RELIABILITY System Reliability Components in series Components in

RELIABILITY • System Reliability – Components in series – Components in parallel – Combination system 1

Reliability • Reliability provides a numerical measure of “degree of excellence” through time. – Failure: the inability of an equipment to perform its required function – Reliability: the probability of no failure throughout a prescribed operating period. 2

System Reliability • Most products are made up of a number of components • The reliability of each component and the configuration of the system consisting of these components determines the system reliability (i. e. , the reliability of the product). • The components may be in – series: system operates if all components operate – parallel: system operates if any component operates – combination of series and parallel 3

Components in Series • If the components are in series, the system operates if all the components operate • If there are n components in series, where the reliability if the i-th component is denoted by ri , the system reliability is 4

Components in Series Example 6: A module of a satellite monitoring system has 500 components in series. The reliability of each component is 0. 999. Find the reliability of the module. If the number of components is reduced to 200, what is the reliability? 5

Components in Parallel • If the components are in parallel, the system operates if any component operates • If there are n components in parallel, where the reliability of the i-th component is denoted by ri , the system reliability is 6

Components in Parallel Example 7: Find the reliability of a system with three components, A, B, and C in parallel. The reliabilities of A, B, and C are 0. 95, 0. 92, and 0. 90, respectively. 7

Redundant Systems and Backup Components • If a system contains a backup or spare components, it can be treated as the one with components in parallel. The following formula is equivalent to 8

Combination System Example 8: Find the reliability of of the following system 9