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Why do some three-phase motor windings have no phase-to-phase insulation?

Date:2023-07-29   Author:XINDA MOTOR

Phase-to-phase insulation is a special motor insulation performance requirement for multi-phase motors, that is, the insulation performance between coils of different phases of the motor winding must meet the electrical performance requirements of the motor. In theory, there can be multi-phase motors other than three-phase motors, but from the actual motor design and application, three-phase motors are most commonly used.

For the three-phase motor windings made of enameled wire, due to the turn-to-turn, phase-to-phase, and the distance between the winding and the iron core and the particularity of the insulation layer of the motor winding, the phase-to-phase The insulation performance of the electromagnetic wire cannot be completely satisfied by the insulation layer of the electromagnetic wire body, especially the damage to the insulation layer of the electromagnetic wire caused by the winding and embedding process, which further increases the quality hidden danger of the phase-to-phase insulation performance of the winding. During the manufacturing process, phase-to-phase insulation must be strengthened through necessary insulating materials, and the insulating materials used are mainly composite insulating materials such as DMD and NMN. For windings with better winding manufacturing process and higher quality electromagnetic wire materials, there are also cases where the external interphase insulation material is omitted, that is, the insulation layer of the electromagnetic wire completely meets the performance requirements of the interphase insulation.


For the winding with flat wire as the conductor material, due to the forming effect of the motor coil, the end of the motor can be effectively controlled and guaranteed by the space distance between the coils. Whether it is a high-voltage motor or a low-voltage motor, except for the same slot In addition to the necessary phase insulation materials between different phases, the interphase insulation performance of the windings is completely satisfied by the insulation layer of the conductors and the space distance from each other. This is the concept that some netizens have proposed that the three-phase motor windings do not have interphase insulation. From a theoretical analysis, there is phase-to-phase insulation of this winding, but no other insulating materials are added; for example, the thickness of the outer insulation layer of the stator coil of a high-voltage motor is sufficient to ensure the performance requirements of the phase-to-phase insulation of the winding, even at the winding end. There is no need to add other insulation to the overlapping parts of the inner part, especially the better VIP vacuum impregnation process, which further strengthens the insulation performance of the winding.