①The power supply.
The voltage is too high or low. Under a certain load, if the voltage fluctuation range is outside the rated value of +10% to -5%, the motor will overheat; the three-phase voltage of the power supply is asymmetrical, and the three-phase voltage imbalance exceeds 5%, which will cause the winding to overheat; Default phase will run, experience has shown that more than 85% of the agricultural motor burned is caused by the default phase operation, and the motor should be equipped with default phase protection device.
②The water pump: the selection of power is not matched, the motor is overloaded for a long time, and the motor temperature is too high; the motor is started too frequently and the rated is short-term or intermittent working continuously. The number of starts should be limited, thermal protection should be selected correctly, and used according to the calibrated rating on the motor.
③The motor itself: the wrong connection method, the wrong connection of the △ shape into the Y shape, makes the motor temperature rise rapidly; the stator winding has interphase short circuit, interturn short circuit or partial grounding, and the motor is locally overheated in mild cases and insulation burns out in severe cases. Broken or defective squirrel cage rotor, the motor runs for 1 to 2 hours, and the iron core temperature rises rapidly; if the ventilation system fails, check whether the fan is damaged, the direction of rotation is correct, and whether the ventilation holes are blocked; the bearing is worn and the eccentric sweeping of rotor makes the stator and rotor iron cores rub against each other and produce a metal impact sound. The temperature of the iron core rises rapidly. In severe cases, the motor emits smoke or even the coil burns.
④The working environment: the motor windings are damp or The dust, oil attaches to the windings, resulting in reduced insulation. The insulation resistance of the motor should be measured and cleaned and dried; the ambient temperature is too high. When the ambient temperature exceeds 35°C, the inlet air temperature will be high, which will cause the temperature of the motor to be too high. Try to improve its working environment. Such as scaffolding and shading.
Note: If a failure occurs due to electrical reasons, an electrician who has obtained a professional qualification certificate should be asked to repair it. People with a little experience should not repair it blindly to prevent personal accidents.