The Reliability of Periodically Repaired n − I/n Parallel Redundant Systems

The average failure rate of an n − 1/n parallel redundant system of n identical elements, each of which has a constant failure rate of λ, that is repaired every T hours can be approximated by the upper bound n(n − 1)λ²T/2. If λT < 1, the ratio of the upper bound to the actual average failure rate is less than or equal to I + (n −)λT/I − λT/2. These formulas provide a convenient method for predicting the reliability of such systems with a quantitative error bound.