As one of the two new wings of Beijing, Beijing Sub Center strives to build itself into a world-class demonstration area of harmonious and livable city, a new urbanization demonstration area, and a collaborative development demonstration area of Beijing Tianjin Hebei region. The construction of Beijing Urban sub center is proposed for the needs of adjusting the spatial pattern of Beijing, controlling urban diseases, expanding new space for development, promoting the coordinated development of Beijing, Tianjin and Hebei, and exploring the optimal development mode of densely populated and economic areas. SG (b) series non encapsulated dry-type transformer product description: the low-voltage winding is made of high-quality copper foil and high-temperature insulating material, which is solidified into a solid whole by VPI vacuum pressure impregnation, with strong impact resistance; The high-voltage winding is made of pressed cake or continuous structure, and the interlayer insulation is made of C-grade insulating Nomex Paper, which is impregnated by VPI vacuum pressure and solidified at high temperature, with strong short-circuit resistance; The iron core is made of high-quality and high magnetic conductivity silicon steel with multi-stage stepping process and low no-load loss; After the service life, copper and silicon steel can be recycled, and the insulation material is completely degraded, which is an environment-friendly product; It is the first one in China to pass the fire resistance, environment and climate test of European standard HD464; DuPont relatran ® Core technology, volume reduction of 10%, material saving of 10%, insulation grade up to C level（ Reliable; reliable; Transformers, reliatran ® It means: reliable transformer) can realize full intelligent data acquisition and analysis, intelligent "brain", active operation and maintenance; Scope of application: for shopping malls, residential areas, schools, hospitals and other places with high population density and strict safety requirements.