Reliability Analysis And Safety Assessment On I/O Module Of Distributed Control System

In a control system, whether it is a basic process control system or a safety instrumented system, process I/O modules are the most widely used and important components, their reliability and security have crucial impact on the reliability and safety of control systems. In this paper, based on the theory of reliability analysis and safety assessment engineering, using the methods of Failure Mode and Effects Analysis(FMEA), Reliability Block Diagram(RBD), Fault Tree Analysis(FTA) and Markov Model, reliability of an analog output module LN-05B is analysed and its Safety Integrity Levels (SIL) under two different work modes, low demand mode and high demand mode, are assessed, respectively. Finally, the paper also proposes a improvement solution for analog output module LN-05B, and the improved module's reliability is analysed and its SIL is assessed to verify that the analogue output module's reliability and safety are improved.