Wide frequency range analysis of the electromagnetic emissions of electrical machines for diagnosis

The presentation describes the possibilities to evaluate the health of an electrical machine by analyzing its electromagnetic emissions. Different piece of information can be detected according to the frequency range. First of all, a monitoring system sensitive to the degradation of the turn-to-turn insulation quality of the stator winding is presented; it is based on High Frequency emissions. The second part of the presentation is based on the medium and low frequency emissions analysis. It explains how to detect turn-to-turn short circuits in stator windings or in the excitation coils of synchronous machines using the spectrum analysis of the external magnetic field.