Transformer winding material refers to the circuit part of transformer, which is wound by copper conductor or aluminum conductor with high conductivity, and is used in power system. The winding shall have sufficient insulation strength, mechanical strength and heat resistance.
Windings are usually divided into layer type and cake type. The wire turns of the winding are arranged in sequence along its axis and continuously wound, which is called layer winding. Generally, each layer of layer winding is cylindrical, so the winding composed of two layers is called double-layer cylindrical type; A multi-layer cylinder is called a multi-layer cylinder.



The wire turns of the winding are continuously wound along its radial direction to form a cake (section), and then the winding composed of many cakes arranged along the axial direction is called cake winding. It includes continuous type, plug-in capacitor type and tangled type.
The winding between layer type and cake type includes foil winding and spiral winding. The form of foil winding is also cylindrical, and the wire turns are continuously wound along the axial direction. Generally, one turn is one layer, so it can belong to layer winding. Spiral winding is generally one turn for each cake, or one turn for two cakes or four cakes. Each turn is continuously wound along the axial direction, but the form is composed of each cake, so it can belong to cake winding.

The layer winding has compact structure, high production efficiency and good resistance to impulse voltage, but its mechanical strength is poor. The cake winding has good heat dissipation performance, high mechanical strength and wide application range, but its performance of withstanding impulse voltage is poor.