Nomex® Insulation Key to SLIM® Wind Turbine Transformer Design

The concept of SLIM® transformers, enabled by the use of DuPont Nomex® as a high-temperature solid insulation, is the result of a collaboration between CG Power Systems and DuPont.  What began in 2000 as an agreement to focus on developing high-temperature, liquid-immersed wind turbine transformers has resulted in the installation by CG Power Systems of more than 6,000 of their SLIM® and Bio-SLIM® transformers worldwide in a variety of market segments. 

Application Description

CG Power Systems, in collaboration with DuPont, developed the compact, reliable SLIM® transformer with high overload capacity.  The use of Nomex®–a high-temperature solid insulation—and silicone—a high-temperature fluid—made this innovative new wind turbine transformer design possible.

As the market evolved, the Bio-SLIM® transformer became the next innovation.  The design of this transformer was based on the existing SLIM type with Nomex® insulation.  To reduce the environmental footprint, CG Power Systems adopted synthetic esters as the dielectric fluid (as per IEC 61099) and optimized the original design to derive maximum benefit from this coolant.

In addition to onshore, near shore and offshore wind energy, SLIM® and 

Bio-SLIM® transformers are used in a number of other markets ranging from oil & gas industries and rail infrastructure to buildings and energy distribution in critical areas.

Some key installations of SLIM® and Bio-SLIM® transformers include:

  • The highest (205 meters) and the largest (7.5 MW) onshore wind turbines in the world (as of 2009).
  • In 2002, CG Power Systems supplied its first SLIM® transformer, rated at 2.5 MVA, for an offshore wind turbine pilot project in Frederikshavn.  Since then, CG Power Systems has grown to become the market leader for wind turbine transformers in offshore wind farms through major turbine manufacturers in Europe.  (Power rating up to 6.2 MVA, as of 2009).
  • Approximately 100 SLIM® and Bio-SLIM® traction transformers were installed in and around Paris to supply electric power to the underground and suburban rail systems operated by RATP, the Paris public transport authority.  

Benefits Gained

Most efficient solution for wind farm offshore platforms:   Despite the severe harshness of the environment, SLIM® and Bio-SLIM® transformers with Nomex® insulation have been proven to provide reliability, fire safety and extended lifetime, with low maintenance requirements.

Compact size:   SLIM® and Bio-SLIM® transformers with Nomex® insulation are smaller and lighter weight at a given power rating than conventional transformers. 

Greater overload capacity:   Nomex® insulation has a proven ability to withstand electrical overloads, an important feature for wind turbine transformers.

Longer service life:   Increased reliability under demanding conditions, combined with improved fire safety and an ability to handle severe overloads, leads to longer service life for SLIM® and Bio-SLIM® transformers with Nomex® insulation.   

Materials Selected and Why

CG Power Systems chose to collaborate with DuPont on this project because of the company’s reputation for innovation, depth of technical expertise and the proven track record of Nomex® insulation technology. 

Working together, CG Power Systems and DuPont maximized the benefits provided by Nomex® solid insulation to make the concept of SLIM® and Bio-SLIM® transformers a reality.  Specifically, the inherent dielectric strength, excellent mechanical toughness and outstanding thermal stability of Nomex® insulation enabled these reliable, compact transformers to be developed.   

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