Coil Winding

Coil winding is the process of wrapping insulated electrical wire into a series of turns to form a coil. When electric current passes through the winding, it produces a magnetic field. A changing magnetic field can also induce voltage in a winding, making coils important in devices such as transformers, inductors, solenoids and current transformers.

The winding may be formed around a bobbin, a magnetic core or another supporting shape. Some coils are air-core designs, meaning they do not use a ferromagnetic core to concentrate the magnetic field. Others use core materials selected for the component’s operating conditions. The number of turns, wire size, winding shape and core material all influence electrical behavior.

For example, increasing the number of turns generally increases inductance when the other design factors remain the same. Wire size affects the coil’s resistance and the amount of current it can carry without excessive heating. The arrangement of turns and insulation between conductors can also affect the space the coil occupies and its performance in the finished circuit.

Coil winding can involve a single winding or several separate windings on the same component. A transformer, for instance, uses primary and secondary windings to transfer energy through magnetic coupling. A solenoid uses its winding to create magnetic force for an actuator or valve.

Because different applications have different electrical and mechanical requirements, the winding pattern and materials must be selected to match the intended use. Even relatively small changes to the winding configuration can affect a component’s electrical characteristics, dimensions and operating temperature.