Operations – Poster Presentations
CLEAN CURRENTS 2026
Time: 2:30 PM - 3:30 PM
Day: 9/23/2026
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Details about each presentation and the speakers are below:
In this session:
Mitigating Fatigue Risks in Hydro-Turbines through Rotor-Stator Interaction (RSI) Monitoring
Case of Improper Proximity Sensor Installation Discovered by Shaft Current Monitoring
Mitigating Fatigue Risks in Hydro-Turbines through Rotor-Stator Interaction (RSI) Monitoring (VESKI / Dewesoft)
Presented by Ozren Oreskovic, VESKI, a member of Dewesoft
In hydrogenerator turbines, the passing interactions between the turbine runner (rotating blades) and the guide vanes (stationary blades) generate pressure pulsations due to unsteady flow fields and wake effects, a phenomenon known as rotor-stator interaction (RSI). These pressure fluctuations, if severe, can lead to excessive vibrations, noise, and even fatigue failures in the turbine components, which can significantly influence turbine performance, structural integrity, and maintenance schedules.
RSI often induces increased vibrations and pressure fluctuations at specific frequencies, usually related to blade-passing frequencies. Repeated stress and resonant effects on these frequencies can lead to cracks in the runner blades, runner rings, and labyrinth seals, and can affect other machine parts.
Deploying an online condition monitoring system that simultaneously tracks critical parameters is essential for mitigating the impact of severe rotor-stator interaction (RSI) induced dynamics. An effective system integrates multiple diagnostic techniques, including vibration monitoring, strain gauge measurements, and dynamic pressure sensing, to accurately detect and analyze pressure pulsation-induced vibrations.
Case of Improper Proximity Sensor Installation Discovered by Shaft Current Monitoring (Iris Power - Qualitrol)
Presented by Aaron Doyle, Iris Power - Qualitrol
Company: Hydro Power Plant in Quebec, Canada
Machine: 13.8 kV 83.34 MW 128.6 rpm 56-pole hydro generator rewound in 2024
Summary: A shunt resistor that measures the shaft current was burnt due to high current.
Background: A continuous monitor was installed to measure partial discharge and shaft voltage/current during the outage in 2025. Two sets of carbon brushes and resistive shunts were installed at 90° to each other on top of the turbine bearing to measure the shaft current. The monitor captured an instance of very high shaft current of 83 A peak-to-peak at both current channels. One of the shunt resistors was found to be burnt one day later.
Findings and Confirmation: A proximity sensor was improperly installed at the upper guide bearing. It was in contact with the shaft and was not insulated. This formed a current loop with the shaft and therefore caused a high current as well as occasional sparking. The high current has not been recorded again by the monitor after the sensor was removed.
Takeaway: Shaft voltage and current can be caused by multiple anomalies and faults in the generator. In this case, apart from uninsulated bearings, localized current loops along the shaft can be formed by some not so obvious ways.
Sponsored by:
