Breakdown Voltage Characteristics of Castor Oil as Alternative to Transformer Insulation Oil

Suitability of non-edible oil as a replacement for mineral oil in power transformer has been a major research concern in product analysis and development. However; there is paucity of information in literature on the suitability of castor oil as alternative transformer insulation oil. This study examined the suitability of castor oil as alternative transformer insulation oil. Four castor oil samples were collected from University of Agriculture; Abeokuta and five experimental tests on alternating current (a.c.) breakdown voltage were carried out on each of the castor oil samples. Temperature range of between 27oC and 37oC was adopted for the study that was carried out in both rainy (July) and dry (December) seasons. A Baur DPA75 was used to measure the a.c. breakdown voltage. The results of a.c. breakdown voltage measurements of castor oil for July at temperatures of 27oC and 32oC were 23.8 kV and 24.2 kV respectively and similar values for December at 30oC and 37oC were 23.9 kV and 24.1 kV respectively. The average breakdown voltage for the two months was 24.0475 kV which is less than 25 kV the minimum standard value for both 11/0.415 kV and 33/0.415 kV transformer insulation oil. This study showed that raw castor oil is not suitable for both 11/0.415 kV and 33/0.415 kV transformer insulation oil.