An AC motor-driven centrifugal water pump was just started.
During the start, motor current remained peaked for 2 seconds, and then decreased and stabilized at about one-fifth the standard running current.
Normally, the starting current peak lasts about 4 seconds.
Which one of the following could have caused the abnormal start indications above?
A. The pump shaft was initially seized and the motor breaker opened.
B. The pump was initially rotating slowly in the reverse direction.
C. The pump was initially air bound, and then primed itself after 2 seconds of operation.
D. The coupling between the motor and pump shafts was left disconnected after maintenance.
Show Answer
Answer: D
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