Reliability of 3-state device systems with simultaneous failures

This work is concerned with computing the reliability of redundant systems of three-state (e.g., good, failed-open or failed-short) devices. Allowing for multiple failures, formulas are presented for calculating the reliability of a parallel-series system or a series-parallel system which is formed from three-state, non-DFM (dual failure-mode) devices, and which might require multiple paths to function. The words series and parallel are used in the layout-diagram sense. The formulation encompasses cases which have been analyzed by complex methods in numerous papers on the reliability of three-state DFM device systems. The effects of dominant failure-modes on the relationship between reliability of a series system and that of a parallel system, and on the relationship between the reliability of a parallel-series system and that of series-parallel system are presented.<
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