To quickly judge the quality of a motor, you can refer to the following steps:

1. Appearance inspection: First check whether the appearance of the motor is intact, including whether there is obvious damage, deformation, or cracks on the casing. In addition, check whether the motor connection cable is firm and whether it is damaged or worn.

2. High temperature, abnormal noise, and odor: After turning on the motor, pay attention to whether there is an obvious high temperature. Pay special attention to the motor bearings, windings, cooling channels, and other parts. At the same time, pay attention to whether the motor is running with abnormal noise and odor, such as a burning smell or heating of wires.

3. Resistance detection: Use a multimeter to measure the resistance value of the motor winding. Normally, the resistance value should be close to the standard value. If the resistance value is too high or too low, it may indicate a problem with the motor windings, such as an open or short circuit.

4. Winding insulation detection: Check the insulation condition of the motor winding. An insulation resistance tester can be used to measure the insulation resistance value between the motor windings and the housing. The insulation resistance value should reach a certain standard value. If the insulation resistance value is low, it indicates that there is an insulation problem in the winding.

5. Current detection: Measure the running current of the motor by connecting an ammeter. Under normal circumstances, the operating current of the motor should be within the rated current range. If the current is high, it may be due to problems such as excessive motor load or damaged windings.

6. Speed detection: judge the operation of the motor by measuring the speed of the motor. You can use a tachometer or measure vibration to evaluate how well your motor is operating. If the speed is low or there is erratic vibration, it may indicate a motor problem.

7. Resonance detection: Detect whether there is resonance in the motor by tapping the motor shell or using a sound sensor. Resonance phenomena may cause increased vibration and noise, and in severe cases may cause damage to the motor.

The above are some commonly used methods to quickly judge the quality of a motor. If you need a more accurate assessment, you can consider using professional testing equipment and instruments, such as load testers, infrared thermal imaging cameras, etc. In addition, when conducting any tests, be sure to ensure your own safety and never touch moving parts or directly contact electrical equipment to avoid accidents. If you are unsure about the evaluation and judgment of the motor, it is recommended to consult professional motor maintenance personnel or engineers for advice.