Olatunde Ajani Oyelaran, Bukola Olalekan Bolaji, Olusegun David Samuel 307 ASSESSMENT OF CALABASH SEED OIL AS BIOBASED INSULATING FLUID FOR POWER TRANSFORMERS Olatunde Ajani Oyelaran 1 , Bukola Olalekan Bolaji 1 , Olusegun David Samuel 2 ABSTRACT The research on the production of transformer oil from biodegradable oil is the focus of this work. Biobased transformer oil was produced from calabash seed oil. The oil was extracted from the seed, then was purifed using a modifed Dijkstra and Opstal purifcation method. After the produced purifed oil was degummed. The oil charac- teristics obtained are: the density - 0.85 g/cm 3 , boiling point 126°C, specifc gravity 0.813, fash point 164°C, cloud point 10°C, pour point 4°C, pH 5.23, saponifcation value 157 mg KOH/g oil, peroxide value 7.22 meq/g oil, iodine value 52.23 g 100/g oil, free fatty acids 0.072 mg KOH/g oil, acid value 0.142 mg KOH/g oil, kinematic viscosity 8.8 cst, and the dielectric strength 24 kV. The results obtained for the purifed calabash oil meet the requirements of ASTM Standards. It was concluded that the purifed calabash seed oil can be used in place of the conventional transformer oil because it is easily biodegradable and safe for the environment due to its low acid content. Keywords: biobased transformer oil, purifed calabash seed oil, biodegradability. Received 04 September 2018 Accepted 31 May 2019 Journal of Chemical Technology and Metallurgy, 55, 2, 2020, 307-313 1 Department of Mechanical Engineering, Federal University Oye-Ekiti, Nigeria E-mail: ajanioyelaran@gmail.com 2 Department of Mechanical Engineering, Federal University of Petroleum Resources Efurun, Nigeria INTRODUCTION The constant search for sustainable economic de- velopment demands the coherent use of resources and energy, including investment on renewable materials and greener processes [1]. Transformer oil or insulating oil is usually a highly-refned mineral oil that is stable at high temperatures and has excellent electrical insulating prop- erties. It is used in oil-flled transformers, some types of high voltage capacitors, fuorescent lamp ballasts, and some types of high voltage switches and circuit breakers. Its functions are to insulate, suppress corona and arcing, and to serve as a coolant. The oil helps the cooling of the transformer. Because it also provides part of the electrical insulation between internal live parts, the transformer oil must remain stable at high temperatures for an extended period. To improve cooling of large power transformers, the oil-flled tank may have external radiators through which the oil circulates by natural convection. A trans- former is static electronic equipment that transforms voltages and transfers energy via inductive coupling. Inner transformers are flled with insulating oil for heat transfer and insulation [2]. Petroleum-based insulating fuid such as mineral oil is the most commonly used transformer insulating fuid transformers [3]. Mineral oils have been used for over a hundred years in power transformers to ensure electrical insulation and cooling. However, these oils are mainly obtained from petroleum products, a non-renewable resource that involves various political and socio-economic issues. In the last half of the last century, synthetic hydrocarbon fuids, silicone, and ester fuids were introduced, but, at that time, their use was limited [4]. Furthermore, mineral oils are non- biodegradable, high fammable (due its low fash point) and dangerous for the environment, since spills from leaks and equipment failure can contaminate the water and the soil [5 - 7]. Based on the aforementioned, the development of alternative fuids is receiving great attention, in particu- lar vegetable insulating oils, produced from renewable