What Is Stepper Motor Phase Loss?
Stepper motor phase loss refers to a condition where the current in one motor phase is interrupted during operation, preventing that phase from generating a magnetic field and causing the motor to lose its ability to step properly.
Symptoms of Stepper Motor Phase Loss
- The motor fails to start and only vibrates.
- The motor rotates but with severe vibration, and may oscillate erratically—stepping forward and backward unpredictably.
Note: The symptoms of a stepper motor experiencing phase loss are similar to those of a stalled motor. However, during a phase loss, the motor has no holding torque. You can determine whether the motor has a phase loss or is stalled by checking the holding torque.
Possible Causes of Phase Loss
- Abnormal controller signal: Check whether the controller is faulty.
- Damaged driver: To determine whether the driver's internal circuitry is damaged, perform a swap test by exchanging the driver with a known-good unit.
- Disconnected cable or loose connector: Check whether the cable is disconnected and whether the connector has poor contact.
- Incorrect wiring: Check whether the motor wiring sequence is correct.
- Open internal winding: If all the above checks show no issues, the motor's internal winding is likely open-circuited and the motor may need to be replaced.