There are mainly two kinds of electromagnetic wires: enameled wire and wound wire. Enamelled wire is made by coating insulating paint on bare copper wire. It has thin insulating layer and small occupation volume. It is widely used in various motors, electrical appliances and instruments. The properties of enamelled wires vary with the properties of the insulating materials used. Wrapped wires mainly include yarn wrapped wire, silk wrapped wire, glass wrapped wire, paper wrapped wire and plastic film wrapped wire, among which yarn wrapped wire and silk wrapped wire may be eliminated due to poor temperature resistance and large occupied volume. Glass wire wrapped wire is wrapped around round copper wire and impregnated with silicone resin. It can withstand 180 ℃ high temperature and has good insulation performance and mechanical strength. Paper wrapped wire is mainly used for oil immersed transformer. Plastic film wrapped wire is made of polyimide film coated with some adhesive and wrapped on the conductor. Its insulating layer is tough and elastic, easy to wind, wear-resistant and heat-resistant, and is widely used in aerospace and other equipment. Insulated wire is generally composed of conductive wire core, insulating layer and protective layer. The wire core can be divided into hard type, soft type, mobile type and extra soft type according to the use requirements. There are four kinds of wire cores: single core, two core, three core and four core. The insulating layer is generally made of rubber, plastic, etc. This kind of insulated wire is widely used in various instruments and meters, telecommunication equipment, power lines and lighting lines with AC voltage below 500V and DC voltage below 1000V.