Dynamic selection does not fit the motor overload long run, the motor temperature is too high; start too often, short-term or intermittent work quotas for the motor system continuously. You should limit the number of starts, the correct selection of thermal protection, according to the motor calibration scale use.

The second reason is the motor itself Connection error, then the error △ Y-shaped, so that the motor temperature rises rapidly; a stator winding phase short circuit, interturn short circuit or local ground, light the motor overheating, and in severe insulation burn; Squirrel cage rotor broken bars or defective, the motor run 1-2 hours, the rapid rise in core temperature; Ventilation system failure, the fan should be checked for damage, Rotation direction is correct, the ventilation channel is blocked; bearing wear, eccentric rotor sweep chamber so that the rotor core relative to wipe the issue of metal percussion, core temperature rises rapidly, severe motor smoke, or even the coil burnt.

The third reason is the work of environmental Motor winding damp or dust, oil, etc. attached to the winding, resulting in reduced insulation. It should measure the motor insulation resistance and the cleaning and drying treatment; the ambient temperature is too high. When the ambient temperature exceeds 35 ℃, inlet air temperature is high, the high temperature causes the motor, should seek to improve their working environment. Such as scaffolding shade like. NOTE: Because of the electrical aspects of the failure reasons, should be invited to obtain professional qualifications electrical maintenance, do not understand people not blind repair to prevent personal injury accident.

The fourth reason is the power-related Voltage is high or low, in particular load, if the voltage fluctuation range should be outside the + 10% to -5% of the rated value will cause motor overheating; asymmetric power three-phase voltage, three-phase power supply phase voltage imbalance exceeds 5%, will lead the winding overheating; missing running,experience has shown that agricultural motor burned more than 85% is due to missing running caused deal with motor mounting phase protection device.