Compactness and High-reliability Technology for UHV Circuit-breakers, disconnectors and earthing switches

摘要

UHV circuit breakers (CB) and other switchgears are the highest voltage rating and larger capacity equipment than other ratings, but applying reliable downsizing technology to UHV equipment will improve such advantage factors as environmental performance, safety and cost efficiency. Japanese utilities and manufactures have been positively developing switchgear technologies of "high reliability" and "size reduction". The keys for these technologies are suppressing various incidents of over voltage and finding ways to reduce lightning and switching surges, which CBs generate surge voltage at current interruption on transmission lines and disconnecting switches (DS's) generate very fast transient over voltage (VFTO) at switching. Inserting suitable resistor in the switching process was studied and developed as a solution for the surge voltage suppressing, and has been put to practical use in UHV switchgears. To ensure reliability of power system and its electricity, it is important to clear line fault and restore the system in short time. High speed grounding switch (HSGS) technology has been developed as the solution and able to provide high speed re-closing on UHV system. These technologies have already been field-tested since 1996 in Japan and sufficiently validated. Same technologies are also being adopted to UHV system development in China, where the project is well under way. The high reliable downsizing technologies are expected to apply wider range of applications further.