Insulating material is a material that does not conduct electricity at the allowable voltage, but it is not absolute_ For non-conductive materials, conduction, polarization, loss, breakdown and other processes will also occur under the action of a certain applied electric field strength, and aging will occur after long-term use.

Its resistivity is very high, usually in the range of 1010 ~ 1022 Ω· M. For example, in the motor, the insulating material around the conductor will isolate the turns and the grounded stator core to ensure the safe operation of the motor.

Insulating materials, also known as dielectrics, refer to materials that are non-conductive or extremely conductive under the action of DC voltage, and their resistivity is generally greater than 1010 Ω· M. The main function of insulating materials is to isolate the charged conductors with different potentials in electrical equipment, so that the current can flow according to a certain path. It can also play the role of mechanical support and fixation, arc extinguishing, heat dissipation, energy storage, moisture-proof and mildew proof, or improve the potential distribution of electric field and protect the conductor. Therefore, the insulating material is required to have as high insulation resistance, heat resistance and moisture resistance as possible, and a certain mechanical strength is also required.