Saturday, 30 July 2016

Electrical Insulation Classes


Insulation Classes based on the temperature it can sustain is classified into the following classes:



The following are brief explanations of these insulation classes:

Class-Y Insulation: 

Class-Y insulations can withstands a temperature of up to 90°C and it is typically made of cotton, silk, or paper.

Class-A Insulation: 

Class-A insulations can withstands a temperature of up to 105°C. It is made of reinforced Class-Y materials with impregnated varnish or insulation oil.

Class-E Insulation: 

Class-E insulations can withstands a temperature of up to 120°C.

Class-B Insulation: 

Class-B insulations can withstands a temperature of up to 130°C. This has a form that inorganic material is hardened with adhesives. This is the first insulator using this structure.

Class-F Insulation: 

Class-F insulation can withstands a temperature of up to 155°C; for example, made of Class-B materials that are upgraded with adhesives, silicone, and alkyd-resin varnish of higher thermal endurance.

Class-H Insulation: 

Class-H insulations can withstands a temperature of up to 180°C. It is made of inorganic material glued with silicone resin or adhesives of equivalent performance.

Class-C Insulation: 

Class-C insulations withstand a temperature of up to 180°C or higher. It is typically made of 100% inorganic material.


As explained above, electrical insulation is classified with its maximum allowable temperature. By adopting an insulation technique of higher thermal endurance, the size of electrical machine can minimized.

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