Certified Maintenance and Reliability Technician (CMRT) Practice Test

Question: 1 / 400

How can you change the rotation of a three-phase motor?

Change any two leads

To change the rotation of a three-phase motor, the most effective method is to change any two leads of the power supply connecting the motor. In a three-phase system, the direction of the magnetic field produced by the motor’s windings determines the rotation direction of the motor. By swapping any two of the three power leads, the phase sequence is altered, which in turn reverses the direction of the magnetic field and consequently the rotation of the motor.

Changing the motor direction switch would not necessarily be applicable to all motor designs and may not effectively achieve the desired outcome. Adjusting the input frequency affects the motor speed but does not inherently change its rotation direction. Modifying the motor's internal wiring typically involves complex changes that aren't practical for simply reversing rotation. Therefore, the simplest and most reliable method of reversing a three-phase motor's direction is indeed to switch any two leads in the power supply.

Get further explanation with Examzify DeepDiveBeta

Reverse the motor direction switch

Adjust the input frequency

Modify the motor's internal wiring

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