Transmission lines using aluminium cable steel reinforced ground wires nearby power substations

This article shows the advantages of using transmission lines with ACSR (Aluminium Cable Steel Reinforced) ground wires in the neighbourhood of high voltage power substations. The concept of selfneutralized current is reminded in order to explain why the utilization of a double ACSR ground wire 7-20 km from the transmission line terminal substations is able to reduce up to 65% the value of the terminal substation ground mat current. It is also shown that, for power cables with metallic shielding grounded in both terminal substation ground mats, the reduction of mat current can be as large as 99.5%. The article reminds that these procedures are already successfully used in several high voltage power substations now in operation. Some equivalent circuits are presented in order to allow a simple calculation of the value of the mat current (IM), using ACSR ground wires close to the terminal substations. It is also reminded that Steinmetz Circuit Theory has several advantages over the direct utilization of Maxwell Equations when computing A.C. transmission metallic circuits.