ABB Halle Uses Nomex® Insulation for Transformer Retrofit

A transformer retrofit with DuPont™ Nomex® brand paper helped improve the flexibility and reliability of a liquid-immersed unit at a hydroelectric power plant in which the original insulating cellulosic paper and oil had degenerated to a considerable degree due to aging.  This transformer retrofit also reduced maintenance costs.

Application Description 

Engineers from ABB Halle, a world leader in transformer design, manufacture, retrofit and repair, performed a condition assessment on a transformer in a hydroelectric power plant and determined the need for a transformer retrofit.

ABB Halle’s transformer retrofit experts used a hybrid insulation system with Nomex® paper and cellulosic pressboard.  They modernized the liquid-immersed 6.3 MVA (21 kV/6.3 kV) Trafo Union unit manufactured in 1982 by wrapping the conductors with Nomex® paper.

Benefits Gained

Improved operational flexibility:   The use of Nomex® paper as protective insulation of the conductors enables higher overload capacity.

Enhanced reliability:   This transformer retrofit with Nomex® paper enabled the rating to be upgraded from 6.3 MVA to 7 MVA, resulting in enhanced reliability under demanding operating conditions.

Reduced maintenance costs:   Less maintenance will be required because Nomex® insulation shows negligibly low thermal aging over extended working lifetimes, resulting in significant improvement in oil quality.

Extended service life:   Increased reliability under demanding conditions, combined with greater overload capacity and lower losses, and may lead to longer service life.

Materials Selected and Why

Nomex® paper was selected as the insulation for the conductors due to its inherent dielectric strength, ability to withstand electrical loads, excellent mechanical toughness and negligible aging over a long service life.

Retrofit with DuPont™ Nomex® Boosts Transformer Flexibility and Reliability, Lowers Maintenance Costs