DAMPING CAPABILITY ENHANCEMENT OF THE POLYURETHANE SEISMIC ISOLATION DEVICE FOR HV POST INSULATORS

In the past earthquakes, components of high-voltage substation systems suffered damages and it led to interrupt power transmission. Because of the damages, electrical utilities hurt financial losses and the lag in restoring power caused delays in the essential services. The porcelain post insulators are primary and vulnerable components in most power substations. Its failure may dreadfully affect local network or the entire grid. Seismic isolation is an effective method to increase seismic safety of the electrical system. A novel low-cost polyurethane seismic isolation device has been developed to protect HV post insulators. In the seismically isolated insulators, relatively large displacements may occur for some earthquakes and it may cause electric clearance problems in the system. The supplementary thin steel yielding plates are developed to enhance damping capability of the seismic isolation device. The seismic isolation device with assorted damping capabilities are positioned between the fixed support and 420-kV post insulator. The efficiency of the yielding plates is evaluated by means of two discrete methods. Nonlinear time history analyses are carried out for three acceleration records that are scaled according to IEEE-693. The comparisons of acceleration and displacement responses of the bare base isolated and the base isolated with supplementary dampers demonstrate that the new damping mechanism works efficiently.