非封闭式轨道交通直流牵引系统轨旁设备接地研究

城市轨道交通直流牵引系统中,由于用作回流的钢轨需考虑减少杂散电流泄漏而绝缘安装,非封闭区段架空接触网区域内的轨旁设备接地需特别注意,以避免故障情况下(如接触网断线)出现不可接受的电位导致人身电击事故。轨旁设备的接地需要考虑两方面因素,一是避免回流轨与轨旁设备(外露可导电体)的电位差超过标准规范允许值,二是需要考虑减少杂散电流,在两者无法兼顾时应优先考虑减小电位差。本文针对轨旁设备接地根据不同低压配电形式进行分析,并提出相应的措施建议。

Due to the rails used for current return of DC traction power supply system in urban rail transit are insulated installation(floating system)for the reason to reduce stray currents,attentions shall be paid on earthing of track side equipment(exposed conductive parts)which is placed within the overhead contact line zone(OCLZ)particularly in open track sections,in order to prevent impermissible effective tough voltage to put into risks of electric shock in fault conditions(e.g.broken overhead contact line).Two aspects should be taken into account:first,to avoid the potential difference between track side equipment and return rail exceeding the limited value as defined in relevant standards;second,reduction of stray currents shall also be considered.In case that both of the above mentioned aspects cannot be satisfied at the same time,priority should be given to reduction of the potential difference.This document puts forward different analysis and measures for different trackside equipment earthing according to different type of low voltage earthing systems.