A Simple Method for Evaluating Ground-Fault Current Transfer at the Transition Station of a Combined Overhead-Cable Line

When a substation is fed by a combined overheadcabletransmission line, a significant part of the ground fault currentflows through cable sheaths and is discharged into the soil atthe transition station where cables are connected to the overheadline. Such a phenomenon, known as “fault application transfer,”may result in high ground potentials at the transition station whichmay cause shocks and equipment damage. The scope of this paperis to present new analytic formulas which can be used for the directcalculation of the fault current transferred at the transitionstation and its ground potential rise as well as the substation earthcurrent. The proposed formulas allow evaluating the influence ofthe main factors to the fault application transfer phenomenon andcan be employed, at the preliminary design stage, to easily assessthe most appropriate safety conditions to avoid dangerous effects.