Insulation material classes

Insulation material classes are defined in DIN EN 60085. An insulating material class defines insulating materials (such as enameled copper wire) in terms of their maximum operating temperature. The classes refer to both electrical insulating materials (EIM) and electrical insulating systems (EIS). In electrical engineering, electronic components can reach very high temperatures, which can impair or destroy insulation. The insulating material classes are therefore intended to prevent thermal decomposition from destroying the insulating materials during use or rendering them inoperable. The insulating materials are divided into heat classes with different limit temperatures according to their heat resistance. These temperatures must not be permanently exceeded during operation in order to guarantee a long service life.

RTE* relative thermal resistance index

Insulation class	RTE*	Thermal class
Y	≥ 90° but < 105°	90°C
A	≥ 105° but < 120°	105°C
E	≥ 120° but < 130°	120°C
B	≥ 130° but < 155°	130°C
F	≥ 155° but < 190°	155°C
H	≥ 190° but < 200°	180°C

Insulation class

RTE*

Thermal class

≥ 90° but < 105°

90°C

≥ 105° but < 120°

105°C

≥ 120° but < 130°

120°C

≥ 130° but < 155°

130°C

≥ 155° but < 190°

155°C

≥ 190° but < 200°

180°C