A study of the effect of copper and additives in hydrocarbon and ester based insulating liquids with isothermal microcalorimetry

An isothermal microcalorimeter has been used to study the effect of solid copper in hexadecane, vegetable oil (ester) and mineral oil. The experiments have shown a catalytic effect of copper in oxidation of hydrocarbons and also the anti-oxidative effect of dibenzyl disulphide when combined with copper addition. The catalytic effect of copper is found in hydrocarbon as base oil and hexadecane, but not in experiments using inhibited oil and ester as the dielectric liquid.