Research and design of an innovative medium voltage removable metal-enclosed switchgear

The paper presents an innovative design scheme of the removable metal-enclosed switchgear, in which the three-phase main circuits are longitudinal layout if looking from the front of the cabinet, and the main circuit is mainly composed of tubular conductors, with a linear moving disconnector on each side of the vacuum interrupter. The reasons for this design and the ways to achieve it are discussed. The complex model's dielectric properties are described with emphasis on electrical field calculations, the results show that its electric field is obviously superior to the switchgears which usually adopt rectangular conductors on the market. And the heat and temperature rise of the main conduction circuit considering the skin effect is studied, which proves that the use of tubular conductor can greatly reduce the heat generation. A typical 12kV / 1250A product prototype of this design is manufactured and tested, by which it is verified this scheme at least has the flowing typical advantages. The main conductive circuit is greatly shortened and a lot of material is saved accordingly. Its width is only 500mm and the partial discharge of the whole machine is less than 5pC, which are both minimum in the world with the same class.