Analysis of Vacuum Continuous Impregnation of Motor Winding

Analysis of Vacuum Impregnation Process of Motor Winding

The impregnated insulation treatment process of the motor windings, from immersion, namely ordinary impregnation to multiple impregnations, to drip leaching, roll immersion and vacuum pressure impregnation, and finally to the continuous immersion, drip leaching and roll immersion in a continuous process, formed a series of The diversification of mechanical continuous operation, computer technology and PLC technology control dipping process, in the past two years, has also formed a new type of insulation technology, namely vacuum continuous impregnation process. To facilitate the understanding of vacuum continuous impregnation process, the following vacuum continuous impregnation process and ordinary immersion, dripping, roller dipping, vacuum pressure impregnation and other insulation processes for comparative analysis.

2 various process principles and comparison of vacuum continuous impregnation and other process principles and process comparison are shown in the following table.

3 The function and analysis of continuous vacuum impregnation process In vacuum continuous impregnation process, the maximum absolute pressure is one atmosphere pressure. Therefore, vacuum is the main role of vacuum continuous impregnation process, and continuous is only the auxiliary function of vacuum continuous impregnation process. The purpose of the vacuum is to increase the impregnation quality and continue only to increase the impregnation yield.

3.1 Vacuum effect of vacuum continuous impregnation process: The vacuum effect of vacuum continuous impregnation process mainly includes two processes: one is vacuum exhaust, and the other is vacuum impregnation. Its role is to remove air, moisture and residual solvents or volatile substances in the voids inside the workpiece. After the workpiece is pre-baked, it is pumped into the dip paint can. If the moisture, solvent or volatile matter inside the workpiece is not removed, and airbags still remain after the liquid is lost, the airbag expands at high temperatures to form a large air gap and volatilizes during the gel phase. When the object escapes, leave an external passage. When the product is exposed to moisture, or other media invades the insulating inner layer along the channel, it will cause the same consequences as ordinary impregnation.

3.1.1 Vacuum evacuation of continuous vacuum impregnation process The workpiece after pre-bake dewatering process is placed in a vacuum impregnation tank and vacuumed to remove the air, moisture, volatiles and other gases from the workpiece, and the paint is vacuumed. Do a good job of preparing pressure differentials.

Theoretically, the higher the vacuum vacuum of a vacuum impregnated can, the better. However, the higher the vacuum, the higher the equipment performance and the higher the cost. Therefore, the vacuum vacuum impregnation tank vacuum; to a certain extent by the vacuum continuous impregnation process application object and equipment cost restrictions. Also, the higher the exhaust vacuum, the longer the pumping time. The continuous vacuum impregnation process is suitable for continuous operation and mass production, which limits the extension of the pumping time of the exhaust vacuum.

3.1.2 vacuum impregnation vacuum impregnation process impregnation cans vacuum paint, the workpiece was immersed in the impregnating paint, the paint liquid in the vacuum state, fully penetrated into the workpiece insulation structure.

The degree of vacuum after vacuum paint delivery, that is, the vacuum parameters of the paint, should be such that the active diluent components in the impregnating paint solution do not escape in large quantities. The amount of this volatile component will determine whether the curing of the insulating varnish can reach the final degree of hardening. Excessive vacuum can also cause “foaming” and “atomization” of the impregnating varnish, affecting and impairing the filling and curing. Therefore, the vacuum level of the impregnating lacquer is also limited by the amount of solvent or diluent and other volatile substances in the lacquer solution that escapes the vacuum.

3.2 Pre-baking of vacuum continuous impregnation process Before the impregnation and under normal pressure conditions, the workpiece is placed in a certain temperature in advance for a certain period of time so that moisture, solvents and other volatile substances inside the workpiece can be fully volatilized, and the workpiece can be The heat is obtained so that under exhaust heat conditions, vacuum exhaust and vacuum dipping can be performed. Appropriate pre-baking and proper residual heat temperature are effective ways to improve exhaust quality and improve the quality of impregnating paint. Obviously, the pre-supply temperature must be 100 or more.

Similarly, the pre-baking temperature and pre-bake time parameters of the workpiece are also limited by the insulation structure of the workpiece, the technical specifications, and the characteristics of the paint fluid.

3.3 Drying of workpieces by continuous vacuum impregnation process Drying of workpieces consists of two processes: gelation and solidification. In the vacuum continuous dipping process, due to vacuum impregnation, the volatilized part of the insulating liquid in the workpiece is basically discharged, the gel time is shortened, and the loss of the paint liquid is also reduced. The curing process, also due to the role of vacuum impregnation, makes the curing time of the vacuum continuous impregnation process shorten, and because of the reduction of the volatile part after vacuum impregnation, the harmful odor emitted during the curing process is also greatly reduced.

In particular, the use of a special insulating paint, in all aspects better, and the drying time and drying temperature are significantly reduced, significant energy savings.

3.4 Vacuum characteristics of insulating impregnating varnish The vacuum characteristic of varnish impregnating varnish means that the varnish does not “foam” and “atomize” in the vacuum environment at the impregnation temperature, the varnish volatilization and vacuum time and the varnish Viscosity is a function of vacuum time.

The best effect is to pre-vacuum the impregnating varnish, or after the impregnating varnish is poured into the varnish can, to maintain vacuum for a period of time to remove the vapour. Therefore, there are special requirements for the insulating paint used.

That is, under a certain vacuum process parameter environment, even if a small amount or part of the solvent or diluent and other volatile substances in the lacquer escapes, the final curing of the insulating lacquer in the workpiece is performed until the workpiece is in a gel and curing process. However, it is still the final degree of hardening. This is a unique characteristic of the vacuum continuous impregnation process insulation paint and vacuum impregnation, which complement each other and coordinate with each other. It is also one of the characteristics that the vacuum continuous impregnation process insulation paint must distinguish from other process insulation paints.

3.SV vacuum continuous impregnation process advantages In the scope of application of vacuum continuous impregnation process, the advantages of its role is mainly reflected in the following five aspects: improve the integrity due to vacuum impregnation, so that insulating paint is almost completely filled with insulation inside, strengthening the entire winding The integrity of the windings does not allow the parts to move individually during operation, which reduces the risk of failure due to wear.

Improve the ability to withstand environmental conditions due to vacuum impregnation, the entire winding is impregnated with the paint tightly sealed, the surface of the paint film is smooth and glossy, so that pollutants, moist gases and chemical gases can not enter the inner layer, eliminating the failure caused by the conductive media bridging .

Reduces operating temperature and temperature rise due to vacuum impregnation, complete filling, good insulation paint replaced internal air gap, improved thermal conductivity, low temperature motor can generally reduce temperature rise 5-10T. Strengthen environmental protection due to vacuum impregnation, the entire impregnation The process consists of putting paint and impregnating paint, which are carried out and completed under completely closed conditions. With the impregnation of a special vacuum continuous impregnating varnish, the entire drying process includes gelling and solidification. The volatilization is rather small and there is little odor. Distribute. Improve the working environment and meet environmental requirements.

Energy conservation and cost reduction Due to the use of vacuum impregnation and special insulation paints, the drying time is reduced by one-fifth compared to ordinary immersion, and the drying temperature is reduced by 10-20 compared to ordinary immersion. 4. Conclusion Vacuum continuous impregnation insulation technology is the development of today's science and technology and information industry. The product of the times is a development of the application of vacuum pressure impregnation technology. It is a supplement to the application of vacuum pressure impregnation to small, large-volume, high-demand winding impregnation processes. It is also an energy-saving and environment-friendly insulation impregnation process. It is suitable for vacuum continuous impregnation insulation treatment of motors for automobiles, motorcycles, power tools, micro-motors, small motors, electrical coils, and household electrical, electrical and electronic transformers and small transformer coils. The thickness of (turning to page 40) is detrimental to the insulation performance of the whole machine. When polishing the bonding area and commutation area of the rotor plate, attention should be paid to the pressure of the casting wheel on the rotor plate so that the polished surface is not only smooth and bright, but also not too large in pressure, otherwise it may cause internal insulation of the rotor plate. damage.

The mechanical dimensions of rotor plates are generally not routinely tested unless specifically required.

4 Verification of the electrical properties of the rotor sheet Several methods for the inspection of the rotor sheet are mainly electrical tests. Because it is related to the performance of the complete machine, so the general manufacturers for the electrical performance of the rotor sheet to do the full inspection.

4.1 Resistance method This method is simple and it is also a method that is used more often now. It only needs a micro-ohmmeter. The tester measures the measurement points at corresponding positions on the rotor chip, and compares the consistency of the multiple sets of data displayed on the micro-ohmmeter with the set values to determine whether the electrical properties of the rotor sheet are acceptable. The feature of this method is simple, but relatively difficult to operate. During the test, the tester shall keep the four contacts (a pair of current contacts, and a pair of voltage contacts) of the micro-ohmmeter respectively in contact with the corresponding two bars of the rotor plate under test, and the rotor The width of the guide bar is wide and the operation is still convenient. If the diameter of the rotor piece is small and the guide bar is fine and dense, it is difficult to test with this method. This method can only detect the on-off, short-circuit and short-circuit conditions of the rotor, but it cannot reflect the insulation of the rotor, and the inspection accuracy is not high and the efficiency is low.

4.2 Inductance Method Inductance method uses the principle of inductive coupling to regard the rotor piece as a closed inductor, and couples the high frequency signal to the windings of the rotor piece. After passing through the mutual coupling, the signal is checked to determine whether the rotor piece is qualified or not.

This method is easy to operate. Simply place the inspected rotor piece on the shaft of the device and close the cover to determine the rotor piece by the indicator light. Insufficient: The reason is that it needs to correspond to the structure of the rotor to be tested (diameter of the rotor, the number of pairs of poles of the motor, etc.), that is, a test device can only test the rotor of the corresponding model, which results in a test. The complexity of the equipment and the waste of funds. In the same way, this method can only judge the on/off and short-circuit of the rotor. 4.3 Oscillation method Oscillation method is to regard the rotor piece as an oscillation circuit that consists of a resistor, a capacitor, and an inductor. Apply a step voltage to it to determine whether the rotor piece is qualified by observing its oscillation waveform. The following waveforms are different fault conditions of the same type of rotor blade. The waveform of a qualified rotor is shown and its waveform is unchanged during the test. The waveform shows that there is an open circuit point in the rotor plate, which is basically at the inner and outer welding points. And it is also very regular attenuation oscillation, but compared with it can be seen that its oscillation frequency is higher than the normal waveform, and its waveform is changed in the test. This reflects that there are different degrees of "short-circuit" conditions inside the rotor plates. This "short circuit" is not caused by the direct contact of the conductors, but by the thinning of the insulation layer between the conductors. After installing such a rotor chip, if the operating current exceeds the standard, the heat is severe, and if it is heavy, the motor is burned. Therefore, after classifying the rotor plates of such waveforms, they can be reprocessed by vacuum impregnation to reduce losses. The situation shown is a direct short circuit between the rotor blade bars.

The oscillation method has the characteristics of simple operation, accurate judgment, high efficiency, and good repeatability, and it can achieve 100% consistency and accuracy. Can meet the needs of continuous production of large-scale production lines. In the inspection of more than 100,000 pieces of rotor discs of various specifications, the qualified and unqualified rotor discs detected by this method were used for installation tests, respectively, which proved that the method was accurate.

5 Conclusion Testing the rotor by the oscillation method not only reflects the resistance, inductance and capacitance of the rotor, but also measures the quality of the rotor. The rotor sheet produced by the corrosion method and the rotor sheet produced by the stamping method can be clearly seen from the waveform of the batch. The stamp sheet has good waveform consistency and high yield, which is good for the stability of the product performance. The guarantee. It is even possible to find rotors with almost identical waveforms, which is useful for special occasions.

The detection speed of the oscillation method is also unmatched by the first two methods.

Taking a 12cm rotor plate as an example, a test piece is taken at an average of 10 seconds. The effective working time per day is 6 hours, and 2160 pieces per person per day can be detected. Through 250 days in the whole year, a staff member can detect 540,000 rotor pieces in one year, which is sufficient to meet the needs of two production lines with a daily production capacity of 1,000 units.

This method is also applicable to the rotors of some micro-motors with iron cores. The authors have made significant tests. (no