Development of a Magnetic Field Measurement Based Scheme for Detection and Localization of Inter-Disc Faults in Transformer Windings by Finite Element Method

Early detection and localization of winding deformation is a major task in ensuring proper condition assessment and maintenance of transformers. This work deals with the formulation of a generalized approach by finite element method (FEM) based analysis on magnetic flux distribution for finding the presence of inter-disc fault and calculation of severity and location of faults in the winding. Artificial short circuits of various severity are created in the simulation model of transformer in ANSYS software which solves the magnetic field intensity and flux density around the winding geometry by finite element method (FEM). The detailed investigation on the simulation results identifies parameters based on the percentage changes in the field intensity and flux density at symmetrical discs in case of short circuits in the winding. The parameters based on the changes in peak values of magnetic field intensity and flux density at symmetrical discs over a cycle identified to be suitable for detection and localization of faults with respect to centre of winding. Moreover, a parameter based on the changes in instantaneous values of flux density at symmetrical discs proves to be suitable for discriminating the faults at upper and lower halves of the winding.