Research And Developments Of Foundation Fieldbus Safety Instrumented System

Safety is a primary issue in both industrial production and industrial automation field. For a long time, the common way of keeping system safe is using multiple safety protection layers. Because traditional safety instrumented system (SIS) is not in the same layer as process control system, it is certainly that they are independent with each other in application. In general means, safeguard is keeping employees who work in dangerous product regions from harming or death. However, nowadays, safety measures are not limited to assure life safety. Manufactures are improving function performance of equipments at all time to realize both safety and product efficiency. Along with the development of Fieldbus technology and the increase of application in industry, end users hope to integrate the process control system and the safety system. Now fieldbus safety instrumented system has become a new branch of Fieldbus domain.The principle of Fieldbus SIS is the main study object in this thesis. Based on the research of function safety protocol "FF-SIS" which has got the authentication from TUV, the main develop frame and realization project of functional safety instrumented system are mentioned in this thesis too.The topic of research on SIS is elicited by the definition of safety which is at the beginning of this thesis. The major achievements, current advances and trend of SIS are systematically summarized. The advantages of SIS based on fieldbus technology and the current R&D actuality are investigated. The general design way of SIS based on E/E/PE (electrical/electronic/programmable electronic) has been researched, including the methods of risk analysis, risk distribution, validation of safety integrated level and the rules of system configuration, safety logic design and control loop design. The main problems of fieldbus extending to SIS domain can be divided into two aspects "safety communication" and "safety control strategy". Based on the safety communication model and MooN redundancy reliability analysis model, the formula of safety communication residual error calculation has been deduced and the failure probability of MooN (N out of M) redundancy has been calculated too. The software project for FBAP and protocol layer has been designed after researching FF-SIS protocols. According to current grade of R&D, the feasible testing project has been made and the software which was developed has been tested with the designed testcases. Finally, the whole work and prospects of the future are summarized in the paper.