Surge Current Withstand Capability of Natural Ester Oil: A Comparison to Gas-to-Liquid Transformer Oil

The basic electrical characteristics of a natural ester oil are experimentally investigated and compared to gas-to-liquid transformer oil with emphasis given to the endurance against surge events. An accelerated degradation test is conducted using a sequence of current impulses generated through a combination wave generator. This test is employed to investigate changes in the electrical conductivity of the oil, serving as a crucial performance indicator for assessing its surge current withstand capability. Experimental results on the surge degradation of the natural ester oil are compared to those of gas-to-liquid oil, which is commonly used in power transformers. A discussion is made on the possible use of natural ester oils as a liquid matrix for environmentally friendly surge-proof nanofluids to substitute transformer oils, which are commonly employed as insulating liquids and coolants in the power industry.