Numéro : 2238 - Year : 1994
Control-command system RAMS
D. PEREZ, Chef du Groupe Etudes de Sûreté, MERLIN GERIN
The fail-safe operation of a process is above ail a practical value. The control monitoring "supports" this practical value and is emerging as an essential factor in process safely. Therefore, the need for "fail-safe operation" has led to the development of specific techniques suited to the design of fail-safe automatic control systems.
Of these specific techniques, two fields have undergone recent developments: software dependability and system modelling techniques.
The use of these techniques essentially depends on the type of instrumentation and control. The presence of the operator, the types of sensor/actuator and the operating conditions are all factors which should be taken into account systematically. in practice, for each type of instrumentation and control (protection system, control system, supervision system, etc.), there is a technical solution suited to the specific safely requirements. After giving a brief summary of the slate of the art for the different automatic control system classes, the paper concentrates on techniques used for protection systems.