GE Feeder Management Relay 750 Instruction Manual

GE Multilin 750/760 Feeder Management Relay 8-258 COMMISSIONING TESTS 8.4 PROTECTION SCHEMES8For Delta VTs, use the test connections specified in Figure 8–2: Relay Test Wiring – Delta Connection on page 8–3. A neg-ative sequence voltage can be created by injecting a single phase-phase voltage, or a set of two phase-phase voltages witha known negative sequence component. For a single phase-phase injection the negative sequence voltage magnitude isthe injected voltage divided by .To test Pickup for Delta VTs, use the following procedure:1. Inject a negative sequence voltage of 0 into the bus voltage input of the relay. The Pickup LED should be off.2. Slowly raise the voltage until the Pickup LED comes on. This is the pickup level.3. Lower the voltage until the Pickup LED goes out. This is the reset voltage, which should be 2% of VT less than thepickup level.Indications and Operations are the same as those outlined in Phase TOC 1 on page 8–16.The following procedure checks blocking from logic inputs for Delta VTs:1. Inject voltage to cause a pickup.2. Assert a logic input to provide a "Block Neg Seq Voltage". The Pickup LED should immediately go out.3. Repeat steps 1 and 2 for logic input “Block 1 TRIP Relay” as required.The following procedure checks negative-sequence voltage timing for Delta VTs:1. Connect the “Stop Trigger".2. Set the voltage source to the required test voltage, then turn off the voltage.3. Reset the timer. Turn the voltage on and measure the operating time.4. Repeat Steps 2 and 3 four more times and obtain an average of the time intervals.5. Reset the relay and disconnect the “Stop Trigger".8.4.6 VOLTAGEa) BUS UNDERVOLTAGE (WYE VTS ONLY)To test Bus Undervoltage for Wye VTs, use the test connections specified in Figure 8–1: Relay Test Wiring – Wye Connec-tion on page 8–3.The following procedure checks Pickup with One Phase For Operation:1. Inject Van = Vbn = Vcn = nominal voltage into the bus voltage input of the relay. The Pickup LED should be off.2. Slowly lower Van until the Pickup LED comes on. This is the pickup voltage.3. Continue to lower Van until the Pickup LED goes out. This is the MIN OPERATING VOLTAGE level minus 2% of VT.4. Raise Van until the Pickup LED comes on, and continue to increase until the indicator goes out. This is the reset volt-age, which should be the pickup value plus 2% of VT.5. Repeat Steps 1 through 4 except adjust Vbn and Vcn in turn.The following procedure checks Pickup with Two Phases For Operation:1. Inject Vcn = nominal voltage and Van = Vbn = a voltage between the MIN OPERATING VOLTAGE and the pickup voltageinto the bus voltage input of the relay. The Pickup LED should be on.2. Slowly raise Van until the Pickup LED goes out. This is the reset voltage, which should be the pickup plus 2% of VT.3. Reduce Van until the Pickup LED comes on. This is the pickup voltage of Van.4. Continue to lower Van until the Pickup LED goes out. This is the MIN OPERATING VOLTAGE of Van minus 2% of VT.5. Slowly raise Van until the Pickup LED comes on, then reduce Vbn until the Pickup LED goes out. This is the pro-grammed MIN OPERATING VOLTAGE of Vbn minus 2% VT.6. Slowly raise Vbn until the Pickup LED first comes on and then goes out. This is the reset voltage, which should be thepickup value plus 2% of VT.7. Lower Vbn until the Pickup LED comes on. This is the pickup voltage of Vbn.8. Repeat Steps 1 through 7, substituting Vcn for Van, Van for Vbn and Vbn for Vcn.3