Скачать или смотреть 11KV VCB testing Methods Interview Questions and Answers - தமிழ்

11KV VCB testing Methods Interview Questions and Answers

Click here
👇👇👇

https://electrical4learning.blogspot....

Vacuum Integrity Test
👇👇👇👇

   • VCB Vacuum Circuit Breaker Maintenance, Va...  

Testing of an 11kV Vacuum Circuit Breaker (VCB) ensures its reliability, safety, and performance. The following are standard testing methods for 11kV VCBs:

1. Visual Inspection & Mechanical Tests

General Inspection: Check for damages, loose connections, or corrosion.

Mechanical Operation Test: Open and close the breaker multiple times to verify smooth operation.

Interlocking Mechanism Test: Ensure proper working of mechanical and electrical interlocks.

2. Insulation Resistance Test (Megger Test)

Measures insulation resistance between:

Phase to phase

Phase to earth

Across open contacts

Test Equipment: Megger (5kV or 10kV)

Acceptable Range: Typically greater than 1000 MΩ

3. Contact Resistance Test

Measures resistance across closed contacts to detect any degradation.

Test Equipment: Micro-ohmmeter

Acceptable Value: Typically less than 100 µΩ

4. High Voltage (Dielectric) Withstand Test

Primary Injection Test: Apply high voltage between phases and earth to check insulation strength.

Test Voltage:

Power Frequency Withstand Test: 28kV AC for 1 minute

Lightning Impulse Test: 75kV peak

Equipment: High Voltage Test Set

5. Vacuum Interrupter Integrity Test (Hi-Pot Test)

Determines whether the vacuum interrupter is intact.

Test Voltage: 40kV DC for 11kV VCB

Pass Criteria: No breakdown or flashover

6. Timing Test (Operating Time Test)

Checks breaker opening, closing, and total trip time.

Standard Values:

Closing Time: 30-80 ms

Opening Time: 20-60 ms

Test Equipment: Circuit breaker timer

7. Contact Travel Analysis Test

Measures parameters like:

Contact movement

Stroke

Overtravel

Bounce time

Test Equipment: Motion analyzer

8. Current Injection Test (Primary & Secondary)

Primary Injection Test: Inject high current to verify CT ratio and protection relay response.

Secondary Injection Test: Simulate fault currents through relay and ensure proper tripping.

9. SF6 Gas Leakage Test (If Applicable)

If the breaker has SF6 insulation, test for gas leakage using a gas detector.

10. Functional & Protection Relay Test

Verifies proper relay operation by injecting test signals.

Ensures coordination with the protection system.

Conclusion

Performing these tests periodically ensures the safety, reliability, and longevity of the 11kV VCB. The test results should be compared with manufacturer specifications and international standards like IEC 62271.

Would you like a detailed procedure for any specific test?