Four common causes of overheating of pump motor
First, power supply reasons: high or low voltage, under a specific load, if the voltage change range should be in the rated value of +10% to -5% will cause motor overheating; The three-phase voltage of the power supply is asymmetrical, and the phase imbalance of the three-phase voltage of the power supply exceeds 5%, which will lead to overheating of the winding; The experience shows that more than 85% of the agricultural motor burned down is caused by the lack of phase operation, and it is necessary to install the lack of phase protection device.
Second, the reasons for the pump: the choice of power is not matched, the small horse cart, the electric overload operation for a long time, so that the motor temperature is too high; A motor that starts too frequently and has a short-time or intermittent duty system works continuously. The number of starts should be limited, the thermal protection should be correctly selected and used according to the rated rate on the motor.
Third, the reason for the electric body: the wrong connection, the △ shape is mistakenly connected to the Y shape, so that the temperature of the motor rapidly rises; The stator windings have inter-phase short circuit, inter-turn short circuit or local ground, the motor is partially overheated when light, and the insulation is burned out when serious. The squirrel cage rotor is broken or defective, the motor runs for 1 to 2 hours, and the iron core temperature rises rapidly; If the ventilation system is faulty, check whether the fan is damaged, whether the rotation direction is correct, and whether the ventilation channel is blocked. Bearing wear, rotor eccentric sweep makes the rotor core rub against each other to emit metal percussion sound, the core temperature rises rapidly, and the motor smokes and even the coil burns.
Fourth, the reason for the working environment: the motor winding is damp or dust, oil and other attached to the winding, 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 is high, which will make the temperature of the motor too high, and the working environment should be improved. Such as building a shelter for shade. Note: Due to electrical reasons for failure, should be asked to obtain professional qualification certificate of electrician maintenance, half-understood people can not blindly repair, to prevent the occurrence of personal injury accidents.
If the pump motor is found to be overheating, the following solutions can be taken
First of all, look at the current of the pump at this time and the current difference between normal operation. If it is smaller than normal operation (the base is 23 of the usual current), then there are problems such as impeller wear and blockage of the check valve at the top of the pump head. If the current is as large as the usual, it is the problem of leakage of pipe pad, pipe leakage, pump water leakage and so on. If the current is larger than that of normal operation, then the base can be determined to be the problem of wearing parts. In addition, if the cable is damaged, the water is the same as usual, but the current will be larger. The current of a 3-phase 380V motor is generally 2.2A. The above reasons can be found out as long as the repair personnel who often maintain the pump.
Cavitation phenomenon, the cavitation of the pump is caused by the vaporization of water, the so-called vaporization is the process of converting water from liquid to vapor state. The vaporization of water has a certain relationship with temperature and pressure, under a certain pressure, when the temperature rises to a certain value, water begins to vaporize; If at a certain temperature, the pressure is reduced to a certain value, water will also vaporize, and this pressure is called the vaporization pressure of water at this temperature. If during the flow process, the pressure in a local area is equal to or lower than the evaporation pressure corresponding to the water temperature, the water will vaporize there.
After vaporization occurs, many small bubbles of steam and gas are formed. When the bubble flows from the low pressure area to the high pressure area with the water flow, the bubble breaks under the action of high pressure, and the high pressure water flows to the space occupied by the original bubble at a very high speed, forming an impact force. Under the action of water hammer pressure, the metal surface formed fatigue and was seriously damaged. Therefore, the formation, development and rupture of the bubble resulting in the destruction of the material is called cavitation phenomenon.