Effect of antioxidants on critical properties of natural esters for liquid insulations

This work is focused towards identifying alternate insulating medium for replacing the mineral oil. With this aim, investigations are carried out with natural esters based vegetable oils which are considered as environmental friendly and biodegradable products. This work also extends to analyze the properties of vegetable oils with the antioxidants for enhanced insulating medium of transformer applications. The natural esters based vegetable oils such as honge oil, neem oil, mustard oil, punna oil and castor oil are considered as samples for the investigations. The butylated hydroxy toluene, butyalted hydroxy anisole and gallic acid are picked as the investigating antioxidants. Different particle volume fraction ranges from 0% to 1% of antioxidants are included for studying the performance of natural esters. The performances of natural esters without and with antioxidants are examined according to the international standards. From the investigation results, it is found that the natural esters based vegetable oils without and with antioxidants have the potential to replace the mineral oil as the insulating medium in the transformers. The mathematical functions for properties are developed based on the results obtained for various concentration of antioxidant. These functions are used to estimate the intermediate values of properties for different antioxidant concentrations.