Rectangular Enameled Copper Wires are most used in power transformers and AC UHV transformers. DC converter transformers use enameled rectangular wires instead of round wires. The most commonly used are acetal enameled copper rectangular wires. Heat-resistant enameled flat wires are used in dry-type transformers.

In general, enameled copper wire must meet the requirements of a variety of uses and manufacturing processes. The former includes its shape, specifications, ability to work at high temperatures for short and long periods of time, as well as withstanding strong vibration and centrifugal force at high speeds in some occasions, resistance to corona and breakdown under high voltage, and resistance to chemicals in special atmospheres Corrosion, etc. The latter includes the requirements for stretching, bending and abrasion during winding and embedding, as well as swelling and erosion during dipping and drying.