Evaluation of seismic performance of an electric substation using event tree/fault tree technique

In this study, we use the event tree/fault tree technique to evaluate the performance of an electric substation in the event of an earthquake. The substation is considered as a combination of components (equipment and structures), and the event trees and fault trees are established to delineate the interrelationships of these components. Using the fragility data of individual components in the event trees and fault trees, the probabilities that the substation as a whole fails at various levels of ground shaking can be determined and displayed as substation fragility curves. Furthermore, using the minimum cut set technique, the most critical and vulnerable component in the substation can be identified. Substation 21, a key electric power supplier to several major hospitals in downtown Memphis, is selected to illustrate this technique.