Paper Insulated Wires
Flat and round wires insulated with kraft, crepe, Dennison and thermal paper for oil-immersed transformers.
Paper-insulated conductor is the fundamental element of oil-type transformer technology. Cellulosic paper is wound layer by layer onto the conductor; after the transformer tank is evacuated, the insulating oil penetrates the paper's pores and paper and oil form an insulation system that works together. This system is a proven solution over service lives spanning decades.
The papers used comply with the requirements for electrical-purpose cellulosic paper under IEC 60554. Flat kraft paper is used in the linear winding sections, and crepe paper, thanks to its flexibility, at lead-outs and tight-radius bends. Thermally upgraded (Satinert) papers slow the ageing of cellulose and allow operation above class 105.
Paper Insulated Wires Products
Kraft Paper Covered Rectangular Aluminium Conductor
ISO-AL-KRF-F105
Crepe Paper Insulated Rectangular Copper Conductor
ISO-CU-KRP-F105
Crepe Paper Insulated Round Copper Conductor
ISO-CU-KRP-R105
Dennison Paper Covered Rectangular Copper Conductor
ISO-CU-DNS-F105
Technical Information
- Paper types: kraft, crepe, Dennison, Satinert (thermally upgraded)
- Paper thickness: 0.05 – 0.125 mm (per layer)
- Total insulation build increase: 0.25 – 2.00 mm (both sides)
- Thermal class: 105 (A) — 120 / 130 with thermal papers
- Reference: IEC 60554 (cellulosic papers), EN 13601 (copper conductor)
The main factor determining the life of cellulose insulation is temperature: every few degrees of rise in the hot-spot temperature markedly accelerates the rate at which the paper's degree of polymerisation drops. This is why, in winding design, the conductor section, paper thickness and oil-flow channels are sized together.
Moisture control is critical in paper-coated conductor. The product is shipped in moisture-proof packaging; keeping the relative humidity limited during storage before winding directly affects the length of the drying cycle and the final insulation resistance.