Tesla’s specialist high voltage cable design team has carried out in-situ thermal resistivity testing and CYMCAP modelling for a number of new cable installations recently. For in-situ testing, desktop analysis is used to select locations along a proposed cable route where changes in soil conditions may occur. Measurements are taken on site and samples are retrieved. The samples are laboratory dried and dry-out curves are produced to determine the thermal stability of native soil with variations in moisture content. The thermal resistivity is a key input to the calculation of cable sizing.
Confirmation of the ground conditions is one step in the cable route design process. Our HV cable specialists then provide recommendations on cable sizing, cable configuration and sheath bonding arrangements to achieve the expected MVA capacity. A good understanding of the thermal resistivity of the ground and other trench backfill materials is essential to preventing overheating and premature failure of power cable assets through overloading.