SVU2-BF/....is the most powerful protection device used in the main distribution network. The product applies special spark-gap of arc suppression method and is fit with precise discharge gas and special arc extinguish plate. It can break the arc into several arc segments after discharge and extinguish them even if high power frequency after current occurs. Then subsequent current can be restricted after the electrical wire discharges, further improving the running safety and continuity of the protected equipment. This kind of lightning surge protection device has a standard module width of 36 mm. It is mostly used in B level lightning protection area in main distribution system, especially serves as high energy lightning current discharge distance. It can be used with SVU2-BfSVU3-BM between 3+1 circuit protection of TT and N and PE, realizing the thunder stroke protection in I level thunder stroke area. The key characteristic of this kind of lightning arrestor is that it can eliminate power grid power frequency after-current as high as 50KA in the 230/400V low voltage distribution system. Its continuous operating voltage as high as 440V guarantees that it can be used in the power system whose operating voltage is higher than 230V/400V. However, special attention should be paid to its special installation requirements. When this product is installed outdoor, it should be placed in a cabinet that is fireproof, waterproof, anticorrosion, and also can endure the pressure produced when discharging.