How to judge the quality of a DC motor? How to measure if a DC motor is broken

For DC motors, they can be classified into DC brushed motors and DC brushless motors according to their types. Currently, DC motors are widely used and have penetrated into various industries. So, how to distinguish the quality of DC motors? How to measure good or bad

Generally speaking, first check if there is any wire breakage and if the resistance is normal. If it is a DC brushed motor, you can rotate the rotor and then use a multimeter to test if the output DC is normal. If it is a three-phase brushless DC motor, the rotor can be rotated and the AC voltage output can be measured with a multimeter to see if it is normal. The output voltage is proportional to the speed.

1. Rotate the motor by hand. If there is obvious resistance, it indicates that there is a short circuit inside the motor; If it runs smoothly, it means it is normal.

2. Connect the positive and negative poles, and twisting them by hand will cause significant resistance, indicating that the circuit is normal. If no resistance is felt, it indicates that there is a break point inside.

If it is a DC brushed motor, observe the commutation spark when powered on. If there is no spark, it is normal. If there is a little spark, it is also good. If the sparks are connected into a line and there is a ring fire phenomenon, it cannot be used, otherwise it will shorten the service life of the motor.
After the DC motor runs to a stable temperature rise, the surface temperature of the motor should not exceed 80 degrees Celsius. If it exceeds, it indicates that there is a problem with the motor.

5. After the temperature rise stabilizes, stop the machine and use a multimeter to measure the resistance of the winding. Generally, a few ohms or less is normal.

6. When operating at rated voltage and measuring the speed, the speed deviation should not exceed 10%.

7. Apply 1.2 times the rated voltage, run for 2 minutes, and observe whether the DC motor is running normally.