An FEM Based Approach for Detection of Short Circuit Faults In Transformer Windings By Magnetic Field Measurement

Transformers play a major role in the transmission and distribution of power in a power system network. Transformer failures mostly arise from the occurrence of inter turn and inter disc short circuits in the winding. Monitoring the condition of transformers in service deserves significant importance, but face major challenges in identifying minor deformations at early stages. This paper presents the development of a finite element method (FEM) based algorithm for detection and estimation of severity of inter-disc short circuits in the winding by magnetic field measurement around the winding geometry. A two dimensional FEM model of an 11 kV/440 volts transformer is modeled in ANSYS software and short circuits of different percentages are applied at various sections in the disc to simulate the magnetic field distribution around the winding geometry for each case. Analysis on the simulated magnetic field intensity and flux distribution for each case proposes a parameter based on the differences in the magnetic field intensity between regions near symmetrical discs with respect to the center of the winding to be employed for detection of faults and estimation of percentages of inter-disc fault in the winding.