The normal operation of the electric equipment in the railway signal equipment has played an important role in the safety operation and operation efficiency. A variety of fuse sizes have been used in the electric equipment. They can be devided into three grades. The paper has mainly introduced the fuses equipment and their function of the electric equipment 6502. Analysis and discussion on selecting the protective fuses for each grade in the three have been performed. The theoretical analysis and field surveying have concluded that the capacity of the fuses of the first grade should be selected by the capacity of the power screen, the mid-value method should be adopted in capacity selecting of the fuses in the 2nd grade and the 3rd grade fuses should be ensured by the maximum loads current.%铁路信号设备中电气集中设备的正常运行对行车安全和行车效率起着举足轻重的作用．电气集中设备中设有各种规格的熔断器，可归为三级防护．详细介绍了6502电气集中设备熔断器的设备和作用，并对三级防护的各级防护熔断器的选择进行了逐级分析和探讨，理论分析和现场实测认为：第一级熔断器的容量按电源屏容量要求选择；第二级熔断器的容量选择采用中值法；第三级熔断器则根据最大负载电流来确定．
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