On October 26, the 550kV UHV glue impregnated paper dry bushing independently developed by Nanjing Electric passed the type test of bushing products of China Electric Power Research Institute. The casing is a substitute for the imported products of HSP company, and its technical level is leading in the world.

In December 2019, Nanjing electric and Guiyang Bureau of EHV transmission company of China Southern Power Grid Co., Ltd. signed the research contract of 550kV glue impregnated paper dry bushing project to replace the imported HSP EHV product. The project is the company's key R & D project in 2020. Compared with the conventional 550kV dry bushing, the outer diameter and length of the new 550kV glue impregnated paper dry bushing are smaller. The compact size of insulation in oil increases the difficulty of product design and production.

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

The test results show that the electrical, mechanical and thermal properties of the product are good, and the insulation tolerance, partial discharge, temperature rise and other key indicators meet the requirements of technical specifications and relevant standards. The successful development of this bushing is a challenge for Nanjing Electric in terms of research and development, as well as an improvement of production capacity, which indicates that Nanjing Electric has the design capacity, production capacity and test capacity of international leading ultra-high voltage products.