MIDEL Transformer Fluids Selection Guide

MIDEL has been leading the way in the development and deployment of ester-based transformer liquids since the 1970s. Selected by utilities and transformer manufacturers across the globe, MIDEL synthetic and natural ester liquids are acknowledged for their excellent fire safety and environmental protection properties, and their ability to extend the life of transformer cellulose insulation.

Is your transformer a piece of critical equipment? Is it located in a fire or environmentally sensitive location? What would be the consequence of asset failure? MIDEL’s properties drive both installation savings as well as mitigating the risk of damage to life, property and the environment.

Which MIDEL?

The MIDEL family of transformer liquids comprises MIDEL eN 1215, MIDEL eN 1204 and MIDEL 7131. The “eN” prefix denotes natural esters, which are formulated using renewable base oils from different seed crops, whilst MIDEL 7131 is a synthetic ester fluid.

MIDEL eN 1204 is formulated from rapeseed oil. It has a pour point around 13°C lower than the soy-based natural ester - making it a better choice in cooler climates. In common with ALL natural esters on the market, both MIDEL eN 1204 and MIDEL eN 1215 are best suited for use in non free-breathing equipment.

MIDEL 7131 is specifically formulated to be a fire safe, high performance liquid which provides all the benefits of an ester-based liquid, but is also extremely robust. It is the liquid of choice when the performance demands on the transformer fluid are higher, especially if located in a cold climate or when there is a risk of contact with air.

In addition to being suitable and widely used for distribution and power transformers, MIDEL 7131 is also ideal for high temperature, breathing type equipment. It has a long track record in demanding applications such as wind turbines and rolling stock, and is proven up to 433KV.

MIDEL eN 1215 is an alternative natural ester fluid formulated from soybean grown in the USA. This product is a cost effective general purpose liquid, ideally suited to non free-breathing distribution and power transformers for use in temperate climates or indoors. MIDEL eN 1215 is not sold in Australia.

MIDEL 7131, MIDEL eN 1204 and MIDEL eN 1215 are all biodegradable.

Comparing Transformer Fluids

To compare the physical, electrical and chemical properties of the MIDEL transformer fluids, simply download the Selection Guide Table below.