11 Properties of Nomex papers for electrical insulation tasksJohn Moot
For over 50 years, designers and manufacturers of transformers, generators, motors and other electrical equipment have relied on the unique combination of properties in Nomex paper to optimize performance, increase reliability and extend the life of their products. DuPont brand Nomex products offer high electrical, chemical, and mechanical integrity. This makes them ideal for a wide variety of electrical insulation applications, such as: B. Slot insulation, Cover slide, Slot closure and phase insulation in electric motors and generators, layer insulation in transformers and molded parts as housing insulation in other electrical devices.
11 properties distinguish Nomex papers:
- Inherent dielectric strength
- Mechanic solidity
- High temperature resistance
- High chemical compatibility
- High resistance to radiation
- Flame retardancy
- Insensitivity to moisture
- Suitable for low temperatures
- good punchability
- good coatability
- good deformability
Inherent dielectric strength of Nomex papers
At high density, Nomex allows short-term electrical loads of 18 kV / mm to 34 kV / mm (460 V / mil to 870 V / mil), depending on the product type and thickness.
Mechanical strength of Nomex papers
Nomex high-density products have high mechanical toughness, tensile strength and abrasion resistance and are also flexible (with less thickness).
High temperature resistance of Nomex papers
Temperatures up to 200 ° C have little or no effect on the electrical and mechanical properties of Nomex products. The useful properties of Nomex paper are retained even at significantly higher temperatures. These useful properties of Nomex papers are retained for at least 10 years even in continuous operation at temperatures of up to 220 ° C.
High chemical compatibility of Nomex papers
Nomex products are practically not attacked by most solvents and are exceptionally resistant to acids and bases. They are compatible with all classes of paints and adhesives, transformer fluids, lubricating oils and refrigerants. Since Nomex products are not digestible, they are not attacked by insects, fungi or mold.
High radiation resistance of Nomex papers
Nomex paper is practically unaffected by ionizing radiation of 800 MegaGray and retains its useful mechanical and electrical properties even after being exposed to this level of radiation eight times.
Flame resistance of Nomex papers
Nomex products do not cause any toxic reactions in humans or animals. Nomex products do not melt, and with an LOI value of over 20.8 at 220 ° C (the critical value for combustion in normal air) they do not support the combustion process. Nomex products are available that meet the requirements of the Underwriters Laboratories Standard (UL) 94 VO.
Nomex papers are insensitive to moisture
In equilibrium at 95% relative humidity, Nomex papers and high-density particle board retain 90% of their dielectric strength, while many of their mechanical properties are even improved.
Suitable for low temperatures
Nomex products are used in a wide variety of cryogenic applications because of their unique polymer structure. Have at the boiling point of nitrogen (77 K) Nomex 410, Nomex 993 PSB, and Nomex 994 PSB have a tensile strength that is higher than the value at room temperature.
Good punchability of Nomex papers
All Nomex papers and Nomex plates can be used with the usual Punching techniques are processed. The plates can be milled into parts for high-voltage transformers on CNC machining centers.
Good coatability of Nomex papers
Nomex papers can be coated into adhesive tapes with common adhesive systems. Nomex papers can also be coated with epoxy resin systems in order for Prepregs to form.
Good formability of Nomex papers
Nomex can be used to manufacture molded parts for applications in transformers and electric motors.