单项选择题
When paralleling two AC generators, the frequency of the machine coming on-line, immediately prior to closing its breaker, should be （）
A.slightly less than the oncoming generator frequency
B.the same as the bus frequency
C.slightly greater than the bus frequency
D.the same as the bus voltage
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相关考题
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单项选择题
When two AC generators are being paralleled, the breaker should be closed with the synchroscope pointer mating in the （）
A."slow" direction, just before the 12 o'clock position
B."fast" direction, just after the 12 o'clock position
C."fast" direction, just before the 12 o'clock position
D."slow" direction, just after the 12 o'clock position -
单项选择题
AC voltmeters are generally calibrated to read the （）
A.instantaneous voltage
B.average voltage
C.RMS voltage
D.peak voltage -
单项选择题
You are attempting to parallel two AC generators, and the syncope pointer is revolving in the fast directionThis indicates that the frequency of the incoming machine is （）.
A.higher than the bus frequency
B.lower than the bus frequency
C.the same as the bus frequency but out of phase with it
D.the same as the bus frequency and the circuit breaker may be closed at any pointer position
