When a motor is rewinding, many insulation material is used between each winding, winding and stator etc. Insulating materials are classified by considering their properties. They are essentially nonmetallic organic or inorganic, natural or synthetic. An ideal insulating material should have,

1. High dielectric strength sustained at elevated temperatures.
2. High resistively of specific resistance
3. Low dielectric hysteric
4. Good thermal conductivity
5. High degree of thermal stability

 Useful insulation materials are described below. Mica, Millinex Paper, Nomax paper , Empire cloths, Prespan, Fiberglass sleeves



Insulation Class

Insulations have been standardized and graded by their resistance to thermal aging and failure. Four insulation classes are in common use. For simplicity, they have been designated by the letters A, B, F, and H. The temperature capabilities of these classes are separated from each other by 25° C increments.