A Method for Redundancy Scheme Performance Assessment

A method is described for quantitatively expressing the performance of a redundancy scheme by two parameters, the reliability improvement index and the "cost" factor, which are defined so as to be independent of the size of system to which they are applied. The reliability improvement index is a sensitive measure of the reliability increase produced by applying the redundancy scheme, and is relatively easy to evaluate by considering failure modes in a small representative part of the system. The two parameters permit a comparative assessment of redundancy schemes, and some results for a selection of redundancy schemes are presented. The reliability improvement index can also be used to estimate redundant system reliability.