Insulating paper is a composite insulating material that is often used when the motor winding adopts the enameled wire scheme. The material is made of insulating materials of different materials and bonded by special glue to make different insulation grades and heat resistance grades to meet the needs of motor windings with different performance requirements
In the manufacturing process of motor windings, insulating paper is mainly used for the insulation between the windings and the iron core slots, as well as the phase-to-phase insulation of the three-phase motor windings. In practical applications, the insulating paper is cut into different shapes and sizes according to the actual insulation requirements. When the insulating paper is used for ground insulation and interlayer insulation material in the tank, it is generally cut into strips according to the size of the iron core. Its size should meet the basic requirements of winding insulation and electrical clearance; when insulating paper is used as the interphase insulation of a three-phase motor, it is more applied to the end, and its specific shape is determined according to the actual winding insulation requirements
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composite insulating material used for motor windings, whether used as ground insulation or phase insulation, must be able to withstand the ground insulation voltage and the phase insulation voltage during the motor operation. In order to ensure that the insulation performance requirements do not deteriorate, during the production and processing of the motor windings, the composite insulation material should not have adverse effects such as delamination and blistering, and must be able to withstand the specified electric field impact.
In addition to the quality level of the insulation material itself, the motor production and processing technology and quality management control are particularly critical to the application effect of the insulation material. Some bad habits or mistakes may cause electrical quality problems.
(1) Insulation damage caused by poor core quality. The iron core groove of the motor is not smooth or there are foreign objects, the iron core groove bounces seriously, and the brutal operation of the wire embedding process may cause damage to the insulation layer and breakdown failure.
(2) Quality problems caused by inappropriate slot insulation dimensions. For the insulation in the slot, the width and length of the material are very important. The width part and the insulating cover strip of the iron core slot together envelop the electromagnetic wire in the slot to ensure that the winding and the iron core are isolated by insulation; the insulating paper must extend out of the iron core Notch to ensure that the electrical clearance and creepage distance between the winding and the ground, and the out-of-phase winding meet the requirements. In the actual operation process, the breakdown problem caused by the inconsistent size of the insulating material will occur from time to time, especially in the case of manual operation, human factors are the main cause of the problem.
(3) Problems that often occur in end insulation. For three-phase motor windings, whether it is a stator winding or a rotor winding, the end-phase insulation is very critical, especially for a few-pole motor. Because the winding span is relatively large, the corresponding inter-phase insulation area is also large, and the phase-to-phase insulation is most likely to shift during the winding binding process, which causes the insulation effect of the out-of-phase winding to deteriorate. Or, the insulation material is broken due to the shaping requirements during the binding process, which is also one of the reasons for the insulation failure between phases.
