Open IEC 61508 Certification of Products

Abstract

IEC 61508 has been in use for several years since the final parts were released in 2000. Although written from the perspective of a bespoke system, it is more commonly used to certify products for a given SIL level. Valid product certification schemes must involve the assessment of specific product design details as well as an assessment of the safety management system of the product manufacturer and the personnel competency of those professionals involved in the product creation. A proper assessment of a product must completely cover all the requirements of the IEC 61508 standard including the safety management system and build a safety case. The safety case must list each requirement, an argument as to how the product design or its creation process meets the requirement and the necessary evidence to provide reasonable credibility for the argument. This safety case must be available for inspection. Although the safety case typically contains manufacturer proprietary information, those who wish to review the full safety case should be able to do so, perhaps under confidentiality agreement. In addition, an open IEC 61508 certification must include a public certification report that provides an overview of the assessment and the product limitations, if any. This paper describes an assessment technique for product designs and the product development process that produces a full safety case as well as additional public documentation. This “open certification ” method has been used in dozens of instances on product design process. The assessment experiences to date show that most of the problems with conventional methods are solved or at least improved