ABSTRACT
Functional safety is a part of general safety, which depends on the proper response of the control and/or protection systems to the input signals during abnormal states of a machine, installation or hazardous plant. The concept of functional safety formulated in IEC 61508 presents an example of good engineering practice applied to the design and operation of the safety-related electric, electronic and programmable electronic (E/E/PE) systems. The term “safety-related” applies to the systems that perform specified function(s) to ensure that the risk is maintained at acceptable level. Two different requirements should be satisfied to ensure the functional safety:
– the requirements imposed on the performance of safety functions,
– the safety integrity requirements (the probability that the safety functions are performed in a satisfactory way within a specified time).
