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 insulations can withstands a temperature of up to 90°C and it is typically made of cotton, silk, or paper.
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 insulations can withstands a temperature of up to 120°C.
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 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 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 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.