Observability, reliability and sensor positioning
Résumé
The analysis of data measured on operating plan depends strongly on the measurement design. In this field, one of the most important problem is, probably the selection of the measurement placements which plays an important role in the design of instrumentation either in a new plant or in the study of an operating plant. For a given process, our aim is to assess the availability of the necessary information for the process control and to define the sensor location in order that the necessary variables for control remains always observable even if one or more sensors become defective. In this communication, the authors present an original method for analyzing the reliability of an instrumental system architecture. Underlying, it is pointed out the necessary connections between several concepts: observability, redundancy, sensate positioning, reliability. The presentation is based on several reduced dimension examples that will be easily replaced by a more general plant: in the paper, indications are given and general rules are proposed to solve the case of large dimension problems. The optimal sensor placement is also explored as a consequence of the reliability and the observability constraints.