Production and characterization of electrical transformer insulating fluid from blending Castor and Neem seed oils

Abstract

Castor and neem seed oils were first purified separately through the process of acid degumming, neutralization, bleaching, filtering, washing and drying. The refined castor and neem seed oils was mixed thoroughly at a ratio of 40:60, 50:50 and 60:40 to make up weight of 100g each. The blended ratios were synthesized separately through epoxidation and transesterification reactions to satisfactorily remove glycerol and unsaturation and form an epoxy in the triglycerides of the mixture. The epoxidation process of the triglyceride significantly increased the viscosity whereby making the blended fluids more physically, chemically and thermally balanced. The blended oil esters produced were washed properly with distilled water and dried to purify the esters. The blended epoxy castor-neem oil methyl ester in ratio of 40:60, 50:50 and 60:40 (BEME46, BEME55 and BEME64) were characterized and the following results were obtained: the viscosities of BEME46, BEME55 and BEME64 at a lower temperature of 30°C were 9.30 cSt, 9.45 cSt and 9.48 cSt respectively, while the viscosities at a higher temperature of 70°C were 3.30 cSt, 3.32 cSt and 3.48 cSt respectively, using a glass capillary kinematic viscometer and hot water bath setup. The dielectric strength of BEME46, BEME55 and BEME64 were 30.55 kV, 30.75 kV and 32.02 kV respectively using a megger test set. The acid value or neutralization number of BEME46, BEME55 and BEME64 were 0.1683 mgKOHg-1oil, 0.1405 mgKOHg-1oil and 0.1405 mgKOHg-1oil respectively. The densities were 0.8260 gcm-1, 0.8251 gcm-1 and 0.8219 gcm-1 respectively, while the flash points were 165°C, 168°C and 160°C respectively. BEME46, BEME55 and BEME64 were compared with Transformer Mineral oil obtained from APO Transmission station. It was revealed that the blended oil esters met the transformer standard specifications.