Optimized design of multiple-supply service trench

Two different standardized trench layouts, containing, gas and water pipelines, telephone cables, 1-kV-and 10-kV-cables (LV and W-cables), so-called multiple-supply service trenches, were analyzed with respect to their thermal loading. In principle two different options were regarded, i.e. with currents in the cables according to VDE 0276 part 1000 and based on the current obtained for the maximal permissible temperature of the cable conductor as determined by the calculation program. The calculations according standard loading conditions resulted for realistic thermal soil conditions (lambda = 1.5Km/W; v(soil) = 15degreesC) in a maximal temperature of the water pipe of 20.1degreesC assuming a water temperature of 18degreesC. In case of the worst conditions i.e. lambda = 1.5Km/W; v(soil) = 20degreesC the maximal temperature for the water pipe will increase up to 21.5degreesC.