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

The interest for reliable condition monitoring of small-to-medium-power generators has increased in recent years due to the multiple benefits of prompt and decisive fault detection, which minimizes 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. The work is based purely on experimental testing, while a plethora of methods have been explored as to their accuracy to detect and identify the fault, both stationary and dynamically. Finally, the paper proposes a new and non-intrusive method based on monitoring the stray leakage flux and analyses its performance while the generator experiences a deaccelerating transient.