NOMEX paper covered magnet wire uses aramid paper covering to add insulation build, dielectric strength, thermal resistance and mechanical protection. It is commonly considered for transformer, reactor and electrical equipment windings where paper insulation is part of the design.
The wire may use copper or aluminum conductor. The conductor may also have enamel insulation under the paper covering, depending on the voltage, thermal class and customer specification.
What Is NOMEX Paper Covered Magnet Wire?
NOMEX paper covered magnet wire is a winding wire wrapped with aramid paper insulation. The paper layer helps separate turns or layers and can improve dielectric margin. In many designs, the covering works together with varnish, oil, resin or other insulation materials in the final equipment.
For the full material overview, read Magnet Wire Materials.
Key Properties
| Property | Why It Matters |
|---|---|
| Dielectric strength | Paper covering adds insulation distance and supports transformer insulation design. |
| Thermal resistance | Aramid paper is selected for demanding temperature and aging requirements. |
| Mechanical protection | Covering helps protect the conductor and enamel during winding and assembly. |
| System compatibility | Must match oil, varnish, resin and the complete insulation structure. |
Thermal Class
The thermal class depends on the conductor, enamel if used, paper grade, covering construction, impregnation material and equipment insulation system. Always confirm the finished wire standard and end-use approval requirements. Use Enameled Wire Thermal Class Guide for context.
Advantages
- Adds dielectric strength and insulation build.
- Useful in transformers, reactors and large electrical equipment.
- Provides mechanical protection during winding.
- Can be combined with enamel insulation for layered protection.
- Supports designs where paper insulation is part of the system.
Limitations
- Increases finished wire size and reduces winding compactness.
- Wrapping quality, overlap and edge condition must be controlled.
- Material compatibility with oil, resin or varnish must be verified.
- Not usually selected for small compact electronic coils.
Typical Applications
- Power transformers and distribution transformers
- Reactors, chokes and large electromagnetic coils
- Dry-type and oil-filled electrical equipment when compatible
- Windings needing additional layer or turn insulation
- High-reliability equipment with specified paper insulation systems
Testing Requirements
Specify conductor dimensions, covering thickness, overlap, breakdown voltage, dimensional tolerance, thermal aging, flexibility, adhesion if bonded, oil or varnish compatibility and visual inspection for paper defects.
How to Choose NOMEX Paper Covered Wire
Choose NOMEX paper covered wire when dielectric strength, paper insulation design or transformer compatibility is more important than minimum wire size. Compare it with Fiberglass Covered Winding Wire and Kapton Insulated Wire for other covering options.