Fitting Formula of Sheath Currents and Arrangement Optimization of Cables

There will be circulating currents in metal sheaths of cross bonding cables when length or arrangements of three segments are different. The phasor sums of sheath-induced voltages in sheath cross bonding cables are first analyzed. Then, the circulating currents are calculated by EMTP with varied lengths of three segments to get the sample data, which are in turn used to fit out the empirical formula for evaluating sheath circulating currents. Finally, the principle of mixed arrangements is proposed to reduce sheath circulating currents in sheath cross bonding cables when the lengths of cable segments are not equal.