Seismic response of electrical substation equipment interconnected by flexible conductors

In this paper we investigate experimentally the dynamic interaction between components of electrical substation equipment interconnected by flexible (cable) conductors. Shake table tests were conducted on five different pairs of generic substation equipment specimens interconnected by three different flexible conductors with three different levels of slackness. No damage to any of the three flexible conductors was observed during any of the seismic tests conducted. Two different types of dynamic response were observed during the seismic tests. The first type involves low interaction between the interconnected equipment due to a large slack and/or low intensity ground motion. For this case, very different frequency contents among the relative displacement, absolute acceleration, and force response of each piece of equipment were observed. Also, large horizontal movement of the more flexible equipment was transferred almost entirely into vertical motion of the conductor with little transmission to the more rigid equipment. The second type of dynamic response involves high interaction between interconnected equipment due to a small slack and/or high intensity ground motion. For this case, large vertical acceleration pulses were observed at midspan of the conductor.