Weaknesses of the conventional three-state model in station-oriented reliability evaluation

The independent component-based three-state model has been widely used in station-oriented reliability assessment. The possible weaknesses of this conventional model are analyzed in the paper. The results show that practical restorative actions and existing dependencies cannot be completely represented using this model. Errors due to using the three-state model are affected by the component failure, repair and switching parameters, and may be significant for some system states or particular applications. In addition, practical factors, e.g. stuck breaker conditions and normally open components cannot be represented directly by the three-state model. An extended model is therefore required as an alternative for some particular applications in which the error associated with the three-state model are significant or the pertinent factors require detailed recognition.