Insulation Class

The electrical insulation system for wires used in generators, electric motors, transformers, and other wire-wound electrical components is divided into different classes by temperature and temperature rise. The electrical insulation system is sometimes referred to as insulation class or thermal classification.

Sl. No.Insulation ClassTemperatureMaterials Used
1.Y90°CCotton, Silk, Paper, Wood (without impregnation)
2.A105°CCotton, Silk, Paper, Wood (with impregnation)
3.E120°CWire, Enamel
4.B130°CMica, Asbestos, Glass fibre (with suitable clothing)
5.F155°CMica, Asbestos, Glass fibre (with suitable clothing)
(can withstand 25°C extra temp.)
6.H180°CCombination of Mica, Asbestos, Glass fibre
7.C>180°CMica, Porcelain, Glass, Quartz with or without an inorganic binder

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