Directional Negative Phase Sequence Overcurrent Relay (67Q) Test.

Testing the Directional Negative Phase Sequence Overcurrent Relay (67Q) is essential to ensure its reliable operation in detecting and protecting against negative sequence overcurrent faults in power systems.

This article is to guide the responsible persons in conducting Directional Negative Phase Sequence Overcurrent Relay (67Q) Test.

Test Equipment: Secondary Injection test kits; Multimeter; Digital Timer.

Safety Precautions: The following Safety precautions shall be taken in consideration prior, during and after conducting the test measurements.

• Safety tagging shall be implemented.
• Isolate the Area by Safety Warning Tape.
• Keep a Safe Distance from the device being tested.
• Wear Appropriate Personal Protective Equipment(PPE) Prior to starting any testing activity.
• Implementation of Proper Grounding.

Directional Negative Phase Sequence Overcurrent Relay (67Q) Test Procedure.

Below is a detailed guide step by step on how to perform testing for the 67Q relay:

1. Perform General Visual Inspection as per work instructions.
2. Perform the tests required as per the following test connection for injection of secondary Current values to the relay:

3. Adjust relay time setting as instantaneous zero seconds. Adjust the tester direction angle as forward direction. Check Pick-up & Drop off Values of the Current and voltage, for all phases and select type of fault for testing. Percentage error (% error) = (measured – expected) /expected
4. Check test results for operating pick up values according to simulated fault types as the following:
   Single phase to earth fault: the injected current at which the protection will operate = 3 (expected setting pick up current value).
   Phase to phase fault: the injected current at which the protection will operate = √3 (expected setting pick up current value).
   3 phase fault: the relay will not operate.
5. Check the directional operating characteristic angle by injecting suitable value of voltage and 1.5 of operating pick up value of current. And start from angle =∟0° to Check test results and characteristic for 360°∟determination operating and blocking
   areas.
6. Repeat step for different curves (NI, EI, LTI, DT,..etc) as per requirement or as indicated in the Test form.
7. Check Leds for MCB /VT failure or fuse failure.
8. Check leds for faulted phase identification /phase selection.

By following above steps and conducting thorough testing, you can ensure the reliable operation of the Directional Negative Phase Sequence Overcurrent Relay (67Q) and its effectiveness in protecting power systems against negative sequence overcurrent faults.