Q.The AC motor does not rotate. Is there any way to check the cause of no rotation?

A.

The causes and how to confirm them are as follows.

Cause Confirmation Method
The system is overloaded
  • Motor temperature is above 90 °C
    (Thermal protector might be working)
  • Confirm if the motor can rotate with no load
  • Are there any factors on the load side could cause an overload (increased weight, catching on the mechanism side, increased frictional force due to aging, etc.)?
  • *Our motor sizing service is available to select the most suitable motor based on the mechanism conditions.
Wrong wiring between power supply and motor, broken wire
  • Confirm the wiring
  • Confirm the actual wiring using a circuit tester
  • Are the switches, relays, etc. used to start and stop the motor broken?
  • *For specific information on how to confirm the wiring, refer to "How to Confirm the Wiring" below.
The product is broken
  • Confirm the winding condition by measuring the motor winding resistance value
  • Confirm the capacitor capacitance
  • Confirm any deterioration to the bearings by turning the motor shaft by hand

[How to check the wiring]

  1. Confirm the wiring
    Please confirm that the wiring diagram in the catalog or operating manual has been followed.

  2. Confirm the actual wiring using a circuit tester
    By using a circuit tester to measure the voltage, you can simply confirm whether the actual wiring is normal or not.

    For Single-Phase Induction Motors and Reversible Motors
    The measurement points are the power supply voltage (circuit tester A below) and the voltage between capacitors (circuit tester B below).
    Perform the measurement with no load or under the rated torque.
    If it's normal, the voltage across the capacitor is measured to be 1.4~1.7 times the power supply voltage.

    • Example of 3 lead wire type, single-phase 100 VAC, CW direction rotation
      Example of 3 lead wire type, single-phase 100 VAC, CW direction rotation
    • Example of 4 lead wire type, single-phase 100 VAC, CW direction rotation
      Example of 4 lead wire type, single-phase 100 VAC, CW direction rotation

    See the video below on measurement method of the voltage across the capacitor and the difference in movement with and without the capacitor.

    Three-Phase Induction Motor
    The measurement points are the power supply voltage (circuit tester A, B, and C below). If normal, all circuit testers show 200 VAC.

    Example of lead wire type, three-phase 200 VAC

Product Category: AC Motors
Model and Series: General
Description: Abnormalities and Problems
FAQ No.: 230

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