Óleo vegetal - um substituto do óleo mineral para uso em transformadores: revisão do estado da arte

The importance of the role played by insulating liquids in the good performance of transformers, associated to the increase of environmental concerns, in case of fire, explosion, or possible oil leaks, explains the increased interest in the research about the use of vegetable oils (an earth friendly and fire resistant product), in electrical industry, as substitute of minerals oils. This paper presents the comparison of vegetable oils with mineral oils, in terms of their properties including their influence in the degradation of paper immersed in those oils. It is also presented here, the main advantages of vegetable oils, and the most important improvements that have been recently introduced in such oils, based mainly on experimental research data from laboratory. In spite of the fact that some hundreds of transformers filled with vegetable oils have been working worldwide with good performance, these oils have, until now, a limited use. So, there is a high potential increase for their application, as substitutes of mineral oils, playing the role of electrical insulating, coolant and arc quenching fluid, in electrical transformers, what demands a better knowledge about these fluids. So, the clarification of some doubts, in this field, is one of the main goals of this paper.