單項(xiàng)選擇題As a general rule, the first troubleshooting action to be taken in checking faulty electric control devices is to （）.

A.draw a one line diagram of the circuitry
B.test all fuses and measure the line voltage
C.take megger readings
D.insulate the apparatus from ground


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1.單項(xiàng)選擇題A circuit breaker differs from a fuse in that a circuit breaker （）.

A.melts and must be replaced
B.is enclosed in a tube of insulating material with metal ferrules at each end
C.gives no visual indication of having opened the circuit
D.trips to break the circuit and may be reset

2.單項(xiàng)選擇題Voltage generated by most AC generators is fed from the machine to the bus by means of（）.

A.brushes on a commutator
B.brushes on slip rings
C.slip rings on a commutator
D.direct connections from the stator

3.單項(xiàng)選擇題Electrical leads and insulation on a motor should be painted with（）.

A.heat-resisting acrylic
B.heat-resisting aluminum
C.insulating varnish
D.insulating white lead

4.單項(xiàng)選擇題The electrolyte in a lead-acid storage battery consists of distilled water and （）.

A.hydrogen chloride
B.calcium chloride
C.sulfuric acid
D.muriatic acid

5.單項(xiàng)選擇題A circuit breaker and a fuse have a basic similarity in that they both （）.

A.can be reset to energize the circuit
B.should open the circuit when overloaded
C.will burn out when an over current flow develops
D.All of the above