Multi-Parametric Condition Monitoring of Medium-Power Generators with Brushless Exciters under Mechanical Faults

The interest in reliable condition monitoring of small-to-medium-power generator sets (GenSets) has increased in recent years due to the multiple benefits of prompt and decisive fault detection. This leads to the minimization of catastrophic failures and significantly improves the interconnected load's power reliability. In this paper, the case of mechanical faults is examined and particularly the eccentricity caused by a cocked bearing. The main electrical machine under investigation is a salient pole wound-field synchronous machine (WFSM) with a brushless exciter (BE), which is a very common topology in GenSets. The work is based purely on experimental testing, while a plethora of methods has been assessed based on their accuracy to detect and identify the fault, both stationary and dynamic. Finally, the paper proposes a new and non-intrusive method based on the monitoring of the stray leakage flux and its analysis while the generator experiences a deaccelerating transient, and the role of the exciters's geometrical properties in this new methodology is revealed.