ABSTRACT
Risk reduction can be conducted through constructive, technical, organizational or personnel measures. State of the art is to determine the necessary risk reduction, taking into account control dependent protective measures in the sense of functional safety. Complementary protective measures are a special subgroup of protective measures.
Such additional safety functions extend the usual quantified sensor logic actuator chain of safety functions by the operator and the necessary human-machine interface. Standard methods of quantification only apply to the reliability of the technical part of such complementary safety functions. This paper deals with the challenge of taking into account large extent through the human-machine interface. It proposes a systematic approach using a combination of methods offered by standards and literature to determine and quantify the risk reduction of the overall complementary safety instrumented functions. The paper summarizes the proposal of an extension for the assessment of complementary protective functions.
