Study on Seismic Performance of a Mold Transformer through Shaking Table Tests

Ngoc Hieu Dinh,Seung-Jae Lee,Kyoung-Kyu Choi,Joo-Young Kim

doi:10.3390/app10010361

Abstract

This study presents an experimental seismic investigation of a 1000 kVA cast resin-type hybrid mold transformer through tri-axial shaking table tests. The input acceleration time histories were generated in accordance with the specifications recommended by the International Code Council Evaluation Services Acceptance Criteria ICC-ES AC156 code, with scaling factors in the range of 25–300%. The damage and the dynamic characteristics of the mold transformer were evaluated in terms of the fundamental frequency, damping ratio, acceleration time history responses, dynamic amplification factors, and relative displacement. The shaking table test results showed that the damage of the mold transformer was mainly governed by the severe slippage of the spacers and the loosening of the linked bolts between the bottom beam and the bed beam. In addition, the maximum relative displacement at the top beam in Y and Z-directions exceeded the boundary limit recommended by the Korean National Radio Research Agency. Moreover, the operational test of the specimen was performed based on the IEC 60076-11 Standard before and after the shaking table test series to ensure the operational capacity of the transformer.

Highlights

Non-structural elements that are attached to or supported by structural components play various functions and services in maintaining operation in existing buildings, and to support human activities.According to the complete classification specified in Federal Emergency Management Agency (FEMA)FEMA-74 [1], non-structural elements can be classified into three main categories of architectural components, mechanical and electrical components, and building furnishings and contents
Depending on the dynamic characteristics, electrical components can be exposed to high-frequency acceleration arising from resonance effects, which result in the loosening of anchor bolts or connecting fasteners, and damage to enclosed plates and frames [4]
The transfer function amplitude was determined as the ratio between the Fourier transformation of the input signals, and the response output signals collected from accelerometer data installed on the several points of the mold transformer [7,8,11,18]

Summary

Introduction

FEMA-74 [1], non-structural elements can be classified into three main categories of architectural components, mechanical and electrical components, and building furnishings and contents. The non-structural elements account for a high percentage of 82–92% of the total economic investment, while structural components account for the remaining 18–8% [2]. It is obvious that in several vital types of buildings, such as hospitals, high-tech laboratories, power stations, etc., the loss of non-structural elements due to natural disasters could lead to huge replacement costs [3]. During the past few decades, strong earthquake ground motions have caused severe physical, as well as functional, damage to non-structural elements, especially to electrical components, which have led to major operational failures and economic loss of electrical power systems in buildings and special facilities.

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Conclusion