End-winding vibration monitoring: Pivotal in preventing major damage on a large turbo-generator

End-winding vibration issues have been an ever increasing subject of interest in the industry, specifically in the past decade. Increasing numbers of major failures due mostly to insulation breakdown have been directly attributed to end-winding vibration. The importance of monitoring this phenomenon has become quite clear to the industry in order to prevent these failures, correct ineffective end-winding support structures and closely monitor the performance of the Unit under normal operating conditions. The introduction of fiber-optic technology has allowed the industry to begin understanding this problem using real data recorded on actual operating Units, instead of relying on models, design estimates and/or visual observations during outages. Finally, the use of on-line monitoring systems allow the utilities the opportunity to rely on precise data; vibration data along with temperature data, active/reactive power and other operating parameters, to produce a complete picture of the Unit´s performance while the Unit goes through various operating conditions. The case study included in this paper will show quite clearly how this technology can be very effective in the monitoring, detection and identification of problems emanating from electro-magnetic stresses exerted on the end-winding structure, as well as the insulation. Serious issues with the insulation occurred at this nuclear power plant located in China and the monitoring system installed was instrumental in helping the utility properly detect the problem and thus; preventing additional serious damage to the end-windings.