Insulation materials for hybrid and fully electric cars
3 December, 2019 by
CMC Klebetechnik GmbH

Carl Benz's first "automobile" of 1886 still managed largely without electrics - the high-voltage ignition system represented almost the entire electrification. Today's vehicles, on the other hand, resemble "rolling switch cabinets" that place increasingly higher demands on the insulating materials as the electrification of the drive increases.

The so-called low voltage (48 VAC or 70 VDC) usually only requires functional insulation - the touch voltage is sufficiently low that people are not endangered. But even with 48 V (4 times the usual battery voltage in a car with a combustion engine), no significant drive power can be achieved - the wire cross-sections required for the flowing currents are simply too large.

Therefore, significantly higher voltage levels are used today in hybrid vehicles and even more so in all-electric vehicles. This prevents large amounts of copper from making the vehicle unnecessarily heavy. However, this is within the low-voltage directive (up to 1000 VAC and 1500 VDC). This places special requirements on insulation materials as well as clearance and creepage distances.

Specifications such as operating voltage, withstand impulse voltage, operating height, degree of contamination, thermal class, sensitivity to creepage path formation and other properties not only result in requirements for clearances and creepage distances, but also for the insulation material itself (see article Material suitability with regard to IEC 60664).

Kapton® HN and Kapton® FN (improved version with cti value 1) are virtually ideal insulation foils for providing sufficient, permanent and reliable isolation in the IT network or from the earthed network of the power feed in modern high-voltage concepts in electric vehicles. They help to reduce sizes and allow for very compact devices and equipment in e-vehicles. In addition, Kapton® MT+ with coatings of CMC adhesive technology ensures very good heat dissipation in the electronics area (e.g. charging device, battery management system and power electronics of the drive).

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