Motor is an indispensable power source equipment in manufacturing industry. Why does the motor burn out? What causes it? Investigate its reason, you can find, in the production process, there are many kinds of circumstances, may cause motor burn out!
To find the cause, we can start with the source of the failure.
First, you need to figure out, is the motor burnt out bearing or coil? If the bearing is burned, that is a mechanical fault, the motor hardware quality is not good; If the coil burned, it was an electrical fault. Generally, it is caused by over current. Sometimes, the voltage is unstable, too high or too low, which leads to coil heating, short circuit and burn out the motor. To rule this out, check that the operating voltage is not too far from the rated voltage. If yes, that is the voltage instability caused by the fault; If not, the current is unstable.
The current of the motor appears short circuit, generally can be divided into four situations:
1. The equipment runs over load and over current for a long time. Daily, the starting current of the motor is 3-5 times of the rated current, so it is necessary to avoid the situation that the equipment is started with load or full load.
2. The working environment of the motor is humid.
3. Mechanical failure of the pump leads to over-load of the motor, which causes excessive current and burns out the coil.
4. There are problems in heat dissipation of the motor.
Two common fault analysis: missing phase, overload
Reason: it is generally caused by the missing phase of power supply (one phase is not supplied or the supply voltage is insufficient) or the contact point of the contactor in the circuit is not closed, resulting in the connection point disconnection, loosening or oxidation of the contact position.
Features: one or two phases (Grade 4) in the winding are all blackened, the coil is damaged symmetrically, there are rules. (PS: the electric machine of triangle connection will burn out the one-phase winding, and the electric machine of star Y connection will burn out the two-phase winding)
So, if the motor is burned because of the lack of phase, then there will be winding not burned; If the motor burns up because of the heavy load, all the three-phase winding will break the insulation to the ground.
Reason: it is generally caused by the electrical long time over-current operation, overheating operation, frequent start or brake, wiring error.
Features: winding all become black, end of the ribbon discoloration and become brittle or even broken.
Therefore, motor fault can be divided into two categories: mechanical fault and electrical fault. If the motor burn out is only a mechanical failure, then directly change the motor supplier; If it is an electrical fault, the best way is to install a motor protector in advance, to prevent protection, to avoid the next occurrence.
Post time: Nov-01-2019