Paper Insulated Multiple Wires
Twin and triple conductors combined under a common paper wrapping, for high-current transformer windings.
Twin and triple conductors are produced by combining two or three conductors run in parallel under a common insulation layer. Using parallel small cross-sections instead of a single large one markedly reduces the extra losses caused by skin effect and proximity effect at high frequencies.
They are also advantageous in winding: because the two or three wires are wound in a single pass and in a fixed position relative to each other, the winding geometry becomes repeatable and the gap between turns — and therefore leakage inductance — is reduced. They are widely used in transformer secondary windings, inductor and choke coils, and home-appliance motors.
Paper Insulated Multiple Wires Products
Paper Insulated Triple Flat Copper Wire
ISO-CU-KCT-3FTechnical Information
- Structure: twin (2 conductors) and triple (3 conductors) parallel
- Single-wire diameter: 0.50 – 2.50 mm (round), 2.00 – 8.00 mm width for flat
- Common insulation: enamel, glass-fibre wrap or film
- Thermal class: 155 (F) – 200 (N)
- Reference: IEC 60317-0-1, IEC 60317-0-2, IEC 60851
In choosing a multi-conductor, the single-wire section is set according to the skin depth at the operating frequency. As the frequency rises, the concentration of current in the outer region of the conductor section increases; splitting the section into parallel branches limits this concentration and lowers the effective resistance.
In the twin arrangement, the two wires staying in a fixed position under common insulation ensures balanced current sharing along the winding. Otherwise circulating currents form between the parallel wires and the total loss rises above what is expected.