Cause analysis and solution for oil pump motor heating and burning motor

In actual production, due to electrical or mechanical reasons, the oil pump motor often causes overheating or burnout. Therefore, it is especially important to check the temperature of the motor during operation and to determine its fault. There are roughly the following reasons and solutions for motor heating. Dalan Motor's small series is proposed for your reference.

1. The air gap between the stator and the rotor is very small, which easily leads to the collision between the stator and the rotor. In medium and small 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 be rubbed or collided. Generally, due to the serious tolerance of the bearing and the wear and deformation of the inner hole of the end cover, the bottom of the base, the end cover and the rotor cause the broom, which is easy to cause the motor to heat or even burn.

2. The abnormal vibration or noise of the motor is likely to cause the heat of the motor. This situation is caused by the vibration caused by the motor itself. Most of them are due to poor rotor dynamic balance, poor bearing, bending of the shaft, different ends of the end cover, the base and the rotor. The heart, the loose fasteners or the grounding of the motor installation are not flat, the installation is not in place, or it may be transmitted from the mechanical end, and should be excluded according to the specific situation.

3. The bearing work is not normal, it must be caused by the normal operation of the oil pump motor heating bearing can be judged by hearing and temperature experience. The bearing end can be detected by hand or thermometer to determine whether the temperature is within the normal range; the bearing rod (copper rod) can also be used to contact the bearing box. If the impact sound is heard, it means that there may be one or several balls crushed, if heard The buzzing sound is that the bearing has insufficient lubricating oil, and the motor should be replaced with grease for about 3,000 hours to 5,000 hours.

4. The power supply voltage is high, the excitation current is increased, and the motor will be excessively heated. Excessive voltage may endanger the insulation of the motor and cause it to be broken down. When the power supply voltage is too low, the electromagnetic torque will be greatly reduced. If the load torque is not reduced, the rotor rotation number is too low. At this time, the increase of the slip rate will cause the motor to be overloaded and generate heat, and the long-term overload will affect the life of the motor. When the three-phase voltage is asymmetrical, that is, when the voltage of one phase is high or low, it will cause the current of a certain phase to be too large, the motor will heat up, and at the same time, the torque will be “beep” when the torque is reduced, and the winding will be damaged if the time is long. In short, whether the voltage is too high, too low, or the asymmetry of the three-phase voltage will increase the current, and the motor will heat up and damage the motor. Therefore, according to national standards, the motor power supply voltage should not change by more than ±5% of the rated value, and the motor output power can be maintained at the rated value. The motor supply voltage must not exceed ±10% of the rated value. The difference between the three-phase supply voltage should not exceed ±5% of the rated value.

5. Winding short circuit, turn-to-turn short circuit, phase-to-phase short circuit and winding open circuit, after the insulation between two adjacent wires in the winding is damaged, the two conductors collide, which is called winding short circuit. A short circuit in a winding that occurs in the same winding is called a turn-to-turn short circuit. A winding short circuit occurring between two phase windings is called an interphase short circuit. Either way, it will increase the current of one phase or two phases, causing local heating, causing insulation aging to damage the motor. Winding open circuit is a fault caused by the stator or rotor winding of the motor being broken or blown. Whether the winding is short-circuited or open circuit may cause the motor to heat up or even burn out. Therefore, this situation must be stopped immediately after this happens.

6. Material leakage enters the inside of the motor, so that the insulation of the motor is reduced, so that the allowable temperature rise of the motor is reduced. When solid materials or dust enter the motor from the junction box, it will reach between the air gap of the stator and rotor of the motor, causing the motor. Broom until the motor winding insulation is worn out, causing the motor to be damaged or scrapped. If liquid and gaseous media leak into the motor, it will directly cause the motor insulation to drop and trip. Generally, liquid and gas leaks have the following manifestations: (1) leakage of various containers and conveying pipes, leakage of pump seals, flushing equipment and the ground.

7. Almost half of the motor burns out due to the lack of phase caused by the motor phase loss operation, which often causes the motor to fail to run or the speed is slow after starting, or the rotating forceless current increases the "click" sound. If the load on the shaft does not change, the motor is in a severe overload state and the stator current will reach 2 times or higher of the rated value. The motor will heat up or burn out in a short time.

8. Other non-mechanical electrical fault causes: The motor temperature rise caused by other non-mechanical electrical faults may cause motor failure in severe cases. If the ambient temperature is high, the motor lacks a fan, the fan is incomplete, or the fan cover is missing. In this case, cooling must be forced to ensure ventilation or replacement of blades, otherwise the normal operation of the motor cannot be guaranteed.







----- Editor-in-Chief: Dalan Oil Pump Motor 02-Procurement Consultant

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