Indian Experience in commissioning of World’s first 420kV shunt Reactor with Natural Ester

Mineral oil from petroleum crude has been used in Transformers and Reactors since 1890s. Since inception, manufacturing of mineral oil has gone through several stages of improvement during past 130 years. Further, gas to liquid technology has also been evolved in recent times for mineral oils. Despite the improvement in production technology, Transformer mineral oil suffers from two major disadvantages: lower biodegradability and less fire safety, causing consequential damages during catastrophic failure of Transformers. Further, there are major concerns on the toxic effects of oil spills to nearby environment. Ester based alternate fluids viz. synthetic esters and natural esters mitigate the disadvantages of conventional mineral oil in terms of higher biodegradability and better fire safety. Use of Ester fluids results in less water migration to insulating paper during equilibrium, thereby promoting better insulation dryness and higher equipment life. The experience in India on using alternate environment friendly fluid was till now limited to distribution and medium voltage rating 66 kV class Transformers. Recently, Power Grid Corporation of India Limited (POWERGRID), a major Transmission utility in India took a pilot project to commission world’s first Natural Ester filled 420kV Shunt Reactor to gain field experience.