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Retrofilling Services

MIDEL Ester Fluid For Your Transformer

To extend our breadth of services and better serve our customers, we are pleased to announce that we have become an official MIDEL Service Partner in Singapore. Our technical team successfully completed a technical training course, and we are now ready to deliver transformer retrofilling throughout our operational area.

Retrofilling (replacing mineral oil insulating fluid in a transformer with MIDEL ester fluid) is a proven process, first performed in the 1970s. When the process is performed by a MIDEL Service Partner, outages are kept to a minimum, and the work is performed in-situ.

The result is an upgraded transformer with greatly improved fire safety and environmental protection credentials. In brief, MIDEL ester fluid outperforms mineral oil in the following key areas:

  • MIDEL dielectric ester fluids are K-class, meaning they have a fire point of > 300°C (compared to mineral oil’s fire point of 170°C)
  • All MIDEL fluids are classified as readily/fully biodegradable. Mineral oil is not biodegradable.
  • MIDEL ester fluids are highly moisture tolerant and can extend the life of the transformer’s cellulose insulation.
  • A key advantage of using MIDEL fluids is the ability to run a transformer at a higher temperature, giving operators the ability to get more power out, without increasing the size and weight of the unit.

Esters as dielectric fluids for transformer cooling

The advantages of submerging transformer coils in a dielectric fluid are aplenty. With such a fluid, it lets designers lessen electrical clearers and significant enhance cooling performance, hence, enabling transformers to be more compact. For many years, mineral oil has been used in electrical transformers due to its electrical and cooling performance.  However, mineral oil has several shortcomings that include poor environmental performance, potential flammability, corrosive sulphur, and low moisture tolerance.

To solve these issues, it would be ideal to use ester-based fluids as they don’t contain corrosive sulphur compounds, are readily biodegradable, fire-safe, and boast exceptional dielectric characteristics. Additionally, ester fluids have also been known to lengthen the lifespan of cellulose insulation, bringing additional benefits to operators.

Transformer ester fluids can be separated into two categories – synthetic and natural.

Synthetic esters are produced from meticulously chosen raw materials to come up with a completed product which is robust and utilised globally in power and distribution transformers (in sealed and breathing units). It’s known to be a high-performing fluid that is ideal for usage in every kind of transformer applications. Critically, MIDEL 7131 has exceptional oxidation stability and a significantly low pour point, making it ideal for breathing systems and cold climates in which the fluid is exposed from the air.

Natural esters are created from sustainable natural sources, for instance, MIDEL eN 1215 (soybean) and MIDEL eN 1204 (canola/rapeseed). In order to ensure the most ideal fit for the application, the base oil is selected carefully; but unlike synthetic ester fluids, it’s not possible for the attributes of such base oils to be significantly changed. Hence, for a natural ester dielectric fluid to be obtained which stays at a liquid state at low temperatures, a middle ground needs to be found, and usually, a base oil with lowered oxidation stability is selected. Correspondingly, it’s only recommended for natural esters to be used for sealed machinery. For a quick reference, the MIDEL range of transformer ester fluids consist of a few relative pour points that’ll be useful for one to note, and they are:

  • MIDEL eN 1215 (soybean): -18°C
  • MIDEL eN 1204 (rapeseed/canola): -31°C
  • MIDEL 7131: -56°C

Reasons for Retrofilling

It is known as a procedure for replacing mineral oil insulating fluid in an existing transformer filled with MIDEL ester fluid. As such, this will upgrade the transformer as well as provide other sorts of apparent advantages.

Eliminates fire risk – MIDEL fluids have a high fire point which removes the likelihood of transformer fire, henceforth, safeguarding properties and lives, fortifying business continuity.

Makes financial sense – without getting a new transformer, you can still enjoy the numerous benefits that MIDEL provides.

Prevent environmental contamination from occurring – easily biodegradable, MIDEL fluids are a lot more ideal for the environment unlike mineral oil as it is non-biodegradable. With MIDEL, it lowers the risk of causing harm to the environment due to a minor leak or transformer failure.

Recommended by insurance companies – FM Global, for instance, is one of the many insurance companies that are well-aware that transformers may potentially break down and lead to environmental damage or a fire, as such, may adversely impact business continuity. Hence, they constantly advise their clients to use MIDEL fluids when retrofilling mineral oil transformers.

Showcase Corporate Social Responsibility (CSR) – demonstrate dedication towards your customers, employees in Singapore, and the environment by retrofilling your transformer using MIDEL ester fluid without having to purchase a new transformer.

Lower operational costs – as servicing mineral oil transformer can be expensive, MIDEL is able to assist by lessening the maintenance OpEx requirements. Compared to mineral oil, MIDEL is a lot more tolerant of moisture ingress. For certain areas that are more susceptible to wet conditions, using MIDEL fluids to retrofill transformers will lead to improved asset reliability.

Extend transformer lifespan, delay its replacement – with MIDEL fluids, it will enhance transformer life and delay transformer replacement. The exceptional water tolerance properties of MIDEL fluids enhance the life of solid insulation significantly, therefore lengthening the transformer’s lifespan. Using MIDEL, it has also been possible for wet transformers to resume operations.

Lower substation footprint – according to FM Global guidelines, MIDEL transformers need much lesser space in comparison to mineral oil transformers. With MIDEL, it allows more than a single transformer’s installation to happen in the same footprint needed for mineral oil – an excellent solution if new capacity is required in an existing substation.



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