Author(s)

A. D. Shendge

Abstract

The safety of the transformer and the environment around the plant should be ensured against all natural hazards including earthquakes. With public safety as the paramount concern, the transformer is designed to withstand low probability high magnitude earthquakes. This paper deals with seismic design aspects of a 50MVA, 110KV power transformer such as the ground motion generation, seismic analysis and earthquake qualification, etc. The finite element analysis tool has been used to carry out modal analysis and spectrum (mode combination) analysis. Spectral analysis is used to combine the effect of the structure’s modes on one of the equipment modes and, also, combine the effect of equipment modes with respect to stresses or displacements in the equipment modes of the structure Keywords: earthquake, transformer, seismic design, dynamic analysis, response spectrum, and finite element analysis. 1 Introduction A transformer consists of various structures, which are designed to resist earthquake forces. Earthquake is a natural phenomenon, which is generated in earth crust in the form of seismic waves, generating ground vibrations travelling far and wide and gets attenuated as they travel. Such ground vibrations or base motion at the base of the transformer [Fig.1] gets transmitted through the under base of the transformer to the structure such as core, coil, conservator, radiator, bushing and tank mounted lightning arrestor. The earthquake motion mainly induces inertial forces in the structure. The Transformer structure is designed to resist these earthquake forces along with other loads, viz. Gravity, pressure, wind load pull and thermal loads etc. The detailed seismic requirement [1] for each component, including whether it is required to operate after an earthquake, or

Keywords

earthquake, transformer, seismic design, dynamic analysis, response spectrum, and finite element analysis.