Analysis and Discussion of Turn-to-turn Insulation Faults in Low-voltage Motor Windings

For motor products, the winding is its most core components, once the winding problems, motor repair costs will be very high. Electrical faults in the motor winding, the most common faults for the ground, turn and three-phase motor phase-to-phase insulation failure. Relatively speaking, these three kinds of electrical insulation failures, turn-to-turn failure is almost no possibility of repair, that is, once the turn-to-turn failure, you must replace the winding.

Turn-to-turn failure is the motor turns and turns between the insulation breakdown failure, the more turns of the winding, the higher the chance of turn-to-turn failure, in order to avoid turn-to-turn insulation failure, you can choose from the electromagnetic wire, winding design, process improvement and other aspects of measures.

For low-voltage motor products, stator windings are mostly soft windings, that is, the use of enameled wire embedded in a loose way. The number of turns of such windings is relatively more, the total area of turn-to-turn insulation is also relatively large, for the paint film requirements of the electromagnetic wire is relatively high, electromagnetic wire paint film thickness, uniformity, adhesion, tensile, twisting, voltage, heat, corrosion resistance and other properties should meet the requirements. Therefore, the choice of excellent performance of the electromagnetic line is to prevent the motor winding turn-to-turn insulation failure must be.

In addition to the quality of the electromagnetic wire in line with the quality of the motor core is crucial, on this issue we do not repeat here. Here to particularly emphasize is the winding process to meet the degree of processing technology, in many of the motor factory, in the winding, embedded wire, wiring and shaping link there is the fact of barbaric operation, it is easy to cause the insulation of the electromagnetic wire damaged problem, which is also a major factor leading to the frequent occurrence of turn-to-turn failures.

There is also a problem for the selection of inverter motor solenoid, relative to the frequency motor, inverter motor is applied voltage is not sinusoidal, but by a series of high-frequency pulses of square wave composed of analog sinusoidal, and thus the motor windings are always in the steep impulse voltage work, which requires the motor windings have a better resistance to corona ability. Thus. Frequency conversion motor using ordinary wire has certain quality risks, about frequency conversion motor with electromagnetic wire, many manufacturers of electromagnetic wire also have a special study.

The above content we are mainly embedded in the main soft winding for the inter-turn problem, especially for large motors, low-voltage motors using molded windings is also a very effective measure to avoid inter-turn problems, including the rotor winding for wire-wound motors, soft windings out of the problem of the situation is more, and the use of molded windings of the reliability of the motor to be relatively good.

Of course, the theoretical design and the actual manufacturing process is closely related to the manufacturing process of the soft winding is relatively simple and convenient, which is most of the manufacturers according to one of the reasons for the use of the process. However, if the use of molded windings, motor ventilation and heat dissipation effect is better, the occurrence of turn-to-turn failure is also less. In addition to the winding process, the winding of the dip baking process is particularly critical, the link can make up or repair the production process for the insulation of some of the small damages, can be between the turns and turns through the impregnation of paint connected to each other into a solid insulated whole, the insulation of the motor, the mechanical properties of the motor to play a vital role in improving the quality.