Abstract: Reliability has been the important index for DCS (Distributed Control System). A safe and reliable control system can reduce unexpected shutdown during normal processing, improve production quality, lower maintenance cost and reduce investment risk. It shall be considered how to evaluate and improve reliability of DCS during system design. As a subject for science, reliability engineering has developed many analysis technologies, which is helpful to find system status when elements are failure. How to evaluate and analyze DCS reliability by the method of quantitative analysis is mainly introduced in this article.

摘要： DCS（分散型控制系统）的可靠性已经成为系统设计的重要指标，一个安全可靠的控制系统不仅能减少生产过程中的非正常停工次数，还能提高产品质量、减少维修成本、降低投资风险。如何评价和提高DCS的可靠性，是系统设计时必须考虑的问题。可靠性工程作为一门学科已经发展出了丰富的定量分析技术，这些技术有助于了解和分析元件失效情况下系统的工作情况。本文重点介绍如何采用定量分析的方法评估和分析DCS的可靠性。

关键词: 分散型控制系统, 可靠性, 平均失效时间, 平均故障修复时间, 失效率, 诊断覆盖率, Distributed Control System, Reliability, Mean Time to Failure, Mean Time to Repair, Failure Rate, Diagnostic coverage