一、小电流选线简介 A brief introduction to small current selection 小电流选线全称小电流接地选线装置，简称小电流，小电流选线，小电流短路选线系统，是一种电力行业使用的保护设备。该设备适用于3kV－66kV中性点不接地或中性点经电阻、消弧线圈接地系统的单相接地选线，用于电力系统的变电站、发电厂、水电站及化工、采油、冶金、煤炭、铁路等大型厂矿企业的供电系统，能够指示出发生单相接地故障的线路。 Small current line selection for small current grounding line selection device, referred to as "low current, low current line selection, small short circuit current line selection system, the protection of the use of the electric power industry is a kind of equipment. The equipment is suitable for 3 kv, 66 kv neutral point grounding or neutral resistance, arc suppression coil grounding system of single phase grounding line selection, used in power system transformer substation, power plants, hydropower and chemical, oil, metallurgical, coal, rail, power supply system of large industrial enterprises, such as to indicate the single-phase earth fault line. 二、小电流系统单相接地的特点 Two, the characteristic of single phase ground of small current system 1. 选线装置实时采集系统故障信号，应用多种选线方法进行综合选线，具体包括：智能群体比幅比相法、谐波比幅比相法、小波法、首半波法、有功分量法、能量法、零序电流突变量法。 1. The line selection device real-time fault signal acquisition system, a variety of line selection method is applied to synthetically line selection, specific include: intelligent group than picture than phase method, harmonic amplitude phase method, the wavelet method, the first half wave method, active component method, energy method, method of zero sequence current mutation. 2. 装置具有故障录波功能，可以提供故障前后的波形，包括故障发生前的一个周期和故障发生后五个周期的波形。可保存现场故障录波数据和选线结果20000次。 2. The device has the function of fault wave record, can provide before and after the fault waveform, including failure occurs before a cycle and failure after five cycles of waveform. Can save the field fault record wave data and the result of the selected line 20,000 times. 3. 装置具备跳闸功能，大容量触点可以直接接入跳闸回路，实现选线后的故障切除。也可与自动重合闸结合，实现选线后的自动消弧和进一步确认(可选功能)。 The device has the function of tripping, and the large capacity contact can be connected directly to the tripping circuit, which can be removed after the selection line. It can also be combined with auto reclosing to realize automatic arc suppression and further confirmation (optional feature) after selecting line. 4. 装置具备消谐功能，能够消除1/3分频、1/2分频、基频、3倍频、5倍频的铁磁谐振(可选功能)。 The device has an anti-harmonic function which can eliminate 1/3 frequency, 1/2 sub-frequency, base frequency, 3 times frequency, 5 times frequency of ferromagnetic resonance (optional).