Question 275Electricity & Electronics - Assistant Engineer

70% to pass

If a three-phase motor controlled by the control circuit illustrated in figure "B" of the illustration, is running in the forward direction, which of the following sequences must occur before the motor will reverse rotation? Illustration EL-0011

Diagram for USCG Electrical Assistant: If a three-phase motor controlled by the control circuit illustrated in figure...

AFirst, the motor must be stopped via the stop button, then normally open 'F' contacts must re- close, and finally the reverse start button must be depressed.

BFirst, the motor must be stopped via the stop button, then normally closed 'F' contacts must re-open, and finally the reverse start button must be depressed.

CFirst, the motor must be stopped via the stop button, then normally closed 'F' contacts must re-close, and finally the reverse start button must be depressed.

DFirst, the motor must be stopped via the stop button, then normally open 'F' contacts must re- open, and finally the reverse start button must be depressed.

AI Explanation

The correct answer is C) First, the motor must be stopped via the stop button, then normally closed 'F' contacts must re-close, and finally the reverse start button must be depressed. The reasoning is that in order to reverse the rotation of the three-phase motor, the motor must first be stopped. Then, the normally closed 'F' contacts must re-close, which would indicate that the forward direction has been deactivated. Finally, the reverse start button must be depressed to initiate the motor in the reverse direction. The other options are incorrect because they do not follow the proper sequence of events required to reverse the motor's rotation. For example, option A requires the normally open 'F' contacts to re-close, which would not be the correct sequence.

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