Reliable control system design for contribution to international safety standard, IEC 61508

点击翻译按钮获取中文摘要

Over the past decade the social environment surrounding system safety has changed rapidly. One of the epochs was that TC65 WG9\10 in IEC, International Electrotechnical Commission, established an international standard, IEC 61508. It is applied to almost all electrical/electronic/programmable electronic safety-related systems irrespective of their applications. It has been already quoted into several national standards or guidelines of UK, USA and Japan, including those for process, aerospace and railway transportation sectors. Many studies have simultaneously and independently been made on control system design under possible device failures, reliable control theory, such as integrity, reliable H-infinity control and passive redundancy. The importance of safety function realized in a control system has been growing for the last several years. One of the reasons is that ISO/IEC Guide 51 adopted newly risk for environment and risk for properties as its scope. It is widely known that there are many cases where safety measures outside a control system are not enough to reduce the risk for environment/properties.Hence reliable control theory has been brought to attention by its contribution to system design according to IEC 61508, which can achieve safety function in a control system.This research presents a safety integrity analysis framework for a controller designed especially by reliable control according to the international safety standard, IEC 61508. The presented framework clarifies a concrete contribution of reliable control to required risk reduction and an established meaning of reliable control in system safety design according to IEC 61508. Hence almost all reliable control can be included to the international standard system. The meaning is important beyond measure.