Aging effect of coconut oil as transformer liquid insulation — Comparison with mineral oil

Coconut oil has been considered as an alternative choice for power transformer liquid insulation. This paper presents ageing aspects of coconut oil in comparison to that of transformer oil. Wet coconut oil and wet and dry transformer oil was aged in sealed and unsealed conditions at 120°C. Variation of color, interfacial tension, acidity, breakdown voltage and frequency dielectric spectroscopy was observed during different aging period of 2, 4, and 7 weeks. In the aging process, the acidity and conductivity levels of coconut oil increased. However, its breakdown strength was considerably high compared to transformer oil showing a possibility of using as a transformer liquid insulation.