單項(xiàng)選擇題Current changing in direction and rising and falling in value is ().

A.AC
B.DC
C.generator
D.fresh water generator


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1.單項(xiàng)選擇題The output voltage of a three-phase alternator is regulated by the ().

A.AC voltage to the armature
B.AC voltage to the field
C.DC voltage to the armature
D.DC voltage to the field

2.單項(xiàng)選擇題To repair a small electrical motor that has been submerged in saltwater, you should ().

A.wash it with fresh water and apply an external source of heat
B.renew the windings
C.send it ashore to an approved service facility
D.rinse all electrical parts with a carbon tetrachloride cleaning solvent and then blow dry the motor with compressed air

3.單項(xiàng)選擇題A fuse that blows often should be replaced only with a fuse of ().

A.the recommended current and voltage rating
B.higher current and voltage rating
C.higher current and lower voltage rating
D.lower current and higher voltage rating

4.單項(xiàng)選擇題A constant output voltage from an AC generator is maintained by the ().

A.prime mover governor
B.exciter generator
C.voltage regulator
D.reverse power relay

5.單項(xiàng)選擇題What type of rotor is used in split-phase motors?()

A.Dram
B.Salient pole
C.Squirrel-cage
D.Wound-rotor

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