Pongamia oil, an eco-friendly alternative for mineral oil used in high voltage transformers

Pongamia oil natural esters extracted from the seeds of Pongamia Pinnata tree and its derivatives are investigated in this study to assess their suitability for use in high voltage transformers as an insulator and coolant, so as to replace the presently used mineral oil. Higher viscosity of such natural esters poses challenges for the heat transfer and impulse voltage performances, which are thought to be the major drawbacks of their use in high voltage transformers. Reducing the viscosity by chemical methods lowers the fire resistance of these natural esters. In order to obtain natural esters having balanced performance i.e. both lower viscosity and higher fire resistance, blends of Pongamia oil and low viscous fatty acid methyl ester, derived from Pongamia oil by a chemical process called trans-esterification, are prepared and their impulse voltage performance assessed. Preliminary studies conducted on Pongamia oil and its derivatives show that they can be an environmentally friendly and economically viable replacement for mineral oil used in high voltage transformers.