Advancing the Reliability of Residual Life Assessment for Turbines through Strain Gauge Measurements: Key Aspects and Latest Developments

Abstract With the need for flexible operation and an aging hydropower fleet, the importance of residual life assessment for turbines has been on the rise. While prediction methods are continuously improving, the most reliable data about the health status of a machine is obtained through measurement campaigns. Unlike fatigue evaluations during the design stage that include safety factors, residual life assessments require higher precision to enable owners to evaluate their assets and investments. The increased precision of a measurement campaign justifies the additional costs incurred. This article emphasizes the significance of a careful review of all aspects, including load history, measurement data, transposition method, and material data. It also presents the latest developments in accordance with IEC 63230 and provides an example prototype measurement to underscore the importance of each aspect. Special attention is given to the transposition of strain data from the measurement location to the hot spot position and its impact on load sequences and stochastic loads. Through a sensitivity study, the article aims to provide a better understanding of the importance of each aspect in the residual life evaluation process.