MV Switchgear Inspection & Test Procedure!!
VISUAL INSPECTION
WIRING AND FERRULING CHECK
BUS CONTINUITY, PHASING AND CONTACT RESISTANCE TEST
CURRENT TRANSFORMER CHECKS
Visual Inspection
Insulation resistance test
Winding resistance measurement
Polarity test
Ratio test by current primary injection
Magnetizing current test (minimum 2 points above )
Loop resistance measurement test (burden test)
Phase identification test
Verify secondary circuits, terminals, shorting/isolating links by primary injection
High voltage test.
Single point earthing check
Demagnetize CT cores after all tests
VOLTAGE TRANSFORM ER CHECKS
Winding resistance test
Insulation resistance test HV/LV/G
Ratio test
Polarity test
Check VT HV neutral solidly grounded
Verify secondary circuits, terminal to terminal for correctness and tightness
Loop resistance test and burden test
CIRCUIT BREAKER CHECKS
Visual inspections.
Contact resistance measurements.
High- Pot and insulation resistance Test.
Functional check of trip free and anti pump circuits.
Functional checks of breaker operation counter.
Check correct operation of all auxiliary contacts (for breaker open/closed positions).
Timing test using an electronic oscillograph.
Check the correct functioning of interlocks and limits switches.
TESTING OF METERING ACCURACY BY SECONDARY INJECTION
Ammeter check
Voltmeter check
KWH meter check.
KW meter check.
Current transducer check
Voltage transducer check
KW transducer check
TEST OF PROTECTION RELAYS BY SECONDARY INJECTION.
Over Current Relay
Earth Fault Relay
Under Voltage Protection Relay
Neutral Over Voltage Protection Relay
Trip Circuit Supervision Relay
Tripping Relay
PRIMARY CURRENT INJECTION TEST
HIGH- POT AND INSULATION RESISTANCE TEST
FUNCTIONAL CHECK
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