Influence of Dynamic Interaction Between Interconnected Electrical Substation Equipment on Seismic Response

Effects of dynamic interaction between substation equipment in multi-connected systems on seismic response has been investigated. Also, influence of record to record and intensity variability on interaction results is studied. Three dimensional models of four vulnerable types of equipment including surge arrester, current transformer, circuit breaker and disconnect switch are developed and verified. Six different systems of equipment connected through rigid bus bars comprising of two, three and four equipment are considered. Incremental dynamic analysis is carried out on models using three-component records. Ratio of maximum responses in connected condition to those in unconnected condition has been utilized as interaction measure. Considering more than two-connected equipment and using three dimensional models are novelties of this paper. Importance of considering more than two-connected equipment has been demonstrated. It is found that for equipment in which contribution of higher modes on responses are notable, variation of ground motion features such as frequency content have more effect on interaction results than equipment in which natural frequency is dominant on responses. It is concluded that variability of record has more significant influence on interaction results than variation of seismic intensity. Differences in response ratios were higher at low intensities as compared to high intensity levels. High stiffness of connector at low intensities is the main reason for this result.