單項(xiàng)選擇題An alternator is being paralleled with one on the lineAt the INSTANT the circuit breaker is closed, the frequency of the incoming alternator will normally （）.

A.increase
B.not change
C.decrease
D.be exactly 60 hertz


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1.單項(xiàng)選擇題Current flowing in only one direction is called （）

A.alternating current
B.omnidirectional current
C.direct current
D.sinusoidal current

2.單項(xiàng)選擇題Accidental grounds in a shipboard electrical system must be repaired as soon as possible as they will （）

A.result in immediate power outages
B.damage circuit breakers
C.appear on the ground detection system
D.damage insulation and may cause outages

3.單項(xiàng)選擇題Prior to closing the breaker when paralleling two AC generators, the recommended practice is to have the frequency of the incoming machine （）

A.slightly less than the line frequency
B.the same as the line frequency
C.slightly greater than the line frequency
D.All of the above

4.單項(xiàng)選擇題Which of the following should be the FIRST step in removing a generator from parallel operation?（）

A.Trip the generator off the switchboard
B.Turn off all electrical equipment
C.Remove the load from the "off going" generator
D.Increase the cycles of the generator staying on the line

5.單項(xiàng)選擇題Electrical power is expressed in （）

A.ohms
B.volts
C.amps
D.watts