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
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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
For the following statement about the adjustment method of the time relay, ( ) are correct. ① when adjusting, generally only adjust according to the value indicated on the dial; ② when adjusting, increase the delay time by clockwise direction; ③ when adjusting, increase the delay time by counterclockwise direction; ④ the sets must be verified after adjustment
A. ①②
B. ②③
C. ②④
D. ③④
For a 3-phase induction motor, the working voltage has declined by 10 percent of nominal voltage, it's torque should declined by ( ) percent of nominal torque.
A. 10%
B. 20%
C. 30%
D. 40%
Nominal secondary voltage of commonly used voltage transformer is ( ). when N1 /N2= 10000/100,measurable maximum voltage in parallel with secondary winding is ( ).
A. 100V / 1000V
B. 100V / 10000V
C. 500V / 5000V
D. 500 / 50000 V