Condition monitoring of a retro-filled power transformer by natural ester envirotemp FR3 fluid

Since 1990s, Natural esters have successfully shown best performance and replaced crude base mineral oil as insulation in transformers. Now, the utilities and manufacturer believing in use of natural ester in vast range of transformers due its unique properties. The manufacturer of the natural ester dielectric Envirotemp FR3 fluid reports that no one counts now but still over millions of installations globally. A power transformer installed in KPTCL Bangalore India, retro-filled in Feb 2017 and rated at 66/11 kV 12,5 MVA is excellent example of retro-fill case study. it is fitted with a basic online condition monitoring system that records, temperature, load etc. & periodic check on dissolved gas analysis (DGA), water content in terms of relative saturation, cooling system status; and the temperatures of windings, fluid by thermography. It given us a unique opportunity to study the performance of natural ester Envirotemp FR3 fluid as the dielectric in this power transformer.