Testing directional overcurrent and earth fault protection relays (67/67N) involves several steps to ensure their proper functioning.
This article is to guide the responsible persons in conducting Directional Overcurrent and Earth Fault Protection relay (67/67N) Commissioning and test procedure.
Test Equipment:Â 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 Overcurrent and Earth Fault Protection relay (67/67N) Test.
Here’s a general outline and steps of the test procedure:
- Perform General Visual Inspection as per work instructions.
- Perform the tests required as per the following test connection for injection of secondary Current values to the relay:
- Check the directional operating characteristic angle (forward, reverse and undefined).
- Check the polarizing voltage (3Uo) Pick up and Drop off.
- Check Earth fault over current group (non-directional & directional element).
- Repeat step for different curves (NI, EI, LTI, DT,..etc) as per requirement or as indicated in the Test form.
- Check the communication Fail.
- Check all Tele-Protection Schemes (Blocking, Unblocking, Directional Comparison, Direct Transfer Trip).
It’s essential to follow manufacturer-specific testing procedures outlined in the relay’s manual and adhere to any industry standards and guidelines applicable to protective relay testing. Additionally, experienced personnel with a thorough understanding of protective relay principles should conduct these tests.