Insulation classes

Dr. Dietrich Müller GmbH

Insulation classes

Insulating materials can be classified into the following recognized classes:

Insulating material class A

Insulating material class A consists of materials such as cotton, silk, and paper when suitably impregnated or coated or when immersed in a dielectric fluid such as oil. Other materials or combinations of materials may be included in this class if it can be demonstrated by experience or testing that they can be operated at the Class A temperature.

Maximum Allowable Temperature: (IEC60034-1 & NEMA MG1-12.43): 105C, 221F.

Insulating material class E

Insulating material class E consists of materials or combinations of materials that have been shown by experience or testing to be capable of operating at a class E temperature (materials that have a degree of thermal stability that allows them to operate at a temperature 15 degrees higher than class A materials).

Maximum allowable temperature: (IEC60034-1 only): 120C, 248F.

Insulating material class B 

Class B insulation consists of materials or combinations of materials such as mica, fiberglass etc. with suitable bonding, impregnating or coating materials (note, some older applications used asbestos). Other materials or combinations of materials, not necessarily inorganic, may be included in this class if it can be shown by experience or testing that they can be operated at the Class B temperature.

Maximum Allowable Temperature: (IEC60034-1 & NEMA MG1-12.43): 130C, 266F.

Insulating material class F

Insulating material class F consists of materials or combinations of materials such as mica, fiberglass etc., with suitable binders, impregnating or coating materials, and other materials or combinations of materials, not necessarily inorganic, which experience or tests have shown to be capable of operating at the class F temperature (materials having a degree of thermal stability that permits them to operate at a temperature 25 degrees higher than class B materials).

Maximum Allowable Temperature: (IEC60034-1 & NEMA MG1-12.43): 155C, 311F.

Insulation class H

Class H insulation consists of materials such as silicone elastomer and combinations of materials such as mica, fiberglass, etc. with suitable adhesives, impregnating or coating materials such as suitable silicone resins. Other materials or combinations of materials may be included in this class if it can be demonstrated by experience or testing that they can operate at the Class H temperature.

Maximum Allowable Temperature: (IEC60034-1 & NEMA MG1-12.43): 180C, 356F.

Insulation class C 

Class C insulation consists of materials or combinations of materials such as mica, porcelain, glass, quartz with or without inorganic binder (note, some older applications used asbestos, which is now banned). Other materials or combinations of materials may be included in this class if it can be demonstrated by experience or testing that they can be operated at temperatures above the Class H limit. Certain materials or combinations of materials in this class have a temperature limit depending on their physical, chemical, and electrical properties.

Maximum allowable temperature: (IEC60034-1 only): >180C, 356F.

 

Share this post