One netizen claimed that the motor windings had serious electrical breakdown problems. From the actual pictures, it can be seen that the motor windings and the stator core had a ground fault. As for the cause of the problem, the motor user and the motor manufacturer have different opinions.

Compared with low-voltage motors, local discharge usually occurs in the insulation structure of high-voltage motors, but the size, quantity and location of local discharge depend on the design, material, manufacturing process, quality, operating environment and aging condition of the motor. In view of the local discharge problem that is difficult to avoid in high-voltage motors, necessary avoidance measures will be taken during the design and manufacturing process of the motor windings, such as thicker insulation layers, tightness of insulation wrapping, anti-corona measures, and coordination between stator windings and iron cores. In order to prevent the generation of corona, anti-corona paint will be applied on the surface of the winding iron core. These measures are all aimed at weakening the adverse effects of discharge problems on the windings during motor operation.

Compared with high-voltage motors and variable-frequency motors, low-voltage motors have relatively fewer discharge problems, so the insulation structure of the motor windings is relatively simple. However, unreasonable processes during the winding processing will also cause the insulation of the motor windings to be damaged, resulting in quality problems with the ground, between turns, and between phases. Here, we summarize a few opinions to share with you.

First, the protection of insulation compliance during winding coil manufacturing. Whether it is electromagnetic wire with its own insulation or electromagnetic wire with external insulation, the matching compliance of the insulation layer and the insulation structure of the motor, as well as the protection during the manufacturing process are crucial. Once the insulation layer is damaged, there will be a major quality risk during the operation of the motor.

Second, the standardization of the manufacturing of the outer insulation coil. For high-voltage motors and some special-purpose motors, when the electromagnetic wire outer insulation process is adopted, it should be ensured that the layers are dense enough to eliminate the gaps and bubbles between the insulation layers to the maximum extent, and prevent the problem of air ionization discharge during the operation of the motor.

Third, during the wire embedding process, especially for the protection of the first coil, since the coil is subjected to severe force when the stator winding enters the iron core, a large deformation will cause the coil to deform, affecting the coordination with the iron core. Especially after the insulation layer is damaged, deformation and insulation defects may cause serious electrical breakdown during the operation of the motor.

Fourth, the compliance of the varnishing process. Insulation curing is an enhanced measure to effectively control and reduce the insulation problems of motor windings. Necessary varnishing equipment and standardized process guarantees are important means to solve the temperature rise and feasibility of motor windings.

Fifth, during the operation of the motor, the degree to which the protection level satisfies the safe operation of the motor. When selecting a model, the user should communicate with the supplier according to the actual situation and choose an appropriate motor protection level; and the motor manufacturer should strictly process and assemble parts and components in accordance with the corresponding protection level requirements, and should not arbitrarily simplify the assembly requirements of parts and motors.