Seismic Behavior of ۶۳kV and ۱۳۲kV Substation Post Insulators with Flexible Conductors, an Experimental Approach

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 ۶۳kV and ۱۳۲kV PIs with flexible connections to their top is studied experimentally. 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 ۷۰%, which amplifies the acceleration by %۲۵.