Alternating Test Strategy for Multi-State Safety System Performance Analysis

This paper presents an alternating test strategy for multi-state Safety Instrumented Systems (SIS) by considering the proof testing parameters according to the observed state in the current test. An approach based on the model of Dynamic Bayesian Network (DBN) is developed to assess the SIS unavailability. The developed model is used for determining the average system performance according to proof tests parameters for a certain service period. Then, the strategy is applied on SIS actuator layer where a structural redundancy is considered. A case study is presented to illustrate the benefits of the proposed testing strategy in improving the SIS performance.