American Box Type Substation

Overview

Since the 1990s, my country has introduced the American box-type substation, and the structure of the load switch, the ring network switch and the fuse has been simplified into the transformer oil tank and immersed in the oil. The arrester also adopts oil-immersed zinc oxide arrester. The transformer cancels the oil pillow, and the fuel tank and radiator are exposed to the air. This kind of box change is called American box change, which is likened to a box hanging next to the transformer. In terms of volume, European-style box-type transformers are relatively large due to the internal installation of conventional switch cabinets and transformers. The American box-type transformer has a smaller volume due to the integrated installation. In terms of protection, the high-voltage side of the European box transformer is protected by a load switch and a current-limiting fuse. When the one-phase fuse is blown, use the striker of the fuse to open the three-phase load switch at the same time to avoid phase loss operation, and the load switch is required to have the ability to cut off and transfer current. The low-voltage side is protected by a load switch and a current-limiting fuse, and the high-voltage side of the American box transformer is protected by a fuse, while the load switch only has the function of switching and cutting off the high-voltage load current, and the capacity is small. When a phase fuse on the high-voltage side is blown, the voltage on the low-voltage side will decrease, and the under-voltage protection or over-current protection of the plastic case automatic air switch will act, and low-voltage operation will not occur. From the perspective of product cost, the cost of European-style boxes is high. From the perspective of product price reduction space, there is still a large price reduction space for American box transformers. On the one hand, the three-phase five-column iron core of the American box transformer can be changed to a three-phase three-column iron core. On the other hand, the high-voltage part of the American box transformer can be modified from The transformer oil tank is moved to the outside of the oil tank, occupying the space of the high-voltage room.