表面粗糙度的高度评定参数为((______ ))(Rz)( )。
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同步步并车时,常观察整步表指针转动情况合闸。合闸时刻应是____。
A. 顺时针转动(大约3-5秒转一周)到同相位点位置
B. 逆时针转动(大约3-5秒转一周)到同相位点位置
C. 顺时针转动(大约3-5秒转一周)到11点位置
D. 逆时针转动(大约3-5秒转一周)到11点位置
在电动机控制线路中,时间继电器的缩写是 ( )。
A. KM
B. KA
C. KT
D. QF
For two generators running in paralel, if the RMS value of the voltage, frequency and the current are all at nominal value, but the readings of the two power factor meter are not the same, it means that ( ).
A. both the distributions of the active power and reactive power are even.
B. the active power distribution is even, the reactive power distribution is uneven.
C. the active power distribution is uneven, the reactive power distribution is even
D. both the distributions of the active power and reactive power are uneven
三相异步电动机星-三角降压起动实验中时间继电器进行了两次时间整定,分别为____。
A. 1s,5s
B. 2s,8s
C. 3s,6s
D. 5s,10s