單項(xiàng)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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單項(xiàng)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

單項(xiàng)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