单项选择题
Equal power factors on paralleled AC generators are maintained by an automatic （）.
A.voltage regulator
B.reverse power relay
C.reverse current relay
D.governor control switch
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相关考题
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单项选择题
To equalize the power factor of two alternators operating in parallel, the （）
A.field excitation of both units is adjusted
B.governors of both units are adjusted
C.phase sequence is altered
D.kilowatt load is evenly divided -
单项选择题
An advantage of DC motors over AC motors is that they （）
A.are less expensive
B.require less maintenance
C.can be started across the line
D.offer a more effective means of controlling speed -
单项选择题
Which of the following devices are protected from being motorized by a reverse-power relay?（）
A.Alternators
B.Wave guides
C.Exciters
D.Amplidynes
