在大短路電流接地係統中發生接地故障後，就有零序電流、零序電壓和零序功率出現
，利用這些電氣量構成保護接地短路的繼電保護裝置統稱為零序保護。

 

 

三相電流平衡時，沒有零序電流，不平衡時產生零序電流
，零序保護就是用零序互感器采集零序電流，當零序電流超過一定值（綜合保護中設定）
，綜合保護接觸器吸合，斷開電路。零序電流互感器內穿過三根相線矢量。

 

正常情況下，三根線的向量和為零，零序電流互感器無零序電流。當人體觸電或者其他漏電情況下：三根線的向量和不為零，零序電流互感器有零序電流，一旦達到設定值，則保護動作跳閘。

 

1. 多台變壓器同時運行
，隻需要1-2台接地運行；

 

若不止一台變壓器時，運行方式往往隻允許1-2taijiediyunxing，shejicaiyongzhongxingdianlingxudianliujidianqiyujingxianglinbianyaqizhongxingdianlingxudianliujidianqikongzhidelingxudianyajidianqipeiheshiyongdebianyaqibaohufangan
，baohuhuilushejixiantiaozhongxingdianbujiedibianyaqi

，ranhouzhongxingdiantiaozhijiejiedidebianyaqi，yifangzhibujiedixitongguzhangdiandejianxiexinghuguangguodianyaweijidianqishebeideanquan。weibimianquanchangsuoyoubianyaqiquanbubeiqiedeyanzhonghouguo
，baohushijianyingzhujipeihe
，xianduankaimulianhuofenduanluqi，zaijinglingxudianyayuanjiantiaokaizhongxindianbujiedizhubian，zuihoujinglingxudianliuyuanjiantiaokaizhongxingdianjiedizhubian。

 

2. 變壓器中點有可能接地運行；

 

對(dui)中(zhong)性(xing)點(dian)有(you)可(ke)能(neng)直(zhi)接(jie)接(jie)地(di)運(yun)行(xing)，也(ye)有(you)可(ke)能(neng)不(bu)接(jie)地(di)運(yun)行(xing)的(de)主(zhu)變(bian)，因(yin)失(shi)去(qu)接(jie)地(di)中(zhong)性(xing)點(dian)引(yin)起(qi)的(de)電(dian)壓(ya)升(sheng)高(gao)，應(ying)裝(zhuang)設(she)相(xiang)應(ying)的(de)保(bao)護(hu)裝(zhuang)置(zhi)。在(zai)直(zhi)接(jie)接(jie)地(di)時(shi)用(yong)零(ling)序(xu)電(dian)流(liu)保(bao)護(hu)。在(zai)中(zhong)性(xing)點(dian)不(bu)接(jie)地(di)時(shi)用(yong)零(ling)序(xu)電(dian)壓(ya)保(bao)護(hu)或(huo)裝(zhuang)設(she)放(fang)電(dian)間(jian)隙(xi)保(bao)護(hu)，放(fang)到(dao)間(jian)隙(xi)保(bao)護(hu)起(qi)到(dao)過(guo)電(dian)壓(ya)保(bao)護(hu)的(de)作(zuo)用(yong)，當(dang)放(fang)電(dian)間(jian)隙(xi)被(bei)擊(ji)穿(chuan)形(xing)成(cheng)零(ling)序(xu)電(dian)流(liu)通(tong)路(lu)時(shi)
，利(li)用(yong)接(jie)在(zai)放(fang)電(dian)間(jian)隙(xi)回(hui)路(lu)的(de)零(ling)序(xu)電(dian)流(liu)保(bao)護(hu)，切(qie)除(chu)該(gai)變(bian)壓(ya)器(qi)。變(bian)壓(ya)器(qi)采(cai)用(yong)放(fang)電(dian)間(jian)隙(xi)保(bao)護(hu)

，放(fang)電(dian)間(jian)隙(xi)裝(zhuang)於(yu)變(bian)壓(ya)器(qi)中(zhong)性(xing)點(dian)與(yu)地(di)線(xian)之(zhi)間(jian)、有棒形

、球形、jiaoxingdengduozhongxingshi，shijianzhuangzhongkeyibangxingyongdezuiduo，lingxudianyabaohudongzuodianyaanfashengdanxiangjiediguzhangshibaohuanzhuangchukenengchuxianzuidalingxudianyazhengding。

 

3. 變壓器高壓側中性點直接接地運行

 

對變壓器高壓側中性點直接接地的自耦變壓器和三繞組變壓器采用零序過電流保護

，取自變壓器中性點的零序CT安裝無方向零序保護，在主變兩側分別裝上零序保護，了為滿足選擇性可增設零序方向元件。方向元件用各斷路器側CTdezichanlingxudianliu。zhubianzhongxingdianlingxudianliuhuganqidejixingjiexiankeyijiangzhongxingdianlingxudianliubaohuzhixiangbencemuxianhuozhubiance。caiyongduanluqichudelingxudianliubaohu，heyibangaozhongyacefangxiangzhixianggezidemuxian，dandangzhongyacebuwuyuanshi，gaoyacelingxufangxiangkezhixiangzhubian。zhixiangmuxianbaohudefanweiyiweiduanluqidianliuhuganqianzhuangchukaishi，xuyaoyuxianlulingxubaohupeihe。zhixiangzhubianbianyaqi，xuyaozhubianyaqilingyicechuxiandejiedibaohuxiangpeihe。caiyongzhubianzhongxingdianchudilingxudianliubaohu，zebaohufanweibiduanluqichulingxudianliubaohubiyaokuanyixie。xiaolangdimuqianyunxingdezhubianzhongxingdianlingxudianliubaohuwufangxiang
，zheyangdezhengdingpeihebijiaoqingxifangbian，yishixianzhitiaokaimulianduanluqi，ershixianzhitiaokaibencekaiguan。