Liquid immersed transformers have been around for over 120 years. In that time frame, the most common materials used to insulate and cool the transformers have been Kraft paper and pressboard, and mineral oil. They have provided a very reliable system over many years.
The last major new solid insulation materials to reach the market have been thermally upgraded Kraft and Nomex® Brand Paper, introduced in the 1960’s. Since then, little has changed - UNTIL NOW
DuPont has created a new paper insulation ; Nomex® 910 engineered cellulose. It is a three-ply construction, whereby the two plies on the outside of the sheet are a combination of cellulose and Nomex® aramid, uniquely and inherently interwoven. The center ply is 100% cellulose.
These plies are made in the wet form of the sheet, and when meshed together, dried and densified, the final sheet is a single consolidated product. Even high magnification photos cannot distinguish the individual layers.
The interwoven particles of Nomex® are spaced in such a way as to provide thermal protection to the cellulose ingredients, giving it a boost in thermal resistance, not as a chemical additive but as an integral and inherent part of the structure. This cellulose and aramid construction is unique, unlike any previous combination of these two materials.
Thermal performance of Nomex® 910 insulation.
Long term thermal aging tests have been conducted in DuPont laboratories using procedures specified in the latest IEEE Standard for Thermal Aging [IEEE C57.100]. The testing includes the use of sealed tube aging equipment and also dual temperature aging cells.
This type of study is a very long term process, requiring aging at accelerated temperatures for up to 10 to 12 months. The final results are expected to be available in November 2013. Tests are being conducted in the standard mineral oil, and also in other biodegradable fluids.
Based on the preliminary information we have obtained so far, DuPont expects that this new insulation material will have a thermal index of 130oC in mineral oil , which is 10oC greater than thermally upgraded Kraft, the most commonly used insulation in many parts of the world, and a full 20oC higher than standard, untreated Kraft paper. In addition, we project that this material will have a thermal index of at least 140oC in biodegradable fluids.
To view the Nomex® 910 Technical Data Sheet, click here.
For more information about Nomex® 910 please contact:
Connected with Nomex® Help Line
For inquires on product availability and pricing in North America, please contact the Nomex® 610 authorized distributors from DuPont below:
Wrapped Conductor using Nomex® 910:
Rea Wire - (203) 738-6117
Alconex - (800) 443-6481
Coated Nomex® 910 for Layer Insulation:
Bedford Materials - (814) 623-9014
Fabricated Parts Distribution
Xamax - 1- (888)-XAMAX88