Insulation class

Insulation level

l   Class A：Class A insulation includes impregnated organic fiber materials such as cotton yarn, silk, paper, and enamel on ordinary enameled wires. Commonly used in transformers, the maximum allowable operating temperature of Class A insulation is 105°C.

l   Class E：Class E insulation includes films made of polyester resin, epoxy resin, triacetate fiber, etc., enamel on polyvinyl acetal high-strength enameled wire, etc. Used in small and medium-sized AC and DC motors, the maximum allowable operating temperature of Class E insulation is 120°C.

l   Class B：Class B insulation includes materials and combinations made of inorganic materials such as mica, asbestos, and glass fibers using organic paint or resin as a binder, and enamel on polyester high-strength enameled wires. Generally used in large and medium-sized synchronous machines and medium- and small-sized AC and DC motors, the maximum allowable operating temperature of Class B insulation is 130°C.

l   Class F：Class F insulation includes mica, asbestos, glass fiber and other inorganic materials, and is made of silicone hydrocarbon resin, synthetic resin paint, or alkyd or epoxy resin whose heat resistance meets the requirements of this class as a binder or a combination thereof. , the maximum allowable operating temperature of Class F insulation is 155°C.

l   Class H：Class H insulation includes materials made of silicone organic materials and inorganic materials such as mica, asbestos, and glass fibers using silicone organic paint as a binder. It is mainly used in applications that require minimizing size and weight, such as aviation motors, crane motors, traction motors, etc. The maximum allowable operating temperature of Class H insulation is 180°C.

l   Class C：Class C insulation includes using raw mica, quartz, glass fiber, etc. alone, or adding asbestos, glass fiber fabric or other products treated with organic resins with particularly good thermal stability, polyimide impregnating paint, and polyimide. Amine-based enameled wire enamel, polyimide film, etc. Class C insulation is an insulating material with relatively high requirements and is currently being promoted. Its maximum allowable operating temperature is above 180°C.