Testing MIDEL 7131 and MIDEL 1204 eN

MIDEL 7131 and MIDEL eN have achieved many industry standards to help cement their reputation as consistently high performing fluids. For example, both have been tested in independent laboratories for corrosive sulphur to ASTM D1275 B and IEC 62535 requirements, and were found to be non-corrosive.

Each of the ester-based oils also conforms to the Restriction of Hazardous Substances Directive, with neither containing the flame retardants PBB or PBDE, nor the metals cadmium, lead, mercury and hexavalent chromium.

Dissolved Gas Analysis

Like all transformer oils, Midel ester fluids can be tested during operation in order to spot any possible faults before they become serious. One of the ways this is done is through Dissolved Gas Analysis (DGA), where the identification of key gases and rate of gas production can be used to determine the nature and severity of any problems with your transformer.

Using this form of transformer oil testing allows plenty of time to correct the problem and make any necessary repairs, potentially saving you a lot of time and money. This gives MIDEL 7131 and MIDEL eN a clear advantage over alternatives such as dry-type transformers.

dissolved gas analysis dga with fr3 natural ester

Methods of DGA Interpretation

The data are interpreted in much the same way as for gases in mineral oil. The combustible gases generated by faults in natural ester fluids are similar to those in mineral oil:

  • high levels of hydrogen may be an indication that partial discharge is occurring;

  • carbon oxides in certain ratios suggest overheated paper;

  • hydrocarbon gases could result from a thermal fault in oil; 

  • acetylene points to arcing

Always, the first step is to determine if a fault exists using the amounts and generation rates of dissolved gases before trying to further interpret the gas data.

The most useful approaches to dissolved gases in natural ester fluid use the gas generation rates combined with the IEEE Key Gases method or the IEC Duval method.


Considering ester-filled transformers?

We can help understand the oil testing and analysis requirements.