A novel measure of component importance considering cost for all-digital protection systems

Component importance analysis plays an important role in system reliability theory. This paper proposes a novel measure of component importance for all-digital protection systems, which considers both the manufacturing cost and the failure cost. First, the function of manufacturing cost versus component failure rate is proposed, and the function of total cost versus system reliability for all-digital protection systems is derived. Second, the measure of importance considering cost with respect to component as well as component type is defined, and related calculation equations are derived. Afterwards, the component importance for a typical all-digital protection system is analyzed and discussed, which demonstrates the application value of the new measure of component importance. A conclusion about the benefits of the application principle and method of the new measure is given at the end.