltage to a level below
the operate level above. Gradually reduce the 3P balanced current until the VTS operates.
If the VTS can be started from a status input fed from an external source, this functionality should be tested.
Ext_Trig 60VTS Operation □ Not Applicable □
3.2.2.1 Element Blocking
The VT Supervision can be blocked by Binary Input Inhibit. This functionality should be checked.
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