Line fault phenomena and their implications for 3-phase short- and long-line fault clearing

Faults on high voltage overhead lines are recognised to impose onerous transient recovery voltage (TRV) conditions upon the interrupting circuit-breakers and the Standards test the most critical line fault clearing conditions by means of the short-line fault duties. As recent studies have highlighted potentially more severe TRV conditions when clearing three-phase faults, at a long distance, WG A3.19 was established to assess whether these conditions may be regarded as covered by the existing Standards.