Motor detection method: 1. Insulation detection: Use an insulation resistance meter (megger) to detect the motor casing and winding resistance values, and determine whether there is a leakage of short circuit to the casing. Detect the resistance value between winding resistances to determine if there is a short circuit between winding resistances 2. The detection of winding resistance value can generally be preliminary tested with a multimeter to determine whether there is a short circuit, open circuit fault, etc. in the winding resistance 3. The no-load current detection uses a clamp meter to measure the no-load current of the motor, which is generally 40% to 55% of the rated current. The main reasons for excessive no-load current are poor internal iron core of the motor, large gap between the rotor and stator, insufficient coil turns, and incorrect winding connection 4. Measure the resistance value of the single-phase motor at the common end and the main and secondary windings in pairs, where the sum of the two numbers equals the third resistance value, which is normal, i.e. (R1=R2+R3). If any resistance value is infinite, it indicates an open circuit situation

5. The resistance value of the three-phase motor should be measured in pairs with three leads, and their resistance values should be equal, that is, R1=R2=R3 is normal