July 6, 2016

Field experiences with the world’s largest natural ester-filled transformer

Abstract Electric utilities have a duty to supply electricity securely whilst being mindful of environmental needs and fire safety, especially in urban areas. Mineral oil...

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Abstract

Electric utilities have a duty to supply electricity securely whilst being mindful of environmental needs and fire safety, especially in urban areas. Mineral oil in power transformers is the most critical conventional material used. Substituting mineral oil with bio-degradable and renewable liquid such as natural ester, provides a much higher level of safety and sustainability.
This article presents monitoring results for the world’s largest natural ester-filled transformer of advanced design. The results show that thus far, over nearly three years in service, the transformer has been operating perfectly, and that there are absolutely no concerns with the operation of such transformers.

Keywords: natural ester, Envirotemp® FR3®, large power transformer, field results

1. Introduction

Today many regulations are in place demanding from electric utility companies to consider a lot more than just security of supply when expanding the grid. While operators need to ensure technical performance capability, concerns about issues of personal safety and environmental protection are of no less importance. To be able to respond to these requirements, utilities need innovative technologies to equip themselves for the energy supply market of the future.
Sustainable, bio-degradable and renewable – these concepts are the driving force behind the power industry today, with an impact not only on the method of energy generation, but also on the components used. Sparing use of resources and employment of renewable raw materials in place of fossil fuels wherever possible has become a must.

2. Power transformers for new requirements

For power transformers, which are conventional pieces of electric equipment built according to the physics concepts and with materials developed decades ago, it is critical to implement new materials based on renewable resources to achieve sustainability, reliability, and safety.
Another concept gaining importance is the development and installation of electrical equipment able to provide a high level of health and environmental safety and reliability, particularly in regions of great infrastructure density where reducing the risk level has become a major goal.
Insulating oil is the most critical conventional material used in power transformers. As a consequence, the need for achieving a higher level of sustainability and environmental safety has placed focus on natural esters as a substitute for transformer oil. In relation to the increased biodegradability and sustainability requirements, natural ester based fluids are among the most important and widely used alternative liquids.

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