ELECTRICAL TESTS HIGH VOLTAGE DEAD TANK SF6 CIRCUIT BREAKERS

HIGH VOLTAGE DEAD TANK SF₆ CIRCUIT BREAKERS

VISUAL INSPECTION

Inspect for physical damage and nameplate compliance with single line diagram.

Check special tools are supplied.

Inspect primary bushings/porcelains for cracks and damage.

Inspect external primary contact adapters etc. for damage and proper installation.

Inspect SF₆ piping, filling valves and pressure gauges and overpressure relief diaphragm.  Verify that an isolation valve is fitted that allows removal of the pressure gauge etc. without depressurizing the circuit breaker.

Check for adequate electrical and mechanical clearances.

Check mounting frame and supports.

Check Door seal.  Check for proper lubrication of the mechanism, and that mechanism parts are rust free.  Check auxiliary switch configuration.

MECHANICAL INSPECTION HIGH VOLTAGE DEAD TANK SF6 CIRCUIT BREAKERS

Check the operating mechanism for friction.

Check the phase drive linkages.

Check the trip mechanism, latch load, and sneak settings if applicable.

Check manual close, latch and trip operation if applicable.

Check trip free operation if applicable.

Check auxiliary switches for proper operating sequence, good contact alignment, and proper adjustment of the operating linkage.

Check terminal blocks and connections.

Check the mechanical condition of auxiliary devices, shock absorbers, bumpers, position indicators, latch checking switches, key lock out, etc.

Check air receivers, accumulators, associated pipe work and gauges and lockout functions on hydraulic or pneumatic operating mechanisms as applicable. 

Check for SF₆ leaks using sniffer or gas detector.  Check SF₆ operating lockout functions and alarms, SF₆ dew point and final SF₆ operating pressure.

Check and record opening and closing speed (timing) of the circuit breaker.

ELECTRICAL TESTS HIGH VOLTAGE DEAD TANK SF6 CIRCUIT BREAKERS

Check bonding and ground connections.  Verify correct preparation of primary circuit aluminum connections. 

Measure and record contact resistance of each pole with the test probes connected to the bushing contact adapters.  Values must be consistent with manufacturers recommendations.

Perform Doble insulation power factor tests.

High Potential Testing:  Consult PDD or CSD specialists for applicability and test voltages.  DC testing must not be performed.

Check space heater functioning.  Verify wire numbering.  Megger test circuit breaker control wiring per recommended values in P-000.

Close and open the breaker using the control switch, trip the breaker from each protective relay and trip device.

Auxiliary protective devices, such as ground fault or under voltage relays, shall be activated to insure operation of shunt trip devices.

Report/investigate unusual noises after energization (e.g. CT vibration).

TEST DATA

High Potential Test (Per manufacturer’s instructions if necessary to perform)