Return voltage measurements of oil impregnated paper insulated transformers

One of the methods currently being investigated as a possible non-intrusive diagnostic tool for condition monitoring of the oil-paper insulation of power transformer is the return voltage measurement (RVM). Using RVM improves the ability to detect the content of water concentration and the ageing process in the oil-paper insulation system and can thus be an indicator of insulation quality and the ageing condition. This paper describes the development of knowledge rules for the interpretation of RVM towards the ageing condition of oil-paper insulation. On the basis of this experiment as well as on the basis of tests on power transformers, knowledge rules are developed to evaluate the ageing condition.