Several common causes and treatment methods of water pump motor overheating

When a water pump gets hot during operation, it usually means that there is something wrong with the water pump. The normal operation of the water pump should be within the appropriate temperature range, and overheating can be caused by a variety of reasons. This article will explore the possible reasons for the water pump to get hot and the countermeasures to help everyone understand and solve this problem.

• Power supply reasons:

The voltage is too high or too low. Under a specific load, if the voltage variation range is between +10% and -5% of the rated value, it will cause the motor to overheat. The three-phase voltage of the power supply is asymmetric, and the phase imbalance of the three-phase voltage of the power supply exceeds 5%, which will also cause the winding to overheat. Experience shows that more than 85% of agricultural motors burn out due to phase loss operation, and a phase loss protection device must be installed.

• Causes of pump failure:

Power selection is not matched, a small horse pulls a big cart, the motor is overloaded for a long time, causing the motor temperature to be too high; starting too frequently, and the motor is continuously working in a short-term or intermittent working mode. The number of starts should be limited, and the thermal protector should be correctly selected and used according to the rated power of the motor.

• Electrical reasons:

Incorrect wiring, mistakenly connecting the △ shape to the Y shape, causing the motor temperature to rise rapidly; the stator winding has phase-to-phase short circuit, turn-to-turn short circuit or partial grounding, which may cause partial overheating of the motor at the least, or insulation burnout in severe cases. The squirrel cage rotor is broken or defective, and the core temperature rises rapidly after the motor runs for 1 to 2 hours; the ventilation system is faulty, check whether the fan is damaged, whether the rotation direction is correct, and whether the ventilation duct is blocked. The bearing is worn, and the rotor sweep causes the rotor core to rub against each other and make a metal knocking sound, which causes the core temperature to rise rapidly, the motor to smoke, and even the coil to burn out.

Working environment reasons:

The motor winding is damp or dust, oil, etc. are attached to the winding, resulting in reduced insulation. The motor insulation resistance should be measured, and the motor should be cleaned and dried. The ambient temperature is too high. When the ambient temperature exceeds 35°C, the air inlet temperature is high, which will cause the motor temperature to be too high. The working environment should be improved. For example, a shelter should be built for shade.

Note: If a fault occurs due to electrical reasons, an electrician with a professional qualification certificate should be asked to repair it. People who have only a superficial understanding should not blindly repair it to prevent personal injury accidents.

• If the pump motor is found to be overheating, the following solutions can be taken

First, look at the difference between the current of the water pump at this time and the current during normal operation. If it is smaller than the normal operation (the base is 23 of the normal current), then there are problems such as impeller wear and blockage of the check valve on the top of the pump head. If the current is as large as usual, there are problems such as pipe gasket leakage, water pipe leakage, and water pump leakage. If the current is larger than the normal operation, then the base can be determined to be a problem with the wear parts. In addition, if the cable is damaged, although the water output is the same as usual, the current will be larger. The current of a three-phase 380V motor is generally 2.2A. The above reasons can be found out by finding a maintenance personnel who regularly maintains the water pump.

Cavitation phenomenon, pump cavitation is caused by the vaporization of water. The so-called vaporization is the process of water changing from liquid to gas. The vaporization of water has a certain relationship with temperature and pressure. Under a certain pressure, when the temperature rises to a certain value, the water begins to vaporize; if the pressure is reduced to a certain value at a certain temperature, the water will also vaporize. This pressure is called the vaporization pressure of water at that temperature. If the pressure in a certain local area is equal to or lower than the evaporation pressure corresponding to the water temperature during the flow process, the water will vaporize in that area.
After vaporization occurs, many small bubbles of steam and gas will be formed. When the bubbles flow from the low-pressure area to the high-pressure area with the water flow, the bubbles burst under the action of high pressure, and the high-pressure water flows to the space occupied by the original bubbles at a very high speed, forming an impact force. Under the action of water hammer pressure, the metal surface forms fatigue and is severely damaged. Therefore, the process of bubble formation, development and rupture leading to material destruction is called cavitation.