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單項選擇題

Complete maintenance of electrical motors should include periodic checks for machine （）

A.vibration
B.watertight integrity
C.speed droop
D.reactive power

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單項選擇題

The frequency of an alternator is controlled from the main switchboard by adjusting the（）

A.frequency meter
B.voltage regulator
C.governor control
D.sychroscope switch

單項選擇題

The frequency of an AC generator is controlled by the （）

A.rheostat
B.governor
C.exciter
D.capacitor