This paper discusses a novel all-electric control system architecture that uses batteries instead of mechanical springs to provide the required energy for fail-safe valve actuation. To evaluate the reliability of the safety instrumented system, the functional safety principles are explored.
Methods, Procedures, Process:
The paper covers the analysis of functional safety principles when implemented in an all-electric control system. The paper considers the principles of probability of failure on demand (PFD), diagnostic coverage, hardware fault tolerance, component type, and functional safety management as well as the system’s capabilities with regards to these principles.
Results, Observations, Conclusions:
Functional safety and the related safety integrity level (SIL) are based on PFD, systematic capability, and functional safety management. The all-electric control system systematic capability is directly related to the redundancy concept, which can be used for safety, availability, or both. Because of its built-in diagnostics, the system offers an enormous degree of diagnostic coverage. Based on the component failure rates, the PFD can be calculated. The functional safety management requires dedicated activities throughout the development process. This is ensured by independent review personal. Depending on the desired SIL (e.g., SIL3), an independent review of the development ensures the compliance with the functional safety standard IEC 61508.
The paper provides a detailed study of the functional safety principles of, their impact on, and a capability analysis of the all-electric control system.