The hydroelectric S. Antonio power plant, featuring a reservoir of 97 million liters of water, was entirely excavated from porphyry rock. Today, it is operated by Eisackwerk Srl, while the monitoring system, provided by SMARTEC, is managed by CESI. The system was specifically designed to monitor penstock deformations at two locations: 860 meters above sea level upstream and 320 meters downstream.
At each of these locations, there are two sections of monitored area, separated by a distance of 2 meters. Each section features 12 strain gauges, 6 longitudinal and 6 circumferential, and 3 temperature sensors. As a result, the vertices of each hexagon are formed by a pair of strain gauges, and the thermometers are positioned on the vertices of a triangle inscribed in the tube’s circumference.
For a more detailed understanding of the system’s geometry and the exact sensor placement, please refer to Figure 2.
All strain and temperature measurements are collected by a data logger installed in a technical room near the power plant.
The monitoring system was set up in two modes to acquire deformation measurements in the following cases:
- Slow deformation phenomena: one measurement per hour
- Fast deformation phenomena: one measurement per second (1 Hz)
The slow mode can be used to analyze phenomena like variations in the reservoir water level and seasonal thermal variations.
The fast ones become necessary for observing mass oscillations and water hammer phenomena.
We found interesting results with this monitoring system, in particular, the 1Hz measurements were compared with water pressure values located at different points of the system.