Spring 2011, Vol 13, No. 2

Recent Earthquakes have shown that the electrical substations are very vulnerable,and direct and indirect losses resulting from their damages are highly considerable. post insulators in high-voltage substations are usually used as support for the bus bars or flexible conductors. Due to their height, low lateral stiffness and brittle materials used for the main core of such component, they have shown very poor seismic performance. In this paper, the seismic behavior of two 63kV and 132kV PIs with flexible connections to their top is studied experimentaly. Tests samples consist of individual post insulators mounted directly on the simulator platform followed by tests of complete post insulators mounted on the lattice steel structure as the support. Insulators were subjected to two different sets of inputs, first a set of sine sweeps and the second set was earthquake simulations time histories. The results of the experiments were used to verify the numerical models for further complementary assessments. The results show that they have very high frequencies and hardly can get damaged due to resonance, but the lattice steel structure decreased the natural frequencies by almost 70%, which amplifies the acceleration by %25.