Common insulating materials are divided into three categories:
⑴ Inorganic insulating materials: mica, porcelain, asbestos, marble, glass, sulfur, etc. Used for winding insulation of motors and electrical appliances, switch soleplates and insulators, etc.
(2) Organic insulating materials: rubber, resin, shellac, cotton yarn paper, hemp, silk, rayon tube, etc. It is used for manufacturing insulating paint, outer insulation of winding wires, etc.
(3) Mixed insulating material: formed insulating material processed by two kinds of insulating materials.