單項(xiàng)選擇題The unit "hertz" is equivalent to （）

A.coulombs per second
B.revolutions per second
C.revolutions per minute
D.cycles per second


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1.單項(xiàng)選擇題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

2.單項(xiàng)選擇題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