A Method for Reducing Dead Time for Single-Phase Reclosing in EHV Transmission

Most faults on transmission lines are single line to ground (SLG). For such faults single-phase reclosing would result in an improvement in transient stability over the alternative of three-phase reclosing. The improvement is offset by the capacitive coupling from the other two energized conductors because it tends to sustain current in the original fault arc path, thereby lengthening the time required for arc deionization. An increase in dead time is therefore required which decreases the net improvement. This paper presents a novel method of nullifying the capacitive coupling effect. The method requires the addition of a capacitor, connected across the terminals of each breaker pole, proportional to the particular line being switched.