To increase the profit of large generators, production management seeks to reduce maintenance costs. To achieve this, they are in need of surveillance facilities ever the more précise. On the other hand, ever since eïectric rotating machines exist, operators hâve observed occasion-ally strong currents that may cause damage to the machines. Studies hâve shown that thèse shaft currents generally originate from discrepancies of symmetry. Thèse observations found the basis to conceive a new diagnostic tool relying on shaft voltages, as well as on the phase split currents, neutrals voltages and the flux throught the air gap. Simulations hâve been carried out to détermine the signatures of each failure. To verify the results, we hâve constructed a model which could function with failures such as short-circuits and eccentricities. Comparison between simulated results and measurements hâve proven the tool to be reliable, yet with a potential of improvement. Bearing in mind the simplicity of implementation, its application to production plants is being taken into considération and simulation methods will be given to the French Electricîty Board's research centers, whereas we will continue our research in order to perfect this diagnostic tool.
