Seismic response of high-voltage transformer-bushing systems incorporating flexural stiffeners II: Experimental study

Anumerical study conducted on four transformer-bushing models presented in a first companion paper indicated that high-voltage bushings mounted on the cover plates of transformers are more vulnerable to seismic loading than bushings mounted on a rigid base. This would explain why the good performance of bushings mounted on a rigid base observed during shake table testing does not correlate well with their performance in the field. In this second companion paper, the addition of flexural stiffeners on the transformer cover plates as a means to stiffen the base of bushings and mitigate their seismic vulnerability is investigated experimentally. Shake table testing was conducted on a 230kV porcelain bushing mounted on a support structure incorporating a flexible cover plate and two stiffener configurations. Test results confirmed that stiffening the cover plates is beneficial to the seismic response of high-voltage bushings. Test results are compared to the predictions of finite element analyses.