Swept frequency response tests for condition monitoring of power transformers

In 1988, ERA Technology, in collaboration with The Nottingham Trent University, started a detailed program of research for the development of a means of monitoring the condition of a power transformer using the frequency response analysis technique. The research work concentrated on the establishment of a mathematical model of the transformer windings. The models developed were general and accurate. Overall 11 transformers were tested (500kVA - 70MVA). They range from distribution type, arc furnace, power station generator and neutral earthing reactors. In this paper, attention is centred on measuring and predicting the frequency response of iron cored disk-type windings in a 500 kVA distribution type transformer.