Automation engineering systems are increasingly handling safety-relevant tasks. For example, processes representing a hazard to people and the environment are monitored by safety systems. These take appropriate action in the event of a fault, and can reduce the risk of a hazardous state. Functional safety is the correct functioning of such equipment.
Up to now, national standards have existed for the planning, construction and operation of safety-related systems (SRS) . On the German market, for example, the manufacturers and owners of such plants could refer to the safety standards DIN/VDE 19250, DIN/VDE 19251 and DIN/VDE 801.
Since many countries had different standards for the correct functioning of safety-relevant equipment, a globally applicable IEC basic standard for functional safety was adopted in 1998. A series of standards was derived from this, in which the organizational and technical demands placed on safety-related systems and their implementation were defined.
A uniform standard for plants in the process industry was adopted in 2003. The following two standards are of significance to process instrumentation:
• EC 61508 (basic standard): Globally applicable as the basis for specifications, design and operation of safety-related systems (SRS).
• EC 61511 (application-specific standard for the process industry): Implementation of IEC 61508 for the process industry