Alternative liquid dielectrics in power transformer insulation: a review

Transformer liquid dielectrics evolved where mineral oil has been the dominant choice until emergence of synthetic esters and natural esters. Natural ester-based oils have under extensive investigations to enhance their properties for replacing petroleum-based oil, which is non-biodegradable poor dielectric properties. This paper focuses on exposition ester application in mixed transformer dielectrics. Physical, chemical, electrical, ageing characteristics these dissolved gas analysis (DGA) were reviewed. Physical include viscosity, pour point, flash fire point are vital indicators heat insulation risk. Chemical considered water content, acid number, DGA, corrosive sulphur, sludge content limit detect degradation corrosion due ageing. Electrical including breakdown voltage consistent during overload fault conditions. These evolving alternative reviewed based ASTM International standards Electro technical Commission acceptable review was compiled avail modern methodologies both industry scholars, also providing significance using power transformers as they concluded show superiority over non-mixed