An improved diagnostic system to detect inter-turns short circuits in low voltage stator windings

Abstract

In order to detect stator inter-turns short circuits in low voltage motors, three variables, which can be easily and non-invasively measured, have been experimentally evaluated with an improved methodology: phase current and stray fluxes measured by a commercial probe in front of the motor and by a custom probe on the body of the motor. The analysis of these variables in the frequency domain examines the characteristic harmonics of this fault, already known in the literature. The experimental tests have been carried out on an induction motor which allows to simulate different percentages of short circuit in one phase of its stator winding. The diagnostic information provided by the three variables are consistent among them and with respect to previous researches. The custom probe stands out for its most significant diagnostic content and its low cost, therefore it can be considered as the best candidate for applications in industrial environments.