THE INFINITELY SMALL AT THE SERVICE OF THE IMMENSELY LARGE

Measuring structural deformation is essential for the safe operation of hydroelectric facilities. This meticulous work on the infinitely small – the installation of strain gauges, followed by the rigorous processing of the data collected – often goes unnoticed. Three examples by way of illustration.

In 2023, following a fracture in the deflectors of a Pelton turbine, protective covers were fitted. A study using strain gauges was carried out to assess the usefulness of the covers and to determine the stresses to which the deflectors are now subjected during start-up phases.

Measurement at 20-bar pressure

Earlier, in 2022, as part of the recommissioning of an overhauled butterfly valve, strain gauge measurements were carried out on the valve and the upstream armouring. The aim was twofold: to compare the results of the FEM calculations, and to determine the clearance between the armouring and the rock. Despite the gauges being submerged and subjected to a pressure of 20 bar, the operation was a success.

Most recently, following suspicion of a certain mode of torsion in the shaft line of a ternary unit, start-up tests using on-board strain gauges were carried out using a telemetry system, enabling data to be analysed in real time.

By deploying this high added-value service, HYDRO’s measurement specialists demonstrate their ability to handle the infinitely small to serve the immensely large.