TECHNICAL ARTICLE

Kapton Polyimide Films for Traction Motors in Railway Trains

2021-11-10 17:27  |  By: ZTELEC  |  132click

High performance polyimide (PI for short) films can be used for insulation in high power electric locomotives, AC generators and various high precision motors. PI related products have great technical difficulties and high value added.

PI films used for traction motors in railway trains are now being developed towards high power and light weight due to the restriction of space in the trains. To obtain higher power coefficient, the traction motors are required to be improved from two aspects: raising its operating temperature on the one hand and on the other hand reducing the main insulation thickness.

PI films for traction motors in high-speed railway trains

(1) Raise the operating temperature

The higher the insulation grade of motor system is, the higher the maximum working temperature it allows. For each grade the motor insulation system is elevated, its output power will be increased by about 10%~15%. Nowadays, the insulation grade of traction motors in railway trains all over the world has been gradually upgraded from Class F (thermal resistance 155°C) to higher heat resistance grade Class H (180°C) and Class C (200°C), and the power coefficient of motors has also been increased significantly. In motor insulation systems above class F, polyimide film is used as the main material for motor turn-to-turn insulation.

(2) Reduce the main insulation thickness

Reducing the thickness of the motor main insulation facilitates an increase in the effective area of the motor winding conductors, which will further increase the power of the motor. For instance, when mica belt and high-performance polyimide are used respectively for the same size and weight of motor main insulation systems, the power of the latter is remarkably higher.

ZTelec Group has introduced an advanced PI film production line, which offers high performance PI films with thermal resistance reaching 250℃. It comes in three colors: yellow, brown, and dark brown. Width of the PI film can be customized according to requirements.

PI film production line

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