Seven energy saving solutions for motors

15/06/2019

The performance of motor energy consumption is mainly in the following aspects:
First, the motor load rate is low. Due to improper motor selection, excessive margin or changes in production process, the actual working load of the motor is much smaller than the rated load. The motor that accounts for 30%~40% of the installed capacity runs at 30%~50% of the rated load. The efficiency is too low.

Second, the power supply voltage is asymmetrical or the voltage is 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, the motor generates negative sequence torque, and the three-phase voltage of the motor is asymmetrical, and the motor generates negative sequence torque. Loss in the operation of large motors. In addition, the grid voltage is low for a long time, so that the motor current of normal operation is too large, so the loss increases, the greater the asymmetry of the three-phase voltage, and the lower the voltage, the greater the loss.

Third, the old and old (eliminated) motors are still in use. These motors use Class E insulation, which is bulky, has poor starting performance and low efficiency. Although it has undergone an annual transformation, there are still many places in use.

Fourth, the maintenance management is not good. Some units do not perform maintenance on the motor and equipment as required, and allow them to operate for a long period of time, resulting in increasing losses.
Therefore, for these energy-consuming performances, it is worthwhile to study which energy-saving schemes to choose.

There are roughly seven types of motor energy saving solutions. Experts analyzed one by one and chose energy-saving motors. Compared with ordinary motors, high-efficiency motors optimize the overall design, using high-quality copper windings and silicon steel sheets, reducing various losses, reducing losses by 20% to 30%, and improving efficiency by 2% to 7%. Usually 1 to 2 years, some months. In comparison, the efficiency of the high-efficiency motor is 0.413% higher than that of the J02 series motor. Therefore, it is imperative to replace the old motor with a high-efficiency motor.

Properly select the motor capacity to achieve energy savings. The state has specified the following three operating areas for three-phase asynchronous motors: the load rate is between 70% and 100% for the economic operation area; the load rate is between 40% and 70% for the general operating area; the load rate is 40%. The following are non-economic operating areas. Improper selection of motor capacity will undoubtedly result in waste of electrical energy. Therefore, using a suitable motor to improve the power factor and load rate can reduce power loss and save power.

The magnetic slot wedge is used instead of 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 the pulse vibration loss. Further, the stator and the rotor tooth portions are sometimes aligned and sometimes shifted, and the tooth surface tooth cluster magnetic flux is fluctuated, and eddy current can be induced in the tooth surface line layer to cause surface loss. Pulse vibration loss and surface loss are called high frequency additional loss, which account for 70%~90% of motor stray loss. The other 10%~30% is called load additional loss, which is generated by leakage flux. Although the use of magnetic wedges will reduce the starting torque by 10% to 20%, the motor with magnetic wedge can reduce the iron loss by 60k compared with the motor with ordinary slot wedge, and it is suitable for motor modification of no-load or light-load starting. .

Y/△ automatic conversion device is adopted. In order to solve the problem of waste of electric energy when the device is lightly loaded, the Y/△ automatic conversion device can be used to achieve the purpose of saving electricity without replacing the motor. Because the voltages obtained by different connections of the three-phase AC grid are different, the energy drawn from the grid is different.

The power factor of the motor is reactively compensated. Increasing the power factor and reducing the power loss are the main purposes of reactive power compensation. The power factor is equal to the ratio of active power to apparent power. Usually, the power factor is low, which will cause the current to be too large. For a given load, when the supply voltage is constant, the lower the power factor, the larger the current. Therefore, the power factor is as high as possible to save power.

Frequency. Most fan and pump loads are selected according to the full load demand, and most of the time in actual application is not at full load. Because the AC motor speed regulation is very difficult, the wind deflector, the return valve or the opening and closing time are often used to adjust the air volume or flow rate. At the same time, it is difficult for the large motor to frequently start and stop under the power frequency state, and the power impact is large, which will inevitably cause power loss and Current shock when starting the shutdown. Direct control of fan and pump load by frequency converter is the most scientific control method. When the motor is running at 80% of rated speed, the energy saving efficiency is close to 40%. At the same time, closed loop constant voltage control can be realized, and energy saving efficiency will be further improved. . Because the frequency converter can realize the soft stop and soft start of the large motor, the voltage shock during startup is avoided, the motor failure rate is reduced, the service life is prolonged, and the capacity requirement and reactive power loss of the power grid are also reduced.

Winding motor liquid speed control. The liquid resistance speed control technology is developed on the basis of the traditional product liquid resistance starter. Still achieve the purpose of stepless speed regulation by changing the size of the plate spacing adjustment resistor. This makes it have good starting performance at the same time, it is energized for a long time, which brings about heating and heating problems. Due to the unique structure and reasonable heat exchange system, the working temperature is limited to a reasonable temperature. The liquid resistance speed control technology for winding motor is quickly promoted due to its reliable operation, convenient installation, large energy saving, easy maintenance and low investment. It is not required for some speed regulation accuracy, and the speed regulation range is not wide. Winding type motors with infrequently adjustable speeds, such as large and medium-sized wound-type asynchronous motors such as fans and pumps, have significant liquid speed control effects.
Energy saving and environmental protection, smart life. Will be an important direction of human development in the future!