Southern Mapping Company has been providing solutions to the power supply industry since 1997, when it first began surveying new and existing power line routes for Eskom. In 2013, an Eskom partner approached the company with a problem regarding a power line in the Cape.
Eskom needed to communicate between two substations and wanted to place a fibre optic cable on the 56 km power line to achieve this. To engineer a solution, accurate knowledge of the position or sag length of the conductors and the earth wires, the power flow through the line as well as the conductor temperature was required.
To measure the conductor geometry in a useful manner, the entire line needed to be surveyed under the same ambient and power load conditions. This was achieved by flying a Lidar survey of the line, as rapidly as possible, at a time of day when the weather conditions were relatively stable, while the power flow through the line was held constant. As the power line crossed some of the highest mountains in the Cape, a variety of weather conditions were expected and the terrain rose steeply from the inland side of the mountains (540 m over 33 km) and then dropped even more rapidly (900 m over 23 km) from the highest point of the line to the substation in the valley below.