This is where natural and synthetic ester fluids, such as MIDEL eN 1204 and MIDEL 7131, are making a real difference.
Unlike large power transformers, distribution transformers are frequently located:
Inside buildings
Near residential areas
In public spaces such as shopping centres, schools, and offices
In these environments, fire safety is critical. At the same time, utilities and operators are under increasing pressure to reduce environmental impact and simplify maintenance.
Traditional mineral oil has served the industry for decades, but it comes with limitations—particularly in fire performance and environmental protection. Ester fluids offer a modern alternative that addresses these concerns.
MIDEL offers both natural and synthetic ester options, allowing engineers to choose the best fit for each application.
Derived from renewable vegetable sources
Ideal for sealed (non-breathing) transformers
Strong environmental credentials
Biodegradable and non-toxic
Suitable for both sealed and breathing transformers
Excellent oxidation stability
Performs well in a wider range of operating conditions
Proven across many demanding applications
This flexibility means transformer designers can balance performance, environment, and operational needs more effectively.
Fire Safety Comes First
One of the biggest advantages of MIDEL ester fluids is their exceptional fire safety.
Both MIDEL eN 1204 and MIDEL 7131 are classified as K-class fluids, meaning they have a high fire point above 300°C (IEC 61039). This significantly reduces the risk of ignition compared to mineral oil.
They also carry trusted industry approvals:
FM Approved less-flammable transformer fluid
UL classified dielectric medium (EOUV)
These certifications mean transformers using MIDEL fluids can often be installed indoors with reduced fire risk, which may also lower the need for complex fire protection systems.