Why does the centrifugal pump appear to burn the motor?

First of all, first figure out whether the motor burned the bearing or burned the coil?

If it is a fault of the burning coil, it is mainly caused by overcurrent. Sometimes the voltage is too high or too low, which will cause the coil to be short-circuited. Therefore, check whether the voltage during operation is too much difference from the rated voltage.

The motor is shorted for several reasons:

1. The equipment is overloaded, so that the motor runs at rated current or over rated current for a long time. It is important to note that the starting current of the motor is 3-5 times of the rated current, so it should be avoided to start the equipment with load or full load (mainly depends on the matching current of the motor and the normal running current)

2. The motor works in a damp working environment. Before the motor is started, the ground insulation and phase insulation of the coil should be checked. The insulation requirements for different voltage levels are different. You can check it according to the relevant national standards. During the operation of the motor, attention should be paid to the waterproof and moistureproof of the motor.

3. The mechanical failure of the pump causes the motor to be overloaded, and the current is too large to burn the coil.

4. The heat dissipation of the motor is a problem. Generally, the motor coils are air-cooled and the submersible pump is a water-cooled casing. Large motors are mostly cooled by air-to-air heat exchangers and air-to-water heat exchangers. If the cooling water (air) is broken and the coil cannot be dissipated, the coil may be burnt.

5. The actual use of the lift is less than the pump nameplate lift:

The lift of the centrifugal pump is used to overcome the height and resistance. When the high lift pump is working at the high lift point, its flow is the flow at the design point. If it is working at low lift, it is equivalent to the outlet resistance of the pump is reduced. The flow rate of the centrifugal pump will increase and the motor will be overloaded. If it exceeds a certain level, the motor will be burnt.

Burner type diagram

The reasons for the motor burning can be divided into: load, power supply, motor insulation, and lack of equal.

01 lack of phase

the reason:

Generally, the power supply is out of phase (one phase is not supplied or the power supply voltage is insufficient) or the contact point of the contactor in the line is not closed, the wire connection point is disconnected, loose or contact position oxidation occurs.

1. The motor is connected in a delta connection: only one phase winding will be burned, and the insulation failure of the one-phase winding to the ground can be measured with a megger (shake table).

2. The motor is star-shaped (Y) connection: two-phase windings will burn out, and the two-phase windings can be measured for damage to the ground by a megger (shaker).


One or two phases (four stages) in the winding are all blackened, the coils are damaged symmetrically, and there are rules for phase loss. In short: If the motor burns out due to lack of phase, then the winding will not be burned. If the motor burns due to excessive load, the three-phase winding will be completely damaged by ground insulation.

02 overload

the reason:

Generally, the motor runs for a long time without overcurrent, overheating, frequent starting or braking, and wiring errors also cause (triangulation is connected to the star). The cause of overheating is: Exceeding the load operation, causing the motor to heat up. Or the motor starts frequently, causing the motor to overheat.


The windings all turn black and the end ties are discolored and become brittle or even broken.

This kind of burning opportunity appears that both ends of the motor’s internal stator and rotor will burn black, and the blackened parts are relatively uniform (generally, the motor has a certain operating power, called rated power, in watts (W), if at some In this case, the actual use power of the motor exceeds the rated power of the motor, so this phenomenon is called motor overload).

03 Daytime

the reason:

The enameled wire caused by the motor manufacturing process is broken.


The winding is partially blown. Usually, when the motor cavity is clean, there is only one explosion point.

04 phase

the reason:

The phase paper is not in place, or the phase paper (casing) is broken.


The two phases of the motor burned out adjacent to each other.

05 Ground Strike

the reason:

There is not enough distance between the coil and the end cap base.


There are black marks between the coil and the end cap or end cap.

Please select a matching motor for your centrifugal pump.

Please contact us with any questions.