Extend life or increase overload capacity with standardized high temperature capability.

Transformer designs are constrained by the thermal class of the solid insulation system. Commonly regarded as the ‘weak link’ in the expected life of the transformer, the aging of the insulating paper (predominantly designed with cellulose or thermally upgraded Kraft (TUK) cellulose) is directly impacted by its interaction with the dielectric coolant and the operating temperature of the transformer. And, there have been no significant mainstream technical developments in this area since the introduction and standardization of TUK in the 1960s.

International standards that guide the design of transformers throughout industry have subsequently been written to accommodate a 95°C or 110°C hot spot, with 55°C or 65°C average winding rise (AWR), for cellulose and TUK, respectively, to define transformer unit life expectancy (defined as 20.55 years by the IEEE loading guide).

But, now, this constraint has been lifted.  And, the industry has standardized new higher temperature capabilities (to accommodate a 15°C or 20°C increase in hot spot) enabling you to get more out of your transformer – whether that’s additional load capability, extended asset life, or reduced transformer footprint.

Many OEMs and utilities around the globe are using FR3 fluid and taking advantaging of its (internationally standardized) high temperature capability to:

  • Save on initial costs without sacrificing reliability
  • Redesign transformers with a smaller footprint yet maintain load capacity and reliability
  • Use same size transformers yet increase load capacity by up to 20% with the same life expectancy


High Temperature Insulation Advantage

As validated by international standard accelerated testing methods, an insulating system with Envirotemp™ FR3™ fluid can operate up to 20°C warmer (than mineral oil equivalent) while maintaining the same life or extended life expectation. Or, utilities can increase their overload capacity by up to 20%. In many cases, utilities choose to do both – design their transformers to run at 120°C to gain overload capacity and still extend their asset life.

Furthermore, this capability enables the design of new transformers to require “less cooling” – up to 20°C less cooling – which results in more cost effective transformers. These smaller transformers could use less fluid and construction materials while delivering the same or increased load capacity.

The high temperature insulation advantage works for both new and retrofilled power and distribution transformers.

Contact our dielectric fluids team to help you incorporate these cost-saving, performance-enhancing solutions into your grid.



See  IEC 60076-14 or IEEE C57.154 Standard for the Design, Testing, and Application of Liquid-Immersed Distribution, Power, and Regulating Transformers Using High-Temperature Insulation Systems and Operating at Elevated Temperature. Published October 30, 2012.