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Compared with conventional porcelain bushings, polymeric ones are light and therefore possess improved seismic performance. They are also explosion proof with no scattering when broken and are highly stain resistant. In particular, the polymeric bushings coated with silicone rubber show good voltage resistance performance, even when covered with salt deposits. That is, by covering the surface with silicone rubber, the hydrophobic nature of the polymer bushing becomes excellent. This reduces the risk of the occurrence of surface arc discharges and flashovers. Therefore, as shown in Figure 1, the length of a typical polymer bushing insulated with pressurized SF6 can be reduced significantly compared with a conventional porcelain bushing insulated with oil-impregnated paper (OIP) of the same voltage class. The weight can be reduced drastically as well. [ABSTRACT FROM AUTHOR]

In the actual operation, converter transformer valve side bushings are subjected to high voltages and large current loads with large number of harmonics simultaneously. In our previous papers, using the 3‐D electromagnetic‐fluid‐thermal coupling analysis method, the 3‐D temperature distribution of a converter transformer valve side bushing was researched, and the heating and dissipation characteristics of the bushing were analyzed. However, the electric field distribution of the bushing is affected by the temperature gradient inside the bushing. Related researches about the electro‐thermal coupling field of the bushing are rare and most researches are concentrated on the single factor of voltage or temperature. In this paper, by using the electro‐thermal coupling field simulation method proposed in our previous paper, the effect of the core outline size on the electric field distribution of the bushing under a certain temperature gradient was investigated. In addition, by using the transient electric field simulation method, the electric field distribution of the bushing in one cycle subjected to an actual voltage waveform and the current in temperature rise test simultaneously was analyzed considering the effect of the Joule heating power of the core. The proposed method will be able to provide a computation basis for the structure design and optimization of converter transformer valve side bushings. © 2020 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

SUMMARY In Tohoku Region Pacific Coast Earthquake, many of the power equipment (especially center clamping type bushings for power transformers) were damaged due to the seismic motion that exceeds the design criteria. The problem of the conventional seismic analysis became clear as the actual damage was revealed. Since elaboration of seismic analysis and evaluation technology was called for, the elaboration possibility of seismic analysis was verified by carrying out comparison with various test results and the analysis result by the latest technique. [ABSTRACT FROM AUTHOR]