The methods of liquidation single-phase short circuit in the aerial lines of extra-high voltage
For interconnected system it is extremely important to promote a fast elimination of the single line to ground fault. The most used suppression method is the fast single-phase auto-reclosing (SPAR). In this maneuver only the faulty phase is opened at both ends, resulting in a minimum disturbance for the system that is still connected through the other two healthy phases. For EHV lines more than 70 % of SLG faults are non-permanent (transient or unstable), or better, can self-extinguish. These faults can be eliminated during dead time with the subsequent system restoration to normal condition. Thus, SPAR results in the main procedure to enhance EHV transmission systems reliability. SPAR success through the elimination of secondary arc is defined by the characteristic of the secondary arc elongation in long gaps, and also, the efficient mitigation methods to reduce secondary arc current (SAC) and, after secondary arc extinction, the recovery voltage (RV). The secondary arc is maintained through capacitive and inductive coupling of faulty opened phase and the healthy phases during SPAR. Besides, if the line is shunt compensated the opened phase will be physically connected to energized circuit through four-legged shunt reactor. The most important parameters associated to secondary arc extinction are: SAC flowing in arc before its extinction; RV appearing across the secondary arc path after secondary arc extinction.