DIN EN 62271-112:2014-06

This part of DIN EN 62271 standard series applies to alternating current high-speed earthing switches designed for indoor and outdoor applications and for operation at used at service frequencies of 50 Hz and 60 Hz on systems having voltages of 550 kV and above. High-speed earthing switches described in this standard are intended to extinguish the secondary arc remaining after clearings faults on transmission lines by the circuit-breakers. Single-phase or multi-phase auto-reclosing schemes are generally applied for high-voltage transmission systems to enhance system reliability. When an overhead line a fault involving earth occurs, circuit-breakers located at both ends of the line open to clear the fault. In case of high-voltage overhead lines (especially for system voltages equal to or higher than 550 kV), where the conductors are located in the vicinity of each other and transmission systems can be single-phase operated, a low current still flows at the fault point after interruption of the short-circuit current. This current is called secondary arc current. It is caused by the electrostatic coupling with the other adjacent live conductors, and this secondary arc current is difficult to self-extinguish. From a system stability point of view, this leads to a problem since it is preferable that the auto-reclosing scheme operates with a reclosing time of 1 s maximum. To solve this problem, additional measures are necessary to extinguish the secondary arc. Especially for short distance lines without shunt reactors or for double circuit systems with multi-phase auto-reclosing scheme, where 4 legged reactors are not used, one of the useful and important means is to apply a special earthing switch for the purpose of secondary arc extinction. This earthing switch is generally designed for high-speed operation to ensure that the required switching performance is met. Such a device is called high-speed earthing switch (HSES). The responsible body is DKE/UK 432.1 "Hochspannungsschaltgeräte" ("High-voltage switchgear") of the DKE (German Commission for Electrical, Electronic and Information Technologies) at DIN and VDE.