Advanced approach for on-line monitoring of underground power cable environments

This paper describes a new approach to assessment of the thermal environment of underground power cable by daily measurement of soil thermal resistivity and diffusivity along power cable route. It provides superior data to that obtained using traditional methods that use the thermal needle. The technique uses a sphere, which is permanently buried. Constant heat input is applied and the temperature rise over a one and a half-hour period recorded. Using the equation for the transient temperature rise of an ideal spherical source, values of the soil thermal resistivity and diffusivity can be derived. A remote on-line data collection system is also applied to make the monitoring convenient and flexible.