Paper-covered wire is a winding wire made from oxygen-free copper rods or electrical round aluminum rods that are extruded or drawn through a specific mold size and then annealed. It is further wrapped with two or more layers of insulating paper (including telephone paper, cable paper, high-voltage cable paper, interturn insulating paper, etc.) on the copper (aluminum) conductor. It is suitable for oil-immersed transformer coils and other similar electrical winding applications. The bare copper (aluminum) electrical conductor produced by the extrusion process is an ideal material for manufacturing paper-covered cable wires.