Cross-Bonding Cable Screen — Suppressing Circulating Currents (HV/MV)

An earthing technique for the metallic screens of long single-core high- or medium-voltage cables (IEC 60840, recommended by CIGRE TB 283) in which the screen is not solidly earthed at both ends (which over long runs would generate large circulating currents in the screen due to the voltage induced by the core conductor), but is instead divided into numbered sections with cross-transposition of the screen connections at each section joint, so that the voltages induced in each section largely cancel out over the full cable length. Only the ends of the entire cross-bonded run are solidly earthed; the intermediate screen sections are protected against transient overvoltages by sheath voltage limiters (SVLs).