Paper covered round wire is a type of winding wire that uses bare copper or aluminum wire as the conductor, with its exterior wrapped with kraft paper, Nomex paper, and other materials to form an insulating layer. It is mainly used in the manufacturing of windings for electrical equipment such as power transformers, instrument transformers, and reactors.
Paper Covered Round Wire Features
Insulation performance: The insulating paper layer has excellent voltage resistance in transformer oil, capable of withstanding power frequency withstand voltage tests of over 10kV/mm. The temperature resistance classes of different insulating papers vary significantly; for instance, ordinary kraft paper is suitable for 105—180℃ environments, while Nomex paper can operate stably for a long time at 220—240℃.
Mechanical properties: After annealing treatment, the elongation of the conductor is ≥15%, and the peel strength of the insulating layer is ≥1.5N/cm, which can withstand the tension and bending stress during the winding process. Due to higher rigidity, semi-hard conductor products can significantly enhance the winding’s ability to resist short-circuit impact.
Chemical properties: The chemical properties of paper covered round wire are related to the type of insulating paper. Kraft paper is commonly used in mineral oil; the two are well-matched and can adapt to weak acid and alkaline environments. Nomex paper is more suitable for silicone oil and has a wider range of acid and alkali resistance. Both are resistant to daily-used cleaning solvents.
Applications:
Oil-immersed transformers: In oil-immersed transformers, insulating oil and paper can form an “oil-paper composite insulation system” — the oil can fill the micropores of the paper to improve the overall breakdown strength; at the same time, the oil can dissipate heat and delay the thermal aging of the paper, which is an inherent advantage of paper
insulation.Reactors: The insulating layer of the paper covered round wire is processed with an overlapping wrapping technique, giving it strong resistance to short-circuit impact. Its circular cross-section is more suitable for windings.
Rail transit traction motors: The insulating layer of the paper covered round wire has strong adhesion and excellent resistance to vibration and oil contamination. Its conductor, after annealing treatment, has good flexibility, allowing it to adapt to working conditions with frequent start-ups and shutdowns and prolonging the service life of the motor.
| Name | Paper Covered Round Wire |
| Conductor | Copper and Aluminum |
| Dimension | 1.0一7.0mm |
| Insulation materials | Kraft paper/Thermally upgraded kraft paper/Nomex paper/Polyester film/ Polyimide film |
| Insulation Thickness | Single,double or according to your requirement |
| Standard | IEC,NEMA,GB，JIS |
| Packing | 30kg~150kg Ply-woodspool(250*500/250*600) |
| Application | Oil-immersed transformer windings, medium and large electrical motor and power substations, etc. |