On October 26, the 550kV pressure-adhesive paper-impregnated dry-type bushing independently developed by Nanjing Electric passed the type test of the bushing product of the China Electric Power Research Institute. The casing is a substitute for imported HSP products.

In December 2019, Nanjing Electric and China Southern Power Grid Co., Ltd. Pressure Transmission Company Guiyang Bureau signed a research contract to replace imported HSP pressure products-550kV glue-impregnated paper dry casing project. This project is the company's key research and development project in 2020. Compared with the conventional 550kV dry bushing, the new product of 550kV glue-impregnated paper dry bushing has a smaller outer diameter and shorter length of insulation in oil. The compact size of the insulation in oil increases the difficulty of product design and production.

With the unremitting efforts of the design, production, operation, procurement, and quality inspection departments, it took 9 months to complete the R&D, design and manufacturing of the bushing. The China Electric Power Research Institute Co., Ltd. was entrusted from October 20 to 26, 2020. The Wuhan branch of the company conducted a type test of the bushing in our company, and at the same time invited relevant experts from China Southern Power Grid to test and witness. With the cooperation of various departments of the company, the type test of the casing was successfully completed.

The test results show that the product has good electrical, mechanical and thermal properties, and key indicators such as insulation tolerance, partial discharge, and temperature rise meet the technical specifications and relevant standards. The successful development of this bushing is a R&D challenge for Nanjing Electric, as well as an increase in production capacity. It indicates that Nanjing Electric has internationally leading design capabilities, production capabilities and test capabilities for pressure products.