Nomex 900 group

DuPont™ Nomex® 900 line of liquid immersed transformers

Specially designed for liquid-immersed transformers, the DuPont™ Nomex® 900 line is an ideal insulation solution that helps achieve higher short and long-term reliability or reduction in size and weight with greater power density.

Insulation systems based on Nomex® 900 Series papers and pressboards help maintain excellent electrical and mechanical properties throughout the life of a liquid-immersed transformer.

Insulation systems based on the Nomex® 900 Series can reduce the weight of a liquid-immersed transformer by up to 25% for the same kVA output. Conversely, the kVA rating can be increased by up to 50% for the same size and weight.

The Nomex® 900 Series is compatible with common adhesives, transformer oils and dielectric fluids, including high temperature fluids such as silicone oils and ester fluids, allowing for even greater size and weight savings.

Nomex® 910

Nomex® 910 is a unique aramid-reinforced cellulosic material made from high-quality electrical grade pulp and the same heat-resistant meta-aramid polymer binder as other Nomex® papers. The paper consists of a single compacted sheet with no additional binders or additives.

Its physical and electrical properties are intermediate between those of Nomex® 410 and cellulose paper. It can therefore be used to optimize transformer design in terms of cost, operating temperatures or extending the life of the insulation system.

Based on thermal aging (IEEE C57.100™-2001), the thermal performance of Nomex® 910 is at least 20°C better than standard kraft paper in petroleum systems. This performance improvement results in a system thermal rating of 130°C in mineral oil and 140°C in natural ester fluids.

A comparison of the voltage test results in mineral oil (ASTM D149) shows that the new paper has over 30% higher AC withstand voltage than kraft paper. This could prove to be an advantage in transformer winding design, with potential savings in multilayer insulation structures.

Applications for Nomex® 910 include interlayer insulation in liquid-immersed distribution and lower-power transformers, and wire-wrapping of conductors in medium and large-scale transformer design.

Nomex® 910 will initially be offered in three thicknesses – 0,08 mm (3 mil), 0,13 mm (5 mil) and 0,18 mm (7 mil). Additional thicknesses may be offered in the future.

Nomex® 926

Nomex® 926 is a strong, high dielectric strength, high temperature, extremely tough and chemically stable paper specifically designed for use as cable protection in liquid immersed transformers. The excellent impregnability of Nomex® 926 improves its electrical properties in oil. Nomex® 926 offers exceptional shrink and pressure resistance.

The product is ideal for applications with high loads. It is suitable for all high-temperature applications defined in IEEE C57.154, with an upper thermal class limit of 180 °C.

Nomex® 926 is only available in 0,05 mm (2 mil) thickness.

Nomex® 992 PSB

Nomex® 992 PSB is a low density pressboard produced in two gauges (1,6mm and 3,2mm) with a specific gravity of 0,5. The low density of Nomex® 992 PSB simplifies molding of complex geometries and delivers the highest saturability of Nomex® pressboard products.

One of the common applications for Nomex® 992 PSB is in transformer core tubes.

Nomex® 993 PSB

Nomex® 993 PSB is a medium density pressboard produced in gauges from 1,0 mm (40 mil) to 4,0 mm (160 mil) with a specific gravity of 0,7 to 0,9. Nomex® 993 PSB delivers a balance of stability and ductility, outstanding saturability and excellent in-oil properties.

Nomex® 993 PSB is excellent for liquid immersed transformer applications where a larger molded part is required, e.g. B. shroud rings, dielectric barriers or core tubes in larger transformer designs.

Nomex® 994 PSB

Nomex® 994 PSB is a high density pressboard produced in gauges from 1,0 mm (40 mil) to 9,6 mm (380 mil) with a specific gravity of 1,1 to 1,2. Nomex® 994 PSB provides outstanding stability under compressive loads. The excellent resilience helps ensure that the coil structures remain taut and can withstand short circuit forces - even after years of use.

It absorbs oil and other liquids, but not as readily as Nomex® 992 PSB and Nomex® 993 PSB.

Nomex® 994 PSB is typically used for spacers and other structural components in liquid immersed transformers.

Typical applications in liquid immersed transformers for the Nomex® 900 series

• Mobile Transformers
• traction transformers
• Wind Turbine Generator Transformers (GSU)
• rectifier transformers
• furnace transformers
• Distribution Transformers (<36 kV)
• Power Transformers (>36 kV)
• rail transformers
• HVDC Transformers/Reactors
• Underground/Underwater Transformers

Nomex is the insulating material of choice for almost all electrical engineering applications. We process every Nomex variant into ready-to-install insulating partsn.