Engineering Q&A
Classify the insulating materials as per operating temperature. Give two examples of each type.
in Testing and maintenance of electrical equipments by

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Insulation Classes 
Maximum permissible temperature (0C)
Insulating Material
1 Class-Y or O 
Cotton, silk, paper, press board, wood, cellulose-, PVC, VIR. (Cotton, silk, paper, cellulose, wood etc. Neither impregnated nor immersed in oil comes under this class. )
2 Class- A 
Cotton, silk and paper suitably impregnated with natural resins or immersed in oil come under this class.
3 Class- E
Laminated Cotton, Laminated paper Synthetic resin enamels. 
4 Class- B
Mica, glass fibers, asbestos with suitable bonding substances comes under this class. 
5 Class- F
Laminated asbestos, Glass fiber, and asbestos with suitable bonding substances of high thermal stability come under this class. 
6 Class- H
Mica, glass fibers, asbestos with suitable bonding substances such as silicones come under this class. Or adhesive coating. 
7 Class- C 
Over 1800
Porcelain, ceramics, glass, quartz. 

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