Shaft Voltage and Current Phenomena in Turbo generators: Case Study of Post-Overhauling Bearing Anomaly at a 210 MW KWU Turbine Set: Case Study of Post-Overhauling Bearing Anomaly at a 210 MW KWU Turbine Set

Shaft voltage and bearing currents represent critical reliability challenges for large-scale gubernators. Left unmanaged, these phenomena accelerate bearing degradation, trigger unplanned outages, and compromise machine longevity. This paper investigates the physical mechanisms of shaft voltage generation through a detailed case study of a 210 MW KWU-design turbine following a scheduled overhaul. By correlating electromagnetic, capacitive, magnetic, and electrostatic sources with field observations, this study proposes a robust framework of tiered operational thresholds. Findings indicate that voltages exceeding specific levels, when paired with leakage currents, serve as vital condition-monitoring indicators to prevent catastrophic failure The study demonstrates that voltages above certain level corelated with leakage currents can be an effective tool for condition monitoring, improving reliability and also preventing catastrophic failures. A framework of threshold zones is introduced, and future research recommendations include digital twins, AI-based predictive diagnostics, and advanced materials for grounding brushes. The findings support both immediate operational decision-making and longer-term design improvements for large synchronous machines [1,5&6].