Experimental study on vegetable oils properties for power transformer

One of the most important equipment in electrical power system is transformer. Most of transformers are using oil as the cooling medium and commonly use petroleum based oil. The reason of choosing petroleum based oil as transformer oil because it has a good dielectric strength and cooling performance. However, the usage of mineral oil has affected the environment as its non-biodegradability property and non-renewable resource. Therefore, renewable resource like vegetable oil is chosen as an alternative to replace mineral oil for transformer insulation liquid. In this paper, palm oil, coconut oil and virgin coconut oil are tested in a single-phase step down transformer that use 220 V supply and 50 Hz frequency with a load 110 V induction motor. Then, those vegetable oils are taken to undergo oil measurement experiments such breakdown voltage test, moisture content test and viscosity test. Before and after application of oils into power transformer are compared and it shows that virgin coconut oil has the highest breakdown voltage, lowest moisture content and also lowest viscosity, which are very good. It can be said that virgin coconut oil is better than palm oil and coconut oil.