The World’s First ±400kV/5000A Dry-type AC/DC Vacuum Impregnated Fiber Wall Bushing Passed Type Test

The ±400kV/5000A dry-type AC/DC vacuum impregnated fiber wall bushing, a self-developed product by Nanjing Bushing Factory, has passed type test conducted by Quality Inspection and Test Center for power equipment and apparatus of China Electric Power Research Institute. Main insulator of the bushing serves as vacuum impregnated fiber capacitor core, vacuum impregnated fiber capacitor core applies high performance insulating fiber wrapped into an insulating layer, capacitive screen applies semiconducting material, on reaching design requirement for alternate wrap interval setting between insulating layer and capacitive screen, impregnate epoxy resin compound in vacuum, then produce vacuum impregnated fiber capacitor core through the process of high temperature solidification.

Vacuum impregnated fiber capacitor core, attachment flange, external insulating creepage umbrella dress and other accessories are assembled into vacuum impregnated fiber capacitive dry-type bushing. Manufacturing technique of bushing as such combines merits of high insulating strength of impregnated paper capacitive bushing and outstanding mechanical properties of glass fiber reinforced dry-type bushing, making the product more stable during operation.

After finishing the manufacturing process, the factory lab conducted 120% horizontal margin test on insulation, after passing the test, the equipment was transported to the experimental base of China Southern Power Grid in Kun Ming to proceed high altitude DC withstand test and passed.

Quality Inspection and Test Center for Power Equipment and Apparatus of China Electric Power Research Institute conducted type test on the product in July 2015, Not only does the bushing meets the GB/T 22674-2008 <Bushing for DC System> and GB/T 4109-2008 <Insulating Bushing Applying AC Voltage Higher than 1000V> standards, partial discharge of the bushing also maintains lower than 5 during 2-hour 680kV DC withstand, number PD impulse ≥2000pC is 0 in the last 30 minutes.