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Retrofilling – upgrade your transformer

Retrofilling is the process of replacing mineral oil insulating fluid in an existing transformer with MIDEL fluid. Doing so effectively upgrades the transformer while delivering other demonstrable benefits.

Reasons for retrofilling with MIDEL:

  1. Makes financial sense – get all the benefits of MIDEL without investing in a new transformer
  2. Remove fire risk – the high fire point of MIDEL fluids eliminates the possibility of transformer fire, thereby protecting lives and property plus reinforcing business continuity
  3. Avoid risk of environmental contamination – MIDEL fluids are readily biodegradable, unlike mineral oil which is both toxic and non-biodegradable. Using MIDEL reduces the risk of environmental damage to the environment in case of either minor leak or catastrophic failure of the transformer
  4. Demonstrate Corporate Social Responsibility – retrofilling your transformer with MIDEL shows a commitment to your employees, customers and environment without needing to invest in a new transformer
  5. Recommended by insurance companies – insurance companies, such as FM Global, acknowledge that all transformers are at risk of failure which can result in fire or environmental damage, and can adversely affect business continuity. They regularly advise their clients to retrofill mineral oil transformers with ester fluids, such as MIDEL.
  6. Extend transformer life, delay transformer replacement – using MIDEL will extend transformer life and delay investment in a new replacement transformer. The superior water tolerance properties of MIDEL significantly increase the life of solid insulation, thereby extending the life of the transformer. MIDEL has also been successfully used to enable wet transformers to be brought back into service
  7. Cut operating expenses – maintenance of mineral oil transformers can be costly – consider oil filtration operations and maintenance of fire suppression systems. Using MIDEL can help reduce maintenance OpEx requirements. MIDEL is also much more tolerant of moisture ingress than mineral oil. For areas prone to wet conditions, retrofilling transformers with MIDEL fluids can lead to increased asset reliability
  8. Reduce substation footprint – FM Global guidelines mean MIDEL transformers require significantly less space compared to mineral oil transformers. Using MIDEL enables more than one transformer to be installed in the same footprint required for mineral oil – a compelling solution if new capacity is needed in an existing substation
Retrofilling: Your Questions answered

To find out if your transformer is suitable for retrofilling (certain technical conditions may apply), contact the MIDEL team at

Our global network of MIDEL Service Partners now deliver retrofilling projects across the EMEA, APAC and Americas regions – click here to find out more.