MV Switchgear Inspection and Test Procedure
1. VISUAL INSPECTION
2. WIRING AND FERRULING CHECK
3. BUS CONTINUITY, PHASING AND CONTACT RESISTANCE TEST
4. CURRENT TRANSFORMER CHECKS
4.1) Visual Inspection
4.2) Insulation resistance test
4.3) Winding resistance measurement
4.4) Polarity test
4.5) Ratio test by current primary injection
4.6) Magnetizing current test (minimum 2 points above )
4.7) Loop resistance measurement test (burden test)
4.8) Phase identification test
4.9) Verify secondary circuits, terminals, shorting/isolating links by primary injection
4.10) High voltage test.
4.11) Single point earthing check
4.12) Demagnetize CT cores after all tests
5. VOLTAGE TRANSFORMER CHECKS
5.1) Winding resistance test
5.2) Insulation resistance test HV/LV/G
5.3) Ratio test
5.4) Polarity test
5.5) Check VT HV neutral solidly grounded
5.6) Verify secondary circuits, terminal to terminal for correctness and tightness
5.7) Loop resistance test and burden test
6. CIRCUIT BREAKER CHECKS
6.1) Visual inspections.
6.2) Contact resistance measurements.
6.3) High- Pot and insulation resistance Test.
6.4) Functional check of trip free and anti pump circuits.
6.5) Functional checks of breaker operation counter.
6.6) Check correct operation of all auxiliary contacts (for breaker open/closed positions).
6.7) Timing test using an electronic oscillograph.
6.8) Check the correct functioning of interlocks and limits switches.
7. TESTING OF METERING ACCURACY BY SECONDARY INJECTION
7.1) Ammeter check
7.2) Voltmeter check
7.3) KWH meter check.
7.4) KW meter check.
7.5) Current transducer check
7.6) Voltage transducer check
7.7) KW transducer check
8. TEST OF PROTECTION RELAYS BY SECONDARY INJECTION
8.1) Over Current Relay
8.2) Earth Fault Relay
8.3) Under Voltage Protection Relay
8.4) Neutral Over Voltage Protection Relay
8.5) Trip Circuit Supervision Relay
8.6) Tripping Relay
9. PRIMARY CURRENT INJECTION TEST
10. HIGH- POT AND INSULATION RESISTANCE TEST
11. FUNCTIONAL CHECK