Development of highly reliable control systems for the gas-insulated switchgear

In recent years, microprocessor - based control, protection and monitoring devices, such as digital relays and diagnostic systems, are applied to electric power fields. The Highly Reliable Control Systems (HRCS) based on microprocessor techniques for the gas - insulated switchgear(G1S) have been developed. From the results of the recent CIGRE circuit breaker reliability survey, the need for improving the reliability of switchgear control circuits is presented. The HRCS for the GIS uses the programmable logic controller(PLC), solid-state electronics and optical sensors as a replacement for conventional hard-wired electromechanical control circuits which improves reliability amd availability of the GIS control circuits. The HRCS has been verified and applied to the substation. This paper introduces the results of verification tests together with the principle of the HRCS. Also reported is application to the high voltage substation.