1, the power supply voltage is too high When the power […]
1, the power supply voltage is too high
When the power supply voltage is too high, the motor back electromotive force, magnetic flux, and magnetic flux density increase. Since the magnitude of the iron loss is proportional to the square of the magnetic flux density, the iron loss increases, causing the core to overheat. The increase of the magnetic flux causes the excitation current component to increase sharply, which causes the copper loss of the stator winding to increase and the winding to overheat. Therefore, when the power supply voltage exceeds the rated voltage of the motor, the motor will overheat.
2, the power supply voltage is too low
When the power supply voltage is too low, if the electromagnetic torque of the motor remains unchanged, the magnetic flux will decrease, the rotor current will increase accordingly, and the load power component will increase in the stator current, causing the copper loss of the winding to increase, resulting in a stator and a rotor. The winding is overheated.
3, the power supply voltage is asymmetrical
When the power line is disconnected, the fuse is blown, or the burnt of the blade starter causes a phase failure, the three-phase motor will go single-phase, causing the running two-phase winding to overheat through a large current and burn it. Therefore, fuses are generally not protected for three-phase motors.
4, three-phase power imbalance
When the three-phase power supply is unbalanced, the three-phase current of the motor is unbalanced, causing the winding to overheat.
It can be seen from the above that when the motor overheats, the power supply should be considered first (soft start, inverter, servo drive can also be regarded as power supply). After confirming that there is no problem with the power supply, consider other factors.