Wire-wound resistor

This refers to the resistance of the winding wrapped around the core of a transformer or choke coil. Copper wire, which has low electrical resistance, is mainly used for the winding. When current flows through the winding, losses occur due to its resistance, which is known as copper loss. Copper loss is also called load loss and increases in proportion to the square of the current. Therefore, to reduce the losses of a transformer or choke coil, it is desirable for the winding resistance to be as low as possible.