In the early 1990s, a new type of high-voltage electrical appliance with high- voltage electrical insulation completely different from the traditional structure at home and abroad—oil-free, air-free, and porcelain-free fluoroplastics as internal insulation and silicone rubber as external insulation—appeared on the Chinese earth Wall casing . Different from traditional oil-filled porcelain bushings, it has a unique design idea and novel structure. Some of its technical characteristics have exceeded the international standard IEC and China's national standard GB, and are used by more and more users.
So far, this type of dry series products, including wall bushings, current transformers and cable terminations, have made great progress and rapid development. This product has the outstanding advantages of no oil, no gas, no porcelain, small size, light weight, fire resistance, explosion protection, and anti-pollution flashover. Since 1990, more than 10,000 of the above products have been operating safely in the power system, and have not occurred An accident.
As we all know, in the domestic or foreign market, oil-filled porcelain bushings are mostly used in traditional high-voltage wall bushings , cable terminal heads, current transformers, etc. of 66Kv and above. It has some potential problems such as leakage, flammability, explosion, pollution flash, heavy maintenance workload, large volume and heavy quality. As the environment worsens, pollution flashes on the porcelain surface often occur, and the probability of flashover increases with the degree of environmental pollution. In the past, it has been solved by increasing the leakage ratio, but the increase of the leakage ratio is limited. The larger the leakage ratio, the lower the firing rate of the porcelain casing. Therefore, we developed a A new generation of products with a new structural design and completely different materials from the past.
The development of dry high - voltage through-wall bushings , in the early 1990s, with the development of urban network reconstruction, urban indoor substations quickly developed, and the demand for through-wall bushings was increasing. In the face of the above problems, we must take a unique new road to replace the oil porcelain insulation with organic insulation materials.
In 1990, we developed the first batch of 9 STA-type wall bushings and operated them at Dalian Laohutan Substation, and then operated more than 200 in Northeast and Yunnan. However, there are some disadvantages to STA wall bushings . Because it is made of cross-linked polyethylene cable, both ends need to be supported by pillar insulators . To this end, we successfully developed the STB high-voltage wall bushing in 1994. So far, more than 10,000 STB bushings have been running on the power grid, covering more than 20 provinces and cities from Hainan to Daqing, from the East Coast to Xinjiang.