Rape seed oil derivative as a new capacitor impregnant

There is a growing demand for nontoxic, biodegradable low flammability fluid to replace toxic, non biodegradable polychlorinated biphenyls (PCB´s) and fluids based on fast depleting petroleum crudes. In this search a number of synthetic compounds viz., esters, silicones, fluorocarbons have been developed and have reached various stages of evaluation and commercialisation. In this context exhaustive investigations were carried out in CPRI on rape seed oil of vegetable origin as India is one of the major producers of rape seeds and ranks third in the world next to China and Canada. The rape seed oil is a triglyceride of a mixture of long chain fatty acids-erucic acid, oleic acid and linoleic acids. The triglyceride ester has been converted to simple methyl ester by trans-esterification process using a catalyst and methanol. The evaluation of the methyl ester of rape seed oil (MRSO) has been done in comparison to commercially available capacitor fluids Midel, Baylectrol, PCB and found to be comparable. This paper highlights an attempt to use vegetable based MRSO as capacitor impregnant and also covers the studies made on two coupling capacitors impregnated with MRSO. These capacitors have been evaluated as per IEC 358. This has led to the development of MRSO as a possible alternative fluid for capacitor impregnation