The motor current is too high, why does the motor have a serious heat problem?
When the motor current is high, it often shows that the motor is hot. The following 7 points basically summarize the reason why the motor current is too high. Let us learn.
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 corner of the blade is burned, causing 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). After confirming that there is no problem with the power supply, consider other factors.
1, motor overload operation
When the equipment is not matched and the load power of the motor is greater than the rated power of the motor, the long-term overload operation of the motor (ie, the small horse-drawn cart) will cause the motor to overheat. When repairing the overheated motor, first check whether the load power matches the motor power to prevent blind and unintentional disassembly.
2. The mechanical load of the drag is not working properly.
Although the equipment is matched, the mechanical load dragged is not working properly. When the load is large, the load is large and the motor is overloaded and generates heat.
3, the dragging machinery is faulty
When the machine being dragged is faulty, the rotation is inflexible or stuck, it will overload the motor and cause the motor winding to overheat. Therefore, when the motor is overheated, the load factor cannot be ignored.