The operating voltage of the three-phase motor does not meet the rated voltage of the motor

Update:01 Apr 2021

Everyone knows that any kind of electrical appliance city has the requirement of rated voltage, and the same is true for the motor. In the actual operation process, if the motor runs within the range of normal turbulence, the motor will work normally, otherwise it will cause the motor to interfere.

The power supply frequency recovered in my country is 50Hz, and the frequency fault category is generally designated as ┬▒0.5Hz. If a three-phase asynchronous motor is used in the process, if the voltage is unusually high, its service life will be greatly shortened; if the voltage is unusually low, the power will be greatly reduced, which will seriously affect the working efficiency and the service life of the motor.

It can be seen that the operating voltage of the motor is related to the normal operation and service life of the motor equipment. Therefore, the continuous reliability of voltage, frequency and power supply is one of the basic indicators to guarantee the efficiency and life of the motor.

Three-phase asynchronous motor operating voltage is too low or too high will affect the motor as follows:

When the operating voltage of a three-phase asynchronous motor is too high (above 10%), the iron core magnetic circuit is saturated (because when the motor is designed and manufactured, the magnetic circuit under the rated voltage is generally around the saturation point), therefore, the main magnetic The increase of the flux makes the exciting current increase sharply (several times the increase of the applied voltage), so that the stator current increases, and the motor overheats, which may cause the temperature to rise beyond the allowable value and burn.

When the operating voltage of a three-phase asynchronous motor is too low (less than 5%), the motor torque will decrease in the square of the voltage. One will cause the starting torque to drop a lot, and the motor will start hard (slow or even unable to start); For a running motor, if the load is stable (heavy load or rated load operation), the rotor must maintain the necessary electromagnetic torque to balance the resistance torque of the load. This forces the rotor current to increase, which leads to an increase in the stator current, causing the motor to overheat, increase the temperature rise, shorten the life of the motor, and burn the motor.

Therefore, ensuring that the operating voltage of a three-phase asynchronous motor remains unchanged is a prerequisite for whether a motor can be used normally.

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