High and low voltage of three-phase asynchronous motor

High and low voltage of three-phase asynchronous motor

Three phase asynchronous motors have high requirements for the stability of power supply voltage. High or low voltage can have a significant impact on the operation of the motor, as shown below:

1、 The impact of low voltage

Difficulty in starting

When the voltage is too low, the rotating magnetic field generated by the stator winding weakens, resulting in insufficient electromagnetic torque, making it difficult for the motor to overcome static friction and start.

The impact is relatively small under light load, but the current will increase significantly under heavy load, which may cause overheating or burning.

Risk of overheating and damage

The impact is limited under light load, but prolonged low voltage operation can lead to a continuous increase in stator current and intensified power loss.

When overloaded, due to insufficient torque, the current increases more significantly, which can easily exceed the insulation capacity of the winding and cause short circuits or burns.

Other issues

Frequent voltage fluctuations may cause motor vibration, increased noise, and even damage to bearings and seals.

2、 The impact of high voltage

Overheating and insulation damage

Excessive voltage can cause an increase in stator winding current and a rapid rise in winding temperature, exceeding the tolerance limit of the insulation material, which may lead to insulation breakdown or burnout.

Long term overheating can accelerate insulation aging and shorten the lifespan of electric motors.

mechanical damage

Excessive current may cause winding deformation or mechanical stress, leading to rotor eccentricity, increased vibration, and even damage to couplings or bearings.

Other risks

High voltage may cause arc discharge, damaging the motor casing or surrounding equipment.

3、 National standards and maintenance recommendations

Voltage fluctuation range: According to national standards, electric motors are allowed to have voltage fluctuations within ± 5% of the rated value. If the range is exceeded, the power grid or circuit needs to be adjusted.

Daily maintenance:

Regularly measure voltage, promptly correct line voltage drop or replace wires.

Load matching: To avoid long-term overload operation, it is recommended to adjust the power capacity according to the load.

Heat dissipation guarantee: Ensure good ventilation, clean heat sinks, and avoid high ambient temperatures.

By reasonably controlling voltage fluctuations and strengthening maintenance, the service life of three-phase asynchronous motors can be effectively extended and their stable operation can be guaranteed.