Safety standards including IEC 61508

The IEC 61508 standard entitled "Functional safety of electrical, electronic, and programmable electronic safety-related systems" provides a basis for the achievement of functional safety. Safety functions are intended to achieve or to maintain a safe state for the equipment under control with respect to a specific hazardous event. Safety requirements are expressed in terms of functions and properties of the product for risk assessment. IEC 61508 is composed of functional safety assessment based from technical requirement, safety management, and personnel competency. Safety integrity is developed to assess the probability of a safety-related system to satisfactorily perform the required safety functions. Safety integrity is considered as a target measure for a safety function allocated to an E/E/PE safety-related system operating in low/high demand of operation. Safety integrity constitutes both systematic safety integrity and hardware safety integrity. Systematic failures arise from incorrect errors in concept, specification, device, manufacture, operation, and maintenance while random hardware failures are developed from degradation mechanisms.