To predict the effect of outages in power system the technique called contingency analysis is done. Contingency like failures of equipment, transmission line etc. The off line analysis to predict the effect of individual contingency of a power system is done, and power system contains large number of components. Practically only selected contingencies will lead to severe conditions in power system like violation of voltage and active power limits. The process of identifying these severe contingencies is referred as contingency selection and this can be done by calculating performance indices for each contingencies.