Kapton® CRC - partial discharge resistant insulation

December 3, 2019 By
CMC Klebetechnik GmbH

The requirements for energy efficiency are becoming ever more stringent. At the same time, however, electrical devices should become smaller and smaller - or at least not larger.

The high-performance Kapton® film from DuPont helps to achieve this goal. This is because the high temperature resistance, the very long-lasting electrical properties of the polyimide film and the high mechanical strength allow compact designs. Even when the heat dissipation of a transformer or an electric motor becomes increasingly difficult due to the packing density, Kapton retains its good insulating properties. In this way, Class C motors can also be built, or extremely extended running times can be achieved for Class H motors. This is because one of the main reasons for insulation failure is premature aging due to the effects of heat.

In modern drive trains, however, insulations are stressed in yet another way: by the high pulse load of pulse-width modulated controls with steep rising edges and overshoots in the R-L-C circuit. This affects the motor windings as well as those of the transformer transformers in the frequency converters.

Kapton® CRC protects against this additional danger. This Kapton variant offers significantly improved resistance to the damage effects of so-called partial discharges. This is because such corona discharges particularly affect polymer insulations and destroy them in the long term.

Kapton® CRC polyimide films have a drastically increased service life against repeated partial discharges!

In standardized test at DuPont: >30 times longer service life of Kapton® CRC compared to PD like Kapton® HN; see also comparison.

The film owes this huge increase in service life to the addition of inorganic insulation materials. At the same time, these increase the thermal conductivity of the insulation film, which contributes to improved heat dissipation. As a result, higher power density can be achieved in the same installation space. This normally means higher energy efficiency, but without the disadvantage of a shorter service life.

Kapton® HN (the standard variant) and Kapton® CR are therefore also preferred for use in traction motors, large high-voltage motors for industrial applications, in generators and transformers. Kapton® CRC is a mechanically more stable version when it is important to withstand high compression pressures in the winding compound. 

Thanks to improved performance, longer life, excellent thermal stability and excellent corona resistance, Kapton® insulations enable you, the customer, to have small designs, high power density and a large safety margin.

Examples of applications: rods, armature rods of generators or high-voltage motors, safety transformers in the medium-voltage range (charging stations Emobility), frequency converters in PWM operation for electromobility.