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How To Save Energy On Motors Without Replacing Them?

The energy saving of the motor is mainly realized through the six plans including the selection of an energy-saving motor, the appropriate selection of the motor capacity, the use of magnetic slot wedges instead of the original slot wedges, the use of Y/△ automatic conversion devices, power factor reactive power compensation of motors, and liquid speed regulation of winding motors.

How To Save Energy On Motors Without Replacing Them?插图

Energy consumption is mainly manifested in the following aspects:

1. The load rate of the motor is low.

Due to improper selection of the motor, excessive margin, or changes in the production process, the actual working load of the motor is far less than the rated load, and the motor accounting for 30% to 40% of the installed capacity operates at a rated load of 30% to 50%. Operating efficiency is too low.

2. The power supply voltage is asymmetrical or too low.

Due to the unbalanced single-phase load of the three-phase four-wire low-voltage power supply system, the three-phase voltage of the motor is asymmetrical, and the motor produces negative sequence torque, which increases the three-phase voltage asymmetry of the motor, and the motor produces negative sequence torque. Losses during operation of large motors. In addition, the grid voltage has been low for a long time, which makes the motor current in normal operation too large, so the loss increases. The greater the asymmetry of the three-phase voltage, the lower the voltage, and the greater the loss.

3. The old and old (eliminated) motors are still in use.

These motors use Class E insulation, are bulky, have poor starting performance, and have low efficiency. Although it has undergone years of renovation, it is still in use in many places.

4. Poor maintenance management.

Some units did not maintain the motors and equipment as required, and let them run for a long time, which caused the loss to increase continuously.

Therefore, in view of these energy consumption performances, it is worth studying which energy-saving scheme to choose.

How To Save Energy On Motors Without Replacing Them?插图1


Energy-saving electric and high-efficiency motors are used. Compared with ordinary motors, the overall design is optimized, and high-quality copper windings and silicon steel sheets are selected to reduce various losses. Losses are reduced by 20% to 30%, and efficiency is increased by 2% to 7%. ; The payback period is generally 1 to 2 years, some months. In comparison, high-efficiency motors are 0.413% more efficient than older motors. Therefore, it is imperative to replace the old motors with high-efficiency motors.


Properly select the motor capacity to achieve energy saving. The country has made the following regulations on the three operating areas of three-phase asynchronous motors: the economic operating area is between 70% and 100% of the load rate; the general operating area is between 40% and 70% of the load rate; The load rate below 40% is the non-economic operating area. Improper selection of motor capacity will undoubtedly cause a waste of electric energy. Therefore, using a suitable motor to increase the power factor and load rate can reduce power loss and save energy.


The magnetic slot wedge is used to replace the original slot wedge. The magnetic slot wedge mainly reduces the no-load iron loss in the asynchronous motor. The no-load additional iron loss is generated in the stator and rotor core by the harmonic flux caused by the cogging effect in the motor. The high-frequency additional iron loss induced by the stator and rotor in the iron core is called pulse vibration loss. In addition, the teeth of the stator and rotor are sometimes aligned and sometimes staggered, and the magnetic flux of the tooth clusters on the tooth surface changes, which can induce eddy currents in the tooth surface line layer, resulting in the surface loss.

Pulse vibration loss and surface loss are collectively called high-frequency additional loss, which account for 70% to 90% of the stray loss of the motor, and the other 10% to 30% are called load additional loss, which is produced by leakage flux. Although the use of magnetic slot wedges will reduce the starting torque by 10% to 20%, the iron loss of the motor using magnetic slot wedges can be reduced by 60k compared with the motor using ordinary slot wedges, and it is very suitable for motor transformation with no-load or light-load starting.


Y/△ automatic switching device is used to solve the waste of electric energy when the equipment is lightly loaded. On the premise of not replacing the motor, the Y/△ automatic switching device can be used to achieve the purpose of saving electricity. Because in the three-phase AC grid, the voltage obtained by different connection methods of the load is different, the energy absorbed from the grid is also different.


The main purpose of reactive power compensation is to improve the power factor and reduce power loss. The power factor is equal to the ratio of active power to apparent power. Generally, a low power factor will cause an excessive current. For a given load, when the supply voltage is constant, the lower the power factor, the greater the current. Therefore, the power factor should be as high as possible to save electric energy.


Wound motor liquid speed regulation. The liquid resistance speed control technology is developed on the basis of the traditional product liquid resistance starter. The purpose of step-less speed regulation is still achieved by changing the distance between the plates and adjusting the size of the resistor. This makes it have a good starting performance at the same time. It has a problem with heating and the temperature rises when it is powered on for a long time. Due to the unique structure and reasonable heat exchange system, its working temperature is limited to a reasonable temperature.

The liquid resistance speed control technology for winding motors has been rapidly promoted due to its advantages of reliable operation, convenient installation, large energy saving, easy maintenance, and low investment. For some speed control accuracy requirements are not high, and the speed control range is not wide. , and the winding motors with infrequent speed regulation, such as large and medium-sized winding asynchronous motors for fans, water pumps, and other equipment, have a remarkable effect on liquid speed regulation.

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