单项选择题

Before any work on electrical or electronic equipment is performed, which of the following precautions should be carried out （）

A.De-energize the applicable switchboard bus
B.Bypass the interlocks
C.Secure and tag the supply circuit breaker in the open position
D.Station a man at the circuit supply switch

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单项选择题

Which of the following statements represents the FIRST precaution to be taken prior to working on any installed electrical component （）

A.Wear rubber gloves and boots
B.Use only approved non-conducting tools
C.Ground the case of the machine before beginning any repairs
D.Open the supply circuits and tag the switches

单项选择题

The most common type of AC service generator found aboard ship is the stationary （）.

A.electromagnetic field, revolving armature type
B.electromagnetic field, oscillatory armature type
C.armature, oscillatory electromagnet field type
D.armature, rotating electromagnetic field type

单项选择题

An alternator switchboard has a synchroscope and synchronizing lamps, if the synchroscope is broken, which of the steps listed is the most essential before an alternator can be paralleled with the bus （）

A.The breaker should be closed when one synchronizing lamp is dark and the other is bright
B.The breaker should be closed when both synchronizing lamps are bright
C.The frequency meter should be used to determine that the incoming alternator frequency is slightly higher than the bus
D.A portable phase sequence indicator must be used to verify the information from the lamps