High voltage transformers form one of the most important links in the transmission and distribution power networks and thus play a vital role in system’s integrity and reliability. Liquid filled transformers use mineral based fluid for insulation of internal parts and for cooling. However, its future availability is forecasted to be scarce. In adition, it is non-biodegradable and poses serious issues for spillage and aquatic life. As a result, research effort started in mid 1990’s to develop fully biodegradable oil due to interest of power utilities. In this context, vegetable-based oils were considered as potential candidates as they are available in plenty as a natural resource, are non-toxic and possess low emission profiles thus making them environmental friendly.. Pakistan is one of the biggest rice growing countries in the world. Quite recently, kitchen grade Rice Bran Oil (RBO) has been introduced in the market. It could prove to be a potential candidate that can be investigated for adoption as an insulating fluid.

With the advent of nano-technology the manufacturers are considering innovation and new technologies initiatives as alternate to conventional materials Several researchers have reported enhancement in the dielectric strength (DS)of insulating oils with the addition of nano-particles. These nano-particles have been used as such or functionalized chemically. However, recent advancement in dielectric-barrier discharge (DBD) has progressed and successfully applied in modification/improvement to the surface of organic/inorganic sheets as well as nano-powders by subjecting them to cold atmospheric plasma discharge (DBD).

In this research project, two locally produced kitchen grade oils such as Corn oil(CO) and RBO beside a non-food grade Jatropha oil were evaluated and compared with the DS of conventional mineral insulating oil (MO) according to IEC 0156. Comparative results revealed excellent performance of RBO as compared to other counterparts. Thus RBO was selected for further property evaluation. TiO2 and SiO2 nano-particles were used to prepare Nano Fluids (NFs). The DS measurements were carried out and results analyzed and shown to conform to Weibull statistical distributions. The results also showed that NFs with SiO2 resulted in increase in DS better than NFs prepared with TiO2.

A DBD reactor was designed and implemented to produce diffuse plasma discharge under high voltage 50Hz electric stress. These nano particles were then functionalized treating them under cold atmospheric plasma discharge in this reactor. These particles were then used to produce plasma treated nano fluids(PNFs). Thse modified nano particles were observed to strongly interact with the liquid molecules rendering better dispersibility. In this case NFs with SiO2 produced more stable fluid than NFs with TiO2 as it resulted in their sedimentation in short time. These results show that the breakdown voltage of RBO with a risk probability of 1% can be improved by 43% while at 10 % the increase is 29% and at 50% the increase is 24 %.These results lead to the conclusion that use of plasma functionalized SiO2 NFs are a suitable choice for application as Transformer oil. The design engineer will not only replace the use of conventional and expensive imported MO but can also reduce the volume of transformer with biodegradable RBO.