單項(xiàng)選擇題

AC voltmeters are generally calibrated to read the （）

A.instantaneous voltage
B.average voltage
C.RMS voltage
D.peak voltage

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單項(xiàng)選擇題
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
單項(xiàng)選擇題
The voltage developed by an AC generator is controlled by varying the （）
A.speed of the prime mover
B.AC excitation to the field
C.DC excitation to the field
D.DC excitation of the voltage regulator