Discussion on the Technical Measures of Power Saving in Motor Repair

1. Introduction

  Energy saving is an important problem facing the society today. For the motor repair department, it is also of far-reaching significance to study the power saving technology in the motor repair process. Generally speaking, reasonable use of AC motor must comply with the following points:

  A. The motor operates under high power factor and high efficiency;

  B. Ensure the service life of the motor, and ensure the reliability and safety of the motor during operation;

  C. During the use of the motor, ensure that the motor can save energy and electricity.

  In order to meet the requirements of energy saving and electricity saving in the process of motor repair, this paper studies several kinds of power saving technologies for motor repair.

2. Power saving process for motor repair

  a) Application of Magnetic Slot Wedge

  In the process of motor repair, ordinary bamboo wedge and epoxy plate wedge are generally used. However, the application of magnetic slot wedges is helpful to improve the power saving efficiency during motor repair. The repair practice has proved that when the magnetic slot wedge is applied to the open slot asynchronous high-voltage motor, the power saving effect of repair is particularly significant. The main reasons are as follows: the application of magnetic slot wedges helps to distribute the magnetic density of air gap more evenly, reduce the influence of tooth harmonic, surface loss and pulsation loss, and shorten the length of effective air gap at the same time; The use of magnetic slot wedges can improve the air gap magnetic potential waveform and motor power factor of the motor, help to reduce the no-load current of the motor, help to reduce the iron loss and temperature rise of the motor, and further extend the service life of the motor, and greatly reduce electromagnetic noise and vibration. The industrial practice shows that the application of magnetic slot wedges in motor repair can reduce the iron loss by 40% - 60%, increase the efficiency by 1% - 2%, and reduce the temperature by 10% - 20%. It is significant to improve the power factor, motor vibration and electromagnetic noise of the motor.

b) Application of far infrared technology

  Far infrared heating technology is a technology that heats objects by radiation. It is widely used. It was first used in the 1970s. In the process of motor repair, compared with other heating technologies, the application of far infrared heating technology to bake and heat the motor insulation has higher heating efficiency, which can greatly shorten the drying time. In addition, industrial practice has proved that the application of far infrared heating technology to bake and heat the motor can save 305kWh - 505kWh of electric energy compared with other heating methods, and can make the paint film adhere more firmly The quality of paint film is better. The reason why the heating electrical components can achieve such good results is that during the heating process, the coating surface of the electrical heating components has far-infrared rays. After these far-infrared rays are absorbed by the polymer compound inside the motor insulation material, the internal energy level of the polymer compound will change and the temperature will rise. Therefore, in the process of motor repair, the application of far infrared ray to the heating of components has the advantages of short drying time and high efficiency. At present, far infrared heating technology is quite mature, and far infrared heating tubes are also widely used. There are finished products available for purchase, or they can be sprayed by themselves.

c) Improve the insulation level of motor

  At present, in order to prolong the service life of the motor and save electricity, during the repair of small and medium-sized low-voltage motors, Class E insulation is often used to replace Class A insulation of old motors. However, nowadays, with the continuous development of relevant technologies of insulating materials, the technology level of insulating materials is also improving. It is an inevitable trend to replace Class E insulation with Class B insulation in the current motor repair process. It has been proved that the change of the insulation grade can not only improve the reliability of the motor during operation, but also help to extend the service life of the motor.

  During motor repair, since there is no need to make any changes to the QZ type electromagnetic wire and # 1032 insulating paint that are already Class B insulated, it is very simple to replace E-all insulation with Class B insulation, just change the material specification, slot wedge and slot insulation of NA outgoing wire. In engineering practice, the specific measures to change NA outgoing line, slot wedge and slot insulation are as follows: IB Q rubber cable is used as NA outgoing line; Level B slot wedges such as # 3240 epoxy sheet slot wedges or insulated MDB soft slot wedges are used to replace the original level E slot wedges; The groove insulation is replaced by a new type of composite fiber paper composed of polyester film and polyurethane fiber.

d) Application of adhesive

  The use of adhesives in the motor repair process can shorten the motor repair cycle, reduce the motor repair cost, and help improve the power saving performance in the motor repair process. For example, when the mating surfaces of the inner and outer rings of rolling bearings were worn, they were often first treated by spraying, copper pad, insert sleeve and other processes, and then repaired by surface "roughening". Although these treatment methods can achieve the desired effect, they are inconvenient to operate, expensive and time-consuming. However, the use of agricultural machinery # 2 adhesive can effectively avoid the above shortcomings. It can be seen from the repair practice that the # 2 adhesive of agricultural machinery is suitable for the mating surface of worn bearing with the wear value not exceeding 0.2mm. In addition, the use of adhesives can also play a role in the loosening of anchor screws and the leakage of bearing lubricating oil.

e) Impregnate the coil with solvent-free paint

  In motor repair units, solvent-free varnish impregnation process is often used to insulate the motor during motor repair. When impregnating the motor coil, the stator coil is usually treated by manual drip impregnation, while the rotor coil is generally treated by rolling impregnation. This process only requires lifting equipment, pressure pump, paint tray and paint tank, which greatly reduces the demand of general impregnation process for diversified equipment.

f) The coil impregnated with solventless varnish is not only easy to operate, but also has remarkable technical and economic effects. Because the filling effect of solvent-free paint is full, it has the advantage of adequate impregnation compared with solvent paint, and the motor coil can be firmly bonded, so the solvent-free paint impregnation process is helpful to improve the motor repair quality and the thermal conductivity of the motor. In addition, the insulation treatment time of solvent-free paint is only ten hours or even several hours, which shortens the maintenance cycle of the motor and is of great significance for rush repair of the motor.

3. Conclusion

  This paper puts forward several improvement measures to solve the problem of multiple power consumption during motor repair. From the engineering practice of power saving in motor repair, it can be seen that the above five improvement measures are feasible and can achieve the effect of power saving in motor repair.