What is Single Failure Criterion

The requirements for safety important instrumentation and control (I&C) systems, their components (software and hardware complexes, equipment), and processes of their development are provided. The reliability of I&C systems and their components are ensured by the requirements for prevention and protection against common cause failures, compliance with the single failure and redundancy criteria, and prevention of human errors. The requirements for operational stability of the components cover resistance to environmental impacts, mechanical (including seismic) and other external impacts, and insensitivity to changes in power supply parameters and electromagnetic interference. Requirements for the performance quality include characteristics pertaining to the accuracy and performance time of functions. Requirements for independence ensure that the system remains operable if its components fail and that the effects of electromagnetic radiation, fires, breakdown of insulation, and leaks in cables are minimized.