The purchase of the motor should follow the "five characters"

The purchase of the motor should follow the "five characters".

A look: look at the appearance of the motor. The surface of the motor is required to be smooth and flat, the nameplate is installed correctly, and the mark is complete (the nameplate should be marked with: model, number, rated power, rated current, rated voltage, temperature rise, connection, speed, noise, frequency, degree of protection, Quality, standard number, working system, insulation grade, production date, manufacturer, etc.; the heat sink of the enclosed motor should be intact and complete.

Two turns: Turn the motor shaft by hand to rotate the motor. The motor with qualified quality should be flexible, no stagnation, no abnormal sound, good inertia, and basically no axial momentum.

Three listening: Just let the motor run on the power supply for 15-25min, listen to the sound of the motor. After the power is turned on, the sound from the motor should be smooth, brisk, and even, so that people can hear the feeling of "machine music." It is usually possible to hear finer "å—¡å—¡" electromagnetic noise and fine "sand" mechanical noise. If there is a squeaky noise such as screaming, dullness, friction, vibration, etc., the motor quality is not good; after the operation is stopped, the motor seat and the end cover should not feel the heat by hand, and the bearing temperature is not high; if you look carefully, there should be no oil leakage. , oil simmering phenomenon.

Four checks: Open the junction box and check the wiring. It is required that the end and end marks of each phase line be clear and complete, and the contact pieces are compacted and compacted, the nuts are complete, and there are grounding bolts.

Five measurements: It is to measure the insulation resistance and current. Using a megohmmeter with a rated voltage of 500v, measure the insulation resistance between the phase line and the phase line and the phase line to the base. The insulation resistance of the qualified motor should be greater than 0.5mω. When the motor is running, use the clamp-type ammeter to measure the current of each phase when the motor is unloaded. The deviation of any one of the three-phase currents from the average value of the three-phase current shall not exceed 10% of the average value, and the no-load current shall be 25 of the rated current. %-50%.