Page 386 - Offshore Electrical Engineering Manual

Closing and Tripping 373

CLOSING AND TRIPPING

The protection relays are fault sensing devices and cannot interrupt fault currents
themselves. Therefore it is vital that the operation of the devices which perform
this duty, i.e., the circuit breakers and their tripping and closing control circuits,
are checked with their associated protection relay schemes. For the circuit breakers
to be operated, it is necessary to commission the tripping and closing batteries and
chargers before the primary injection test. An auxiliary DC supply is often required
by the protection relays, in any case, for the operation of indication devices and as
power supplies for electronic relays.
All auxiliary relays associated with each circuit breaker control system, including
lockout relays and intertripping and interlocking schemes, should be functionally
tested before the circuit breaker is put into service.