There are several reasons for the overheating of the motor in terms of power supply:
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 will increase accordingly. Since the size 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 in magnetic flux also causes the component of the excitation current to increase sharply, resulting in increased copper loss in the stator winding and overheating of the winding. Therefore, when the power supply voltage exceeds the rated voltage of the motor, the motor will overheat.
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 correspondingly, and the load power component of the stator current will increase accordingly, causing the copper loss of the winding to increase. Cause the stator and rotor windings to overheat.
Asymmetric power supply voltage
When one phase of the power cord is broken, the fuse is blown in one phase, or the corner of the knife starting device is burned and one phase is blocked, it will cause the three-phase motor to go single-phase, causing the running two-phase winding to overheat through high current and even burn. Therefore, fuse protection is generally not suitable for three-phase motors.
Three-phase power unbalance
When the three-phase power supply is unbalanced, the three-phase current of the motor will be unbalanced, causing the winding to overheat. It can be seen from the above that when the motor is overheated, the power source should be considered first (soft start, frequency converter, servo drive can also be regarded as power source).
There are several reasons for the motor overheating in terms of load:
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 motor will be overloaded for a long time (ie a small horse-drawn cart), which will cause the motor to overheat. When repairing an overheated motor, you should first find out whether the load power is consistent with the motor power to prevent blind disassembly.
2. The dragged mechanical load is not working properly. Although the equipment is matched, the dragged mechanical load is not working properly. During operation, the load is large and sometimes small, and the motor is overloaded and heats up.
3. The dragging machinery is faulty. When the dragging machinery is faulty, rotating inflexibly or being 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.
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 will increase accordingly. Since the size 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 in magnetic flux also causes the component of the excitation current to increase sharply, resulting in increased copper loss in the stator winding and overheating of the winding. Therefore, when the power supply voltage exceeds the rated voltage of the motor, the motor will overheat.
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 correspondingly, and the load power component of the stator current will increase accordingly, causing the copper loss of the winding to increase. Cause the stator and rotor windings to overheat.
Asymmetric power supply voltage
When one phase of the power cord is broken, the fuse is blown in one phase, or the corner of the knife starting device is burned and one phase is blocked, it will cause the three-phase motor to go single-phase, causing the running two-phase winding to overheat through high current and even burn. Therefore, fuse protection is generally not suitable for three-phase motors.
Three-phase power unbalance
When the three-phase power supply is unbalanced, the three-phase current of the motor will be unbalanced, causing the winding to overheat. It can be seen from the above that when the motor is overheated, the power source should be considered first (soft start, frequency converter, servo drive can also be regarded as power source).
There are several reasons for the motor overheating in terms of load:
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 motor will be overloaded for a long time (ie a small horse-drawn cart), which will cause the motor to overheat. When repairing an overheated motor, you should first find out whether the load power is consistent with the motor power to prevent blind disassembly.
2. The dragged mechanical load is not working properly. Although the equipment is matched, the dragged mechanical load is not working properly. During operation, the load is large and sometimes small, and the motor is overloaded and heats up.
3. The dragging machinery is faulty. When the dragging machinery is faulty, rotating inflexibly or being 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.
コメント