單項選擇題The frequency of the alternating current generated by a synchronous generator is governed by the speed and the（）

A.full excitation
B.load
C.power factor
D.number of poles


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1.單項選擇題When two DC generators operate in parallel, they are protected against motorizing by（）

A.blow out coils
B.governor relay
C.under voltage trips
D.reverse current trips

2.單項選擇題The correct phase rotation of a three-phase alternator can be checked with a（）

A.dynamometer
B.power factor meter
C.three-phase motor
D.polyphase voltmeter

3.單項選擇題A probable cause for a turbo generator tripping out on overspeed is a sudden（）

A.loss of field excitation
B.total loss of load
C.large increase in load
D.loss of steam pressure

4.單項選擇題All of the following operating characteristics are listed on the name-plates of motors used aboard ship except the（）

A.temperature rise
B.input kilowatts
C.horsepower
D.operating voltage

5.單項選擇題When would you ground an electric hand tool?（）

A.When it is a DC machine
B.When it is an AC machine
C.Any machine that operates on over 100 volts
D.Only when working on wet steel plates