Abstract:
Mineral insulating oils have traditionally been used as insulating liquids in oil filled electrical equipment such as transformers since 1900’s. They serve as coolants and dielectrics. These oils are however environmentally toxic and inflammable. They require costly fire protection schemes and deluge systems. Increasing awareness of fire safety and environmental protection has also led to a corresponding increasing trend of substituting mineral insulating oil with natural, environmentally friendly, plant-based oils (natural esters). The increase in power rating of transformers also calls for high temperature performance insulating oils. It has been noted that plant based dielectric fluids are better than mineral insulation oils in many technical aspects. Plant based insulating oils are non-toxic, and possess higher fire points and excellent biodegradability characteristics. Thus, in order to reduce the hazardous environmental impact and to improve the fire safety of transformers, there is an increasing need for plant based insulating liquids as transformer insulating oils. This thesis presents results of series of experiments that were performed to investigate the electrical, thermal, physical and chemical properties of food grade Persea americana oil (PAO). For comparison, the corresponding properties of mineral insulation oil (MIO) in the same experimental conditions were also measured and compared with those of PAO. In this investigation, two different types of Persea americana oil samples consisting of extra virgin and refined PAO were tested. The results obtained show that the average electrical, thermal, physical and chemical properties of PAO meet the IEC and IEEE specifications for new natural liquid insulation oils. This confirms that Persea americana oil can be used as an alternative transformer liquid insulation.
