單項選擇題The energy consumed by an AC motor, as strictly reactive power, is （）

A.used to do mechanical work
B.used to establish the magnetic field of the motor
C.lost as heat generated by the windings
D.lost in doing work to turn the motor itself


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1.單項選擇題A diesel driven emergency generator is prevented from being paralleled with the ships service generators by （）

A.an electrical interlock system
B.an automatic paralleling trip switch
C.the synchronizing oscilloscope
D.the reverse current relay

2.單項選擇題A motor enclosure which protects against falling liquids is classified as （）

A.waterproof
B.drip proof
C.spray tight
D.spray proof

3.單項選擇題Universal motors will operate on AC or DC current, and are generally found in （）

A.portable tools
B.large pump motors
C.turbo electric main motors
D.forced draft fans

4.單項選擇題An operational amplifier, as used in todays consoles, has a calculated gain of 5This means that when the input changes （）

A.5 volts, the output changes 10 volts
B.10 volts, the output changes 5 volts
C.2 volts, the output changes 10 volts
D.10 volts, the output changes 2 volts

5.單項選擇題Electrical failures in motors are caused by the breakdown of insulation, which may be caused by （）

A.penetration of moisture
B.accumulation of dirt
C.overheating
D.All of the above