Considering and comparing safety parameters — Using different calculation approaches of PFD/PFH/HR

Safety standards define the requirements for safety systems, independent of the application. These standards are intended as a basis for the development of advanced safety applications in process, automation or railway market. The purpose of this paper is to describe the differences in how the safety parameters PFD, PFH and HR are calculated in the standards such as IEC/EN 61508, ISA TR84.00.02, IEC 62061 and EN 50129.