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Pump is working well, why motor is very hot?

Views: 17     Author: Site Editor     Publish Time: 06-29-2021      Origin: Site


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“The pump is in good condition, and the motor is hot." Some people some times happed this problem. Today, HOFFWELL PUMP has sorted out the relevant reasons for this problem.


  1. Caused by motor phase missing operation;

    The lack of phase often causes the motor can not run, or the speed is slow after starting, or the rotation is powerless, the current increases, and there is a "buzzing" sound happen. If the load on the shaft does not change, the motor will be in a serious overload state, and the stator current will reach 2 times of the rated value or even higher. In a short time, the motor will heat up or even burn down

2. Abnormal vibration or noise is easy to cause motor hot;

If pump working well,  the vibration may caused by the motor itself. Most of the vibration is caused by the bad dynamic balance of the rotor, the bad bearing, the bending of the shaft, the different shaft axes of the end cover, the base and the rotor, the looseness of the fasteners or the uneven foundation of the motor installation. It can also be caused by the mechanical end transmission, which should be eliminated according to the specific situation.

3. The small air gap between the stator and rotor of the motor;

In medium and small type motors, the air gap is generally 0.2mm ~ 1.5mm. When the air gap is large, the excitation current is required to be large, which affects the power factor of the motor; If the air gap is too small, the rotor may have friction or collision. Generally, due to the serious bearing out of tolerance and the wear and deformation of the inner hole of the end cover, the different axes of the frame, the end cover and the rotor cause the bore sweeping, and it is easy to make the motor heat up or even burn down. If it is found that the bearing is worn, it should be replaced in time, and the end cover should be replaced or brush plated. The simpler method is to insert the end cover.

4. The bearing does not work well, causing the motor hot;

The bearing end can be detected by hand or thermometer to judge whether the temperature is within the normal range; If you hear the impact sound, it means that one or several balls may be crushed. If you hear the hissing sound, it means that the bearing oil is insufficient. The motor should change the grease once in 3000-5000 hours.

5. If the power supply voltage is too high and the excitation current increases, the motor will overheat;

Too high voltage will endanger the insulation of the motor, so that it has the risk of breakdown. When the power supply voltage is too low, the electromagnetic torque will be reduced. If the load torque is not reduced and the rotor speed is too low, the increase of slip will cause the motor overload and heating, and the long-term overload will affect the life of the motor. When the three-phase voltage is asymmetric, that is, when the voltage of one phase is too high or too low, the current of one phase will be too large and the motor will heat up.

6. The leakage of materials into the motor reduces the insulation of the motor and make the motor hot;

When solid materials or dust enter into the motor from the junction box, it will reach the air gap between the stator and rotor of the motor, causing the motor to sweep the bore until the insulation of the motor winding is worn out, causing the motor to be damaged or scrapped.

7. Other reasons: 

If the ambient temperature is high, the motor lacks a fan, the fan is incomplete or the fan cover is missing.

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