Effect of electrical discharge on the properties of natural esters

Vegetable-based insulating oils have been an alternative to mineral insulating oil for oil-immersed transformers due to concern on less flammable, environmental-friendly, biodegradable, and sustainable resources of petroleum-based mineral insulating oil. This paper presents the effect of electrical discharges on the properties (acidity, water content, and breakdown voltage) of two varieties of vegetable-based insulating oils (1) natural ester and (2) low viscosity insulating fluids derived from a natural ester. To investigated the effect of electrical discharges, 200 up to 1000 discharges are applied on both oils under 50 Hz inhomogeneous electric field. Results indicate that the low viscosity insulating fluids derived from natural ester tend to maintain their properties compared to natural ester.