單項(xiàng)選擇題Any electric motor can be constructed to be().

A.short proof
B.ground proof
C.explosion proof
D.overload proof


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1.單項(xiàng)選擇題The output voltage of a 440 volt, 60 hertz, AC generator is controlled by the ().

A.prime mover speed
B.exciter output voltage
C.load on the alternator
D.number of poles

2.單項(xiàng)選擇題A ground can be defined as an electrical connection between the wiring of a motor and its().

A.shunt field
B.circuit breaker
C.metal framework
D.inter-pole

3.單項(xiàng)選擇題Brushless generators are designed to operate without the use of().

A.brushes
B.slip rings
C.commutators
D.all of the above

4.單項(xiàng)選擇題It () for an emergency generator to require paralleling.

A.is usual
B.is not usual
C.is necessary
D.is not impossible

5.單項(xiàng)選擇題Usually the panels are interlocked with () so that the devices can be made dead before the doors are opened.

A.protective earth
B.isolators
C.ground switch
D.circuit-breakers