Strategic fault diagnosis approach for hydrogenerator shaft current discharges

Hydroelectric generator shaft current faults, which are mainly due to human error and electromagnetic anomalies in the generator, can cause mechanical bearing failures in several different modes. Because of the silo structure of maintenance departments, such complex failure mechanisms are rarely well diagnosed, and this leads to less-than-optimal maintenance actions because the root causes of the failure are insufficiently understood. This paper proposes a new strategic fault diagnosis approach for shaft current discharges, with the aim of establishing priorities for conducting diagnoses and improving maintenance efficiency. Based on a failure mechanisms review, the authors present a diagnostic strategy for identifying critical shaft currents on hydroelectric generators and also propose a suitable monitoring and decision making methodology to prevent bearing failure using existing sensors and inspections. Some measurement results will be presented.