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Due to failures of interconnected equipment in recent earthquakes, it is suspected that the seismic interaction of the flexible conductors with the equipment during a strong ground motion could cause additional unpredicted forces, resulting in damage or collapse of the equipment they interconnect. This paper presents the results of an investigation into the dynamic behavior of flexible conductors by performing several shake table tests on a class of flexible conductors and the relevant 500-kV interconnected equipment used in substations throughout the province of British Columbia in Canada. The test specimen consisted of large scale models of the equipment items and the actual size flexible conductors. The shake table input records were synthetic earthquakes generated to fit an IEEE prescribed response spectrum. This investigation showed that the dynamic effect of flexible conductors must be considered when evaluating the seismic capacity of interconnected equipment. Index Terms--Conductor mounting forces, dynamic behavior, flexible stranded conductors, seismic loading, seismic response, shake table, substation equipment.

Prompted by recent failures in earthquakes of interconnected high-voltage electrical equipment in substations and a lack of available design information, BC Hydro initiated an experimental program to address this issue. Powertech Labs, in collaboration with BC Hydro and the University of British Columbia (UBC), formulated a research plan to investigate how flexible conductors affect the seismic response of interconnected substation equipment. This paper describes the result of static tests on flexible conductors and of calculations of dynamic properties of equipment in BC Hydro substations. For a set of six interconnected configurations the natural frequencies were calculated and where possible, calibrated to the measured natural frequencies of the equipment. Index Terms--Dynamic finite-element analysis, field measurement of dynamic properties, flexible stranded conductors, seismic performance, substation equipment.