January 7, 2019

Circular economy: Stop wasting valuable transformer insulating oil

Used transformer oil (UTO) is a valuable resource because it can be processed to “as new” quality for re-use as insulating fluid. Customers in the...

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Used transformer oil (UTO) is a valuable resource because it can be processed to “as new” quality for re-use as insulating fluid. Customers in the electricity transmission and distribution markets as well as high-energy demanding industries can now take advantage of EOS transformer service offerings ranging from UTO collection to mobile and/or stationary transformer oil regeneration and maintenance. These services are available all over Europe and help companies’ to meet their circular economy requirements and reduce their carbon footprint.

There is limited awareness in many European countries that transformer oil regeneration is a viable process to enhance the oil quality to “as new” condition and extend the overall transformer performance and service life. Tom Larney, Vice President Electrical Oil Services (EOS) confirms: “With a challenging environment of increased demand on utilities and industries to ‘keep the lights on’ in an economic and environmentally friendly manner, within a framework of policies and regulations, asset managers must view recycling and regenerated transformer oil as trusted tools to achieve their objectives. The latest techniques for in-situ oil regeneration to ‘deep cleaning’ insulation systems to extending the life of transformers as well as the option to re-use your own regenerated insulating oils are now both technically and economically viable options for consideration.” Unfortunately, many transformers are old or are poorly maintained. It is however easy to combine a regular four-year mandatory transformer check-up with oil sample testing to check the oil quality and take the appropriate steps if required. In the long term, these actions will save the asset manager money and extend the life of the transformer.

Transformer’s insulation system defines transformer lifetime

It is important to mention that the insulating oil system and specifically the condition of the paper of a transformer determines its performance and service life. A transformer, depending on its performance class, can cost between several thousand up to millions of Euros, and has to provide stable performance over many years. However, the insulating oil degrades over a transformer’s operational lifetime. The oil oxidises upon contact with oxygen, and elevated temperatures further accelerate this process. The formation of acid components or sludge may ultimately lead to a situation where the dielectric or, in extreme cases, the thermal characteristics of the insulating oil are impacted. In the worst-case scenario, the complete transformer may fail, resulting in an outage.

Simple oil sampling ensures well maintained transformers

EOS recommends that the quality of the insulating oil be tested at regular intervals. A good option could be to include the oil testing during one of the mandatory audits. As a first step, this requires the taking of an oil sample, which can expertly be performed by one of the EOS employees traveling to the customer’s premises. This oil sample is then analysed at one of EOS own laboratories. If the analysis shows that the oil quality is insufficient, the experts will advise how to improve the insulating oil quality. Different technological options exist to do this ranging from normal drying, filtering and degassing with an oil-processing unit, on-site regeneration to even an oil change depending on the situation.

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