Abstract : Based on the construction and installation of the fire protection system at Yuci North Freight Yard, this paper introduces a constant pressure fire water supply system composed of electrical control cabinets, frequency converters, PID controllers, pressure sensors, and water pump motors. It points out that this system has advantages such as fast response speed, strong adaptability, and wide protection coverage in the event of a fire. Keywords : Freight yard, frequency converter technology, fire water supply system [b]Introduction[/b] In the fire water supply system of railway freight yards, low-pressure pipelines are mostly used. The water pressure in the pipeline network is usually low, and the pressure required for fire hoses at the fire scene is pressurized by fire trucks or other mobile fire pumps. This is mainly because the traditional water tower regulation method is used, but water towers are limited by technical and economic factors and cannot be built to a sufficient height to meet the fire water supply pressure. The pressure at the fire station can be calculated using the formula for calculating the pressure of a high-pressure pipeline fire hydrant: H_hydrant = H_standard + h_belt + h_gun = 10 + 14.22 + 17 = 41.22. In the formula: H_hydrant—the pressure that the fire hydrant at the most unfavorable point in the pipeline network should maintain; H_standard—the elevation difference between the fire hydrant and the firefighter standing at the most unfavorable point, generally the height of the tallest building in the freight yard will not be less than 10m; h_h hose—the sum of the head losses of 6 65nm diameter hemp hoses, with a solid water column of 12mm for a 19nm diameter fire hose and a flow rate of 5.2L/s, the head loss is 6x2.37=14.22; h_gun—the pressure required for a fire hose with a solid water column of not less than 10m and a flow rate of not less than 5L/s, at which point the pressure at the nozzle is 17. If the head loss of the pipeline is added, the pressure required for the entire fire protection pipeline network is much greater than 41.22. In railway freight yards, the probability of a fire is relatively small, and the water is mainly used for domestic and industrial purposes, requiring relatively low water pressure. If a water tower is built solely from a fire protection perspective, the pump head will inevitably be greatly increased, resulting in a large amount of electricity consumption. Meanwhile, because Shanxi is located in a collapsible loess region, high water towers will cause underground pipelines to be under high pressure for extended periods, increasing the likelihood of pipeline leaks and causing localized subsidence of the pipeline foundation, ultimately leading to pipeline rupture. Since low-pressure pipeline fire water supply relies heavily on fire trucks and booster pumps, its response to fires is relatively slow. Therefore, to address this issue, digital frequency conversion technology was applied to the fire water supply system in the Yubei Freight Yard fire protection project, achieving good results. [b][align=center]For details, please click: Application of Frequency Converter Speed ​​Regulation Constant Pressure System in Freight Yard Fire Protection[/align][/b]