ISO 13849-1 is the most important standard for regulating the basic principles and performance required of a safety control systems for machines and devices. This standard was greatly revised in November 2006. This revision is expected to cause major changes in the fundamentals of safety system design. This document was prepared to help explain the content of the revision.
In considering safety protection in the measures to reduce machine risks, it has long been common practice to evaluate levels of risk reduction and the performance of a safety related control system in terms of Categories as specified in the international standard ISO13849-1: 199 (based on the European standard EN954-1).
A Category is a classification of the architecture (structure) of a safety related control system. The concept was originally based on established technologies using electromechanical components such as switched and relays and simple electrical components. The behavior of these control systems in the event of a component failure can be determined to a high level of certainty because the failure modes of these components can be completely defined.