Busbar Protection Stability & Sensitivity Test

This article is about to guide the responsible persons (Electrical Engineers) in conducting Busbar Protection stability & sensitivity test and procedures.

Busbar protection is crucial for the safe and reliable operation of power systems, as it detects and isolates faults in the busbars to prevent damage to equipment and ensure continuity of supply. Testing the stability and sensitivity of busbar protection schemes is essential to verify their performance under various operating conditions and fault scenarios.

Test Equipment: Primary Injection Kit, Clamp Meter and Phase Angle Meter.

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.

ADDITIONAL SAFETY PRECAUTIONS:

1.) LOCKOUT RELAY should be isolated and ensure NO POSSIBLE tripping during the test.
2.) Check that any high impedance protection (ex. Transformer REF protection) is shorted before primary injection on their CT Cores.
3.) Any CT cores not related to bus-bar protection should be shorted for safety.
4.) The injected current should not exceed the smallest turns ratio CT.
5.) Before Stability test , stabilizing resistor to be shorted to avoid any damage for it.
6.) During sensitivity test the CT supervision relay may operate, the test plug should be putted in its test socket to prevent CT shorting during the testing and measuring currents.

Busbar Protection Stability & Sensitivity Test Procedure.

IMPORTANT POINTS should be CONFIRMED Before starting the Busbar stability test:

1. Final setting for Busbar protection relays should be applied and tested.
2. Make sure that star point (of all CTs used for Busbar Protection) are towards Busbar, and it is grounded only in the Busbar protection panels.
3. CT loop test should be checked (High Impedance Busbar)
4. Secondary injection for Busbar CTs should be completed.
5. Resistors (Series and Shunt) settings should be done accurately as per final setting (High Impedance Busbar).
6. CT supervision contacts shall be isolated. (High Impedance Busbar).
7. Confirm the capability of the injection kit. The injection of primary current shall satisfy and exceed 50% of secondary current that will operate the Busbar relay during sensitivity.
8. Confirm that the auxiliary contacts of the double busbar isolators are of Early make, Late break type.
9. The clamp meter should have a direction indication, and this direction must be taken into consideration when measurements.
10. Confirm Metrosil Test.

Inject primary current between feeders 1 and 2 For R Phases,
Measure currents and phase angles in all panels for discrimination zone (for BB 1 & 2) & check zone.

Repeat steps for Y, and B phases and for all feeders and Bus zones.

(in LCC, BBP discrimination zone panels according to BB disconnector which is connected & check zone panel).

TEST RESULTS AND ACCEPTANCE VALUES

The results of testing the Busbar Stability should match what is expected as per the design and implementation of the Busbar Scheme.