Ren Yi official website updated on July 9

 

The energy consumption of the motor is mainly in the following aspects:

 

One is the low motor load rate. Due to improper motor selection, excessive surplus or production process changes, the actual working load of the motor is much smaller than the rated load. The motor, which accounts for about 30% to 40% of the installed capacity, runs under 30% to 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 unbalance of the single-phase load of the three-phase four-wire low-voltage power supply system, the three-phase voltage of the motor is asymmetry, and the motor generates negative sequence torque, which increases the asymmetry of the three-phase voltage of the motor, and the motor generates negative sequence torque. Losses in operation of large motors. In addition, the long-term low voltage of the power grid makes the normal working motor current too large, and thus the loss increases. The greater the asymmetry of the three-phase voltage and the lower the voltage, the greater the loss.

 

The third is that old and old (obsolete) motors are still in use. These motors use Class E insulation, are large in size, have poor starting performance and low efficiency. Although it has undergone years of renovation, it is still in use in many places.

 

Fourth, poor maintenance management. Some units did not maintain the motors and equipment in accordance with the requirements and left them in long-term operation, resulting in increasing losses.

 

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

 

1. Use energy-saving motors

 

Compared with ordinary motors, the high-efficiency motor optimizes the overall design, selects high-quality copper windings and silicon steel sheets, reduces various losses, reduces losses by 20% to 30%, and increases efficiency by 2% to 7%; investment payback period Generally it is 1 to 2 years, some months. In comparison, the efficiency of high-efficiency motors is 0.413% higher than that of J02 series motors. Therefore, it is imperative to replace old-style motors with high-efficiency motors.

 

2. Appropriate selection of motor capacity to achieve energy saving

 

The state has made the following regulations for the three operating areas of three-phase asynchronous motors: load rates between 70% and 100% are economic operating areas; load rates between 40% and 70% are general operating areas; load rates are 40% The following are non-economic operating areas. Improper selection of motor capacity will undoubtedly cause a waste of electrical energy. Therefore, using a suitable motor to improve the power factor and load rate can reduce power loss and save energy.

 

3. Use magnetic slot wedge instead of original slot wedge

 

Magnetic slot wedges mainly reduce the no-load iron loss in asynchronous motors. No-load additional iron losses are generated in the stator and rotor cores due to 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 pulsation loss. In addition, the stator and rotor teeth are sometimes aligned and sometimes staggered, and the magnetic flux of the tooth clusters fluctuates, which can induce eddy currents in the tooth surface line layer and cause surface loss. The pulsation loss and the surface loss are collectively called the high-frequency additional loss, they account for 70% to 90% of the motor's stray loss, and the other 10% to 30% is called the load additional loss, which is generated by the leakage flux. Although the use of magnetic slot wedge will reduce the starting torque by 10%~20%, the iron loss of the motor with magnetic slot wedge can be reduced by 60k compared with the motor with ordinary slot wedge, and it is very suitable for the motor transformation of no-load or light-load start. .

 

4. Adopt Y/△ automatic conversion device

 

In order to solve the waste of electric energy when the equipment is lightly loaded, the Y/△ automatic conversion device can be used to save electricity without replacing the motor. Because in the three-phase AC power grid, the voltage obtained by the different connections of the load is different, so the energy drawn from the power grid is also different.

 

5. Power factor and reactive power compensation of the motor

 

Improving power factor and reducing power loss are the main purposes of reactive power compensation. Power factor is equal to the ratio of active power to apparent power. Generally, low power factor will cause 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 is as high as possible to save energy.

 

6. Frequency conversion speed regulation

 

Most fan and water pump loads are selected based on the amount required for full-load work. In actual applications, most of the time is not in a full-load working state. Because AC motors are difficult to adjust speed, windshields, return valves or open and stop time are often used to adjust air volume or flow. At the same time, it is difficult for large motors to frequently start and stop under power frequency conditions. The power impact is relatively large, which will inevitably cause power loss and Current impact when starting and stopping. Using a frequency converter to directly control fans and pump loads is the most scientific control method. When the motor runs at 80% of the rated speed, the energy-saving efficiency is close to 40%. At the same time, closed-loop constant pressure control can be realized, and the energy-saving efficiency will be further improved. . Because the frequency converter can realize the soft stop and soft start of the large motor, it avoids the voltage shock when starting, reduces the motor failure rate, extends the service life, and also reduces the capacity requirement and reactive power loss of the power grid.

 

7. Winding motor liquid speed regulation

 

The liquid resistance speed regulation technology is developed on the basis of the traditional product liquid resistance starter. The purpose of stepless speed regulation is still achieved by changing the distance between the plates and adjusting the size of the resistance. This makes it have good starting performance at the same time. It has been energized for a long time, which brings about the problem of heating and heating. Due to the unique structure and reasonable heat exchange system, its working temperature is limited to a reasonable temperature. The liquid resistance speed regulation technology for winding motors has been quickly promoted due to its reliable work, convenient installation, large energy saving, easy maintenance and low investment. It has low requirements for some speed regulation accuracy and wide speed regulation range. , And infrequent speed adjustment of winding motors, such as large and medium-sized winding asynchronous motors such as fans, water pumps and other equipment using liquid speed control effect is significant.

 

Sichuan Renyi Electric Co., Ltd. is registered under the name of Ren Yi, a senior technician for substation maintenance, and uses scientific research, knowledge innovation, publicity, promotion, and teaching that the temperature of electrical contacts (connectors) is lower than the temperature of its conductors (wires). The theory and technology of "thermal electrical contacts" produces and sells registered trademark electrical equipment that does not heat electrical contacts (joints), as a whole with patented products.