Electric wires refer to conductors used for transmitting electrical energy. They are classified into bare wires, magnet wires, and insulated wires. Bare wires lack an insulating layer; this category includes flat copper and aluminum wires, overhead stranded conductors, and various shaped profiles (such as shaped wires, busbars, copper bars, aluminum bars, etc.). They are primarily utilized in outdoor overhead power lines as well as in indoor busbar systems and switchgear cabinets.
Magnet wires are insulated conductors designed to generate a magnetic field when energized, or to induce an electric current when placed within a magnetic field. They are predominantly used in the windings of electric motors and transformers, as well as in other electromagnetic devices. The conductor material is typically copper wire; it requires a thin insulating layer and must possess excellent electrical and mechanical properties, in addition to characteristics such as heat resistance, moisture resistance, and solvent resistance. Different characteristics can be achieved by selecting different insulating materials.
Magnet wires primarily fall into two categories: enameled wires and wrapped wires. Enameled wires are produced by coating a bare copper wire with an insulating varnish; their insulating layer is thin, resulting in a compact size, and they are widely employed in various motors, electrical appliances, and instrumentation. The performance characteristics of enameled wires vary depending on the nature of the insulating material used. Wrapped wires include types such as yarn-wrapped, silk-wrapped, glass-fiber-wrapped, paper-wrapped, and plastic-film-wrapped wires. Among these, yarn-wrapped and silk-wrapped wires are likely to be phased out due to their poor heat resistance and relatively large physical volume. Glass-fiber-wrapped wires are produced by wrapping glass fibers around a round copper conductor and impregnating the assembly with silicone resin; they can withstand high temperatures of up to 180°C and exhibit excellent insulating properties and mechanical strength. Paper-wrapped wires are primarily used in oil-immersed transformers. Plastic-film-wrapped wires are manufactured by coating a polyimide film with an adhesive, wrapping it around a conductor, and then heat-curing it. Their insulating layer is tough and elastic, making it easy to wind while offering excellent abrasion and heat resistance; they are widely utilized in equipment for applications such as aerospace technology.
