When two synchronous generators parallel running,there must have ( ).
A. equal voltage/equal current/ equal frequency
B. equal voltage/ equal frequency
C. equal current/ equal frequency
D. equal active power/ equal reactive power
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For essential loads onboard the ship, they are directly fed by main switchboard, so as to ( ).
A. Save money
B. easy operation
C. enhance the reliability of essential loads
D. improve the useage of essential loads
( ) are powered directly by the main switchboard.
A. deck machineries
B. low capacity load
C. some essential loads
D. stationary submersible pump
A three-phase asynchronous induction motor running in a three-phase insulated ship power system, only the stator single-phase winding and the grounded shell are short-circuited accidentally, then ( ).
A. fuses will blow out
B. thermal relay will act
C. not affected
D. large grounded current will occur
Protection that cannot be done by air circuit breaker alone is ( ).
A. undervoltage protection
B. overload protection
C. reverse power protection
D. short circuit protection
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