When the motor temperature exceeds the high working temperature or the temperature rise exceeds the specification or the temperature rise does not exceed the specification, but the temperature rise suddenly increases at low load, it indicates that the motor is faulty. The judgment and elimination methods are as follows:

(1) The temperature rise does not exceed the temperature rise limit under the rated load, and the motor temperature exceeds the allowable operating temperature only because the ambient temperature exceeds 40°C. This phenomenon shows that the motor itself is normal. The solution is to use artificial methods to reduce the ambient temperature. If this is not possible, the load must be reduced.

(2) The temperature rise under rated load exceeds the specification on the nameplate. In any case, the motor is faulty and must be stopped for inspection, especially if the temperature rise suddenly increases. The external reasons are: the grid voltage is too low or the line voltage drop is too large (over 10%), the load is too heavy (over 10%), the motor and the machine are not properly matched; the internal reasons are: single-phase operation, inter-turn short circuit, inter-phase short circuit , The stator is grounded, the fan is damaged or not fastened, the air duct is blocked, the bearing is damaged, the stator and rotor are rubbed, the motor and the cable joint are heated (especially copper-aluminum or aluminum-aluminum connection), the motor is corroded or damp, etc. In addition, in theory, the motor can be forward and reverse, but the fan of some motors is directional. If it is reversed, the temperature rise will exceed a lot. In short, it is necessary to troubleshoot for each specific situation.

With the occurrence of motor failure, the phenomenon of motor overheating generally occurs, and overheating is very detrimental to the insulation of the motor. The part of the motor that is sensitive to the heat reaction is the stator winding insulation. Each insulating material can only withstand a certain temperature. If the temperature exceeds its own allowable temperature, it will accelerate the aging of the insulation and shorten the service life of the motor. Moreover, various insulation damage may occur. accident.

Therefore, the inspection, detection and protection of motor overheating faults are very important to reduce the accident rate, reduce accident losses and improve the economic benefits of enterprises.