Development of 1 100 kV UHV A.C.Transformer Bushing

During UHV bushing development,uniform capacitance grading was maintained by even step thickness and layer insulation margin,but capacitance grading for main insulation design.The condenser core was made of coiled paper 9 842 mm in length and 190 layers of electrodes.The lower insulator was of 1700 mm in height.The axial shielding at lower insulator was adopted taking full advantage of its effective longitudinal insulation length.Integrated sealing components consists of powerful springs,bolt-nut tighting,elastic plate,local axial positioning.and resilient rubber gasket.For thick condenser core with coiled paper,an integrated conducting tube consisting of a hard brass pipe and a copper tube is used.The porcelain shells are made of high strength porcelain material.Enforced ribs are provided on the frange between top collar and flange plate.The bushing has savety margin of more than 5 in respect of bending strength and 1.96 in respect of seismic strength.Finland made quality cable paper was used,and magnet-isolated brass or aluminium material was used for oil expansion head,flanges,base and conducting tube.The developed bushing has reliable technical performance as compared with foreign ones,suitable for use at UHV transmission line in China.