The main purpose of the study was to investigate the dielectric strengths of locally produced vegetable oils from Nigerian farms to compare the dielectric strength of the vegetable oil with the mineral oil to see if vegetable oil can be used as an alternative for insulating and cooling of transformers. It was an experimental research. The experimental procedures adopted in carrying out the investigation were sample collection, processing of sample and storing and testing for different properties such as pour point, flash point, peroxide value determination (aging), moisture content, and breakdown voltage test were conducted and results obtained. The findings of the study indicated that vegetable oil has the highest dielectric constant when placed on the same temperature with the mineral oil. One of the recommendations was that owners and managers of electrical transformers should see the urgent need of using vegetable oil as alternative to mineral oil.

Keywords : Transformer, Dielectric Strengths, Vegetable Oil, Mineral Based Oil.