Assessment of Jatropha Oil as Insulating Fluid for Power Transformers

ABSTRACT

Seed-based oil has been identified as a viable alternative insulating fluid and a number of vegetable oils has been studied for that purpose. Among the seed-based oils studied is Jatropha oil which was reported to have suitable breakdown strength for high voltage application. However, most of the reports did not study the ageing characteristics of the oil and its compatibility with cellulose insulation. In this present study, the properties and ageing behaviour of a freshly prepared Jatropha oil and its compatibility with cellulose insulation paper were evaluated. The oil was purified through modified Dijkstra and Opstal purification method. The thermo‑physical and dielectric studies of the oil was performed and thermal ageing of Kraft paper in the prepared ester fluid was performed. Thermally accelerated ageing was performed with an open beaker containing ageing catalysts, thermally upgraded insulation paper, and the fluid at 140°C for 120, 240, 360 and 480 h. Jatropha oil is a high temperature fluid with high specific heat capacity of 2.59 kJ kg−1 K and low dielectric loss of 0.009. The oil became polymerised with ageing in open cup. This may be due to thermo‑oxidative degradation of the oil that progressed with ageing time. This is an indication that the oil is not suitable for use in free breathing power equipment.

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