Articles on: Learning & FAQ

Why Is There Resistance When Twisting the Shaft of A Stepper Motor by Hand When It Is Not Powered On?

There may be three possible reasons:

1. Short circuit in the motor's coil

In other words, the A+ and A- or B+ and B- of the motor are connected, forming a circuit. Under the action of the permanent magnet, the motor will generate a small amount of torque. This is a normal situation. Usually, we use this method to determine which two wires belong to the same phase.

2. Impurities inside the motor

In this case, the resistance is uneven and random. The impurities that cause this situation may be small iron shavings during the cutting process, or tiny metal impurities in the environment that are adsorbed by the magnet in the rotor during assembly. Since they appear randomly, they may not be detected during factory inspection. In practical applications, the resistance caused by these small impurities will disappear as the motor rotates. However, if the motor is clearly stuck or locked at a certain position, it belongs to a defective motor.

3. The rotor or stator of the motor is displaced by external forces

When the motor is subjected to a large external force, such as falling, impact, or percussion, the shaft, rotor, or stator will be displaced, causing the rotor and stator of the motor to come into contact. This situation should be avoided as much as possible. Of course, this kind of dropping and collision may also occur during transportation. If you find obvious damage to the external packaging and product, please contact our customer service personnel.

Updated on: 04/05/2023

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