Accurate Detection and Location of Insulation Faults and Free Bulk Deformations in Power

This paper presents a procedure to accurately locate the position of insulation faults and free buckling deformations in the windings of a transformer by using small, simple air-core coils that measure fractions of the machine’s leakage flux. This study is based on four previous works by the same authors, in which the method was successfully applied to low voltage transformers with concentric and disc-type windings and to an 800 kVA oil-immersed machine. In previous research, the possibility of locating the fault was only suggested, and the deformation detection was done by FEM simulation. This paper will present a summary of the fundamentals of the method, and the improved and valid experimental procedure for both the detection of insulation faults and deformations, as well as their localization, in terms of position in the machine windings.