| Damage of power transformers of substations in recent destructive earthquakes highlighted the urgent need for seismic retrofit of transformers. Base isolation is considered one of the possible retrofit measures. This research represents the first comprehensive experimental and analytical study of base isolation technology for seismic protection of transformer/bushing systems. Applicability of base isolation for seismic protection of a transformer system (usually with bushings on the top) was experimentally and analytically studied. Tri-axial earthquake simulator testing with a large-size model of a transformer was conducted. Two types of isolation systems, a sliding bearing system and a segmented high-damping rubber bearing system, were developed and applied to the testing. A simplified numerical model was proposed and the simulation results were compared with the test results. Some difficulty in the design of the isolation system was pointed out, and a solution was presented. Through the research, base isolation was proven as a highly prospective measure for seismic protection of power transformers. |
