Corrosion Mechanism of UHV Transmission Line Tower Foot in Southern China

Corrosion of tower foot in ultra-high voltage transmission lines is a critical issue for ensuring the safe operation of power grids. Recently, severe corrosion of tower foot has been observed on several UHV transmission lines in southern China, highlighting the emergence of this new problem both domestically and internationally. However, its underlying mechanism remains unclear and requires further investigation. This paper first surveyed the corrosion of on-site tower foot, and obtained comprehensive photographic documentation. The corrosion products at the tower foot were retrieved, and their surface morphology and material composition were analyzed by SEM, EDS, XRD, and XPS. The mechanism and cause of tower foot corrosion were inferred to be the soil corrosion resulting from the deposition of soil and dirty substances on the tower foot. Subsequently, our newly developed soil corrosion monitoring sensor was employed for on-site measurement of soil corrosion rate. It was observed that temperature and moisture exerted significant influence on soil corrosion, with its rate surpassing that of atmospheric corrosion. Therefore, the measurement results of soil corrosion also provided a reasonable explanation for the more severe corrosion observed at the tower foot compared to that at the other part of the tower, thereby offering empirical evidence for understanding the mechanism of soil corrosion at the tower foot. Ultimately, based on this understanding, an effective method for protecting against soil corrosion at the foot of the tower was proposed.