Insulation material heat rating corresponding to the temperature refers to the level of insulation material to allow long-term continuous operation of the temperature (not to be understood as the maximum working temperature of the insulating material)

　　Y-type: 90 ° C Insulating structure composed of un-impregnated cotton yarn, silk and paper or a composition thereof

　　Class A: 105 ° C An impregnated structure impregnated with or impregnated with liquid dielectrics (such as cotton yarn, silk and paper, or a composition thereof in transformer oil)

　　E grade: 120 ° C An insulating structure composed of a synthetic organic film, a synthetic organic enamel, or the like

　　B grade: 130 ° C Insulating structure consisting of impregnated or impregnated with a suitable resin, coated mica, glass fiber, asbestos, etc., and other inorganic materials, suitable organic materials or compositions thereof

　　F-grade: 155 ° C Insulating structure consisting of a suitable resin bonded or impregnated, coated mica, glass fiber, asbestos, etc., and other inorganic materials, suitable organic materials or compositions thereof

　　H grade: 180 ° C Insulating structure composed of a suitable resin (e.g., silicone resin) bonded or impregnated, coated mica, glass fiber, asbestos or the like or a composition thereof

　　C grade: Insulating structure composed of a material such as mica, ceramic, quartz or the like which is adhered or impregnated with a suitable resin, coated mica, glass fiber,