Do You Know Why The Motor Burn Out?

Why does the motor of centrifugal pump burn out? Motor as one of the most commonly used moving equipment, what is the reason of burning phenomenon? Let us talk with it today.

First of all, make sure whether the motor of centrifugal pump burns the bearing (mechanical failure) or the coil (electrical failure)?

centrifugal pump

There are several reasons for the current short circuit:


1. Equipment overload operation.


Make the motor of centrifugal pump run at rated current or over rated current for a long time, especially note that the starting current of the motor is 3-5 times of the rated current, so try to avoid running with load or full load when starting the equipment (mainly depends on the matching margin of the rated current and normal running current of the motor)


2. The motor works in a humid working environment.


Before starting the motor of centrifugal pump, the insulation to ground and phase to phase of the coil shall be checked. The requirements for insulation of different voltage levels are also different, which can be checked with reference to relevant national standards. During the operation of the motor, attention should be paid to the waterproof and moisture-proof of the motor.


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


4. There is a problem with the heat dissipation of the motor of centrifugal pump.

Generally, the motor coil is air-cooled, and the submersible pump is water-cooled. Air air heat exchanger and air water heat exchanger are used to cool large motors. If the cooling water (air) is cut off and the coil cannot be cooled, the coil may be burnt.

motor of centrifugal pump

The actual use head is too much lower than centrifugal pump nameplate head:

The head of centrifugal pump is used to overcome the height and resistance. When the high head pump works at the high head point, its flow is the flow at the design point. If it works at the low head, it is equivalent to the reduction of the outlet resistance of the pump. At this time, the flow of centrifugal pump will increase, the motor will be overloaded, and the motor will burn to a certain extent.


For example, the head of a feed of centrifugal pump is 50m, and the flow is 50m3 / h. when it feeds water to 50m, its flow is 50m3 / h. when it feeds water to 40m, its height and resistance reduce its flow to 80-90m3 / h or more, and then the motor will heat or burn.


The reason summary of motor burning can be divided into: load, power supply, motor insulation, lack of equality.

1. It is generally caused by the lack of phase in the power supply (one phase is not supplied or the supply voltage is insufficient) or the contact point of the contactor in the line is not closed, the connection point of the conductor is open, loose or the contact position is oxidized.


1. The motor of centrifugal pump is connected in a triangle way: only one phase winding will be burned, and the insulation damage of one phase winding to the ground can be measured with a megger (megger).


2. The motor is connected in a star (y) way: if there are two-phase windings that will burn off, the megger (megger) can be used to measure the insulation damage of the two-phase winding to the ground.

Overload: cause:


Generally, it is caused by over-current operation for a long time, overheated operation, frequent start-up or braking, and wrong wiring (delta connection into star connection). The overheated reason is: over load operation, resulting in motor heating. Or the motor starts frequently, causing the motor to overheat.

features:


The winding is all black, the end tie is discolored, brittle or even broken.


In this case, both ends of the stator and rotor in the motor of centrifugal pump will be blackened, and the blackened part is relatively uniform (generally, the motor has a specific operating power, which is called rated power, and the unit is watt (W). If the actual operating power of the motor exceeds the rated power of the motor of centrifugal pump in some cases, it is called motor overload).

3. Turn to turn

reason:


The enameled wire is broken during the manufacturing process of the motor.


features:

The winding is partially burnt out. Usually, the inner cavity of the motor is clean, with only one explosion point.

centrifugal pump motor