Abstract Research purposes:The DC frame leakage fault is the fault that can cause the big influence on the power supply system．Once this fault occurs，it will cause the large － scale power cut，and affect the normal running of the train．So reducing the scale influenced by the frame leakage fault and finding out the fault position rapidly and exactly are very crucial to shortening the power cut time and recovering the power supply as soon as possible．This paper researches and analyzes the three main schemes for frame leakage protection for getting the best cost performance scheme．
Research conclusions:The scheme of installing two sets of frame leakage protection devices is recommended． Namely，one set is for rectifiers and negative pole cabinet and the other one is for DC switch gears． With this scheme，the scale influenced by the fault can be reduced，the power cut time can be shortened，the reliability of the DC power supply system can be enhanced and the best cost performance can be obtained． So this scheme can be widely used in the projects．In addition，it is proposed it will be better to use this scheme along with the scheme of adopting the breaker in the DC incoming switch gear．
GB /T 25890． 7—2010，Railway Applications － Fixed Installations － DC Switchgear － Part 7 － 1: Measurement， Control and Protection Devices for Specific Use in d． c． Traction Systems － Application guide ［S］．
Wang Shuhe． Project Approachment of Integral Automation Monitoring System for Substation ［J］．Journal of Railway Engineering Society，2003( 4) : 111 －123．
Zhao Wulong，Liu Aihua． Discussing of the Transfer Trip Scheme of Frame Fault Protection of the Established Substation ［J］． Electric Railway，2009( 1) :48 － 50．
［11］王晓保． 钢轨电位限制装置与框架保护关系的分析［J］．城市轨道交通研究，2004( 6) :56 －58． Wang Xiaobao． Relation between Rail Over － voltage Protection Device and Frame Protection ［J］． Urban Mass Transit，2004(6) : 56 － 58．
2012, Vol. 29 
