单项选择题
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
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相关考题
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Brushless generators are designed to operate without the use of（）.
A.brushes
B.slip rings
C.commutators
D.all of the above -
单项选择题
It （） for an emergency generator to require paralleling.
A.is usual
B.is not usual
C.is necessary
D.is not impossible -
单项选择题
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
