An Experimental Study on the Dynamic Interaction of Interconnected Electrical Equipment during Earthquakes

High voltage substation equipment has been vulnerable to earthquake events. Substation equipment performance during earthquakes can also be affected by the dynamic interaction between equipments components. This paper first briefly summarizes the performance of substation equipment during recent earthquakes in the United States. Thereafter, the results of an experimental investigation of the dynamic interaction between components of electrical substation equipment interconnected by rigid bus conductors are presented. Shake table tests were conducted on five different pairs of generic substation equipment specimens interconnected by three different rigid bus assemblies. All connectors tested exhibit stable hysteretic behavior with various degrees of energy dissipation capacity. The first connectors incorporates a spring dissipates energy through yielding and generated the highest forces among the connectors tested, and generally caused an amplification of the dynamic response of one of the interconnected equipment components. The second connector includes a bus slider that dissipates energy through friction and generated lower forces than the spring connector did. Its high damping capacity, however, systematically reduced the dynamic response of interconnected equipment components. Finally, a special seismic connector that incorporates three flexural vertical aluminum cables generated the lowest forces. Its minimal damping capacity, however, resulted in higher equipment dynamic response than with the bus slider.