Stator-Interlaminar-Fault Detection Using an External-Flux-Density Sensor

This paper presents the results of a research work devoted to the detection of short circuits between stator laminations of an electrical machine using external magnetic field. The theoretical developments lead one to display the influence of various phenomena on this magnetic field in a wide frequency range. It is shown that surface currents due to burrs at the external surface of the machine have an important contribution compared to the increase of eddy currents in the short-circuit volume. Finally, experimental measurements confirm this theory, and an online method of detection for large generators is proposed.