根據電力設備試驗規程規定(ding)，100kVA以(yi)下的(de)變壓器接(jie)地(di)(di)(di)(di)(di)(di)點(dian)接(jie)地(di)(di)(di)(di)(di)(di)電(dian)(dian)(dian)阻(zu)(zu)不大于(yu)(yu)10Ω，100kVA以上的變壓器(qi)(qi)接(jie)地(di)(di)(di)(di)(di)(di)點(dian)接(jie)地(di)(di)(di)(di)(di)(di)電(dian)(dian)(dian)阻(zu)(zu)不大于(yu)(yu)4Ω。但由于(yu)(yu)設計(ji)施工技術的過(guo)失或外力(li)的破(po)壞，常常導致變壓器(qi)(qi)接(jie)地(di)(di)(di)(di)(di)(di)點(dian)接(jie)地(di)(di)(di)(di)(di)(di)電(dian)(dian)(dian)阻(zu)(zu)升高和接(jie)地(di)(di)(di)(di)(di)(di)線(xian)斷線(xian)故障發生，造成(cheng)供(gong)電(dian)(dian)(dian)異常，用戶電(dian)(dian)(dian)器(qi)(qi)設備燒毀，給供(gong)電(dian)(dian)(dian)單位的運行管理帶來一定困(kun)難。為此我們必須采取一定的措施，預防變壓器(qi)(qi)中性線(xian)與接(jie)地(di)(di)(di)(di)(di)(di)線(xian)斷線(xian)和接(jie)地(di)(di)(di)(di)(di)(di)電(dian)(dian)(dian)阻(zu)(zu)升高造成(cheng)的危(wei)害。

 1、變壓器接(jie)地線(xian)(xian)和中性線(xian)(xian)斷線(xian)(xian)及(ji)接(jie)地電阻升高的(de)原因

(1)由于接地(di)(di)體(ti)埋設不規范，安裝工藝馬虎，接地(di)(di)體(ti)與(yu)接地(di)(di)線接頭松(song)動，大地(di)(di)過(guo)于干(gan)燥(zao)等，均有(you)可能(neng)造成接地(di)(di)電阻的升(sheng)高。

(2)由(you)于變(bian)壓器設計(ji)安裝時，對接地(di)線的作用及重要性(xing)認識不足，中性(xing)線截面選擇過小(xiao)，當三相負荷(he)不平衡(heng)時，中性(xing)線電流過大而導致燒斷。另外(wai)由(you)于外(wai)力的破壞或(huo)接地(di)線被盜(dao)等原因都有可能導致接地(di)線或(huo)中性(xing)線斷線。

 2、升高的現象及危(wei)害

(1)變(bian)壓(ya)(ya)器(qi)接(jie)(jie)地(di)(di)(di)(di)線接(jie)(jie)地(di)(di)(di)(di)電(dian)(dian)(dian)(dian)阻(zu)(zu)升高(gao)，同(tong)時(shi)伴有(you)(you)相(xiang)(xiang)(xiang)(xiang)線絕(jue)緣(yuan)損壞而(er)接(jie)(jie)地(di)(di)(di)(di)，例(li)如(ru)，B相(xiang)(xiang)(xiang)(xiang)接(jie)(jie)地(di)(di)(di)(di)，這(zhe)時(shi)變(bian)壓(ya)(ya)器(qi)接(jie)(jie)地(di)(di)(di)(di)線中(zhong)(zhong)將(jiang)(jiang)(jiang)有(you)(you)一(yi)個電(dian)(dian)(dian)(dian)流流過，B相(xiang)(xiang)(xiang)(xiang)電(dian)(dian)(dian)(dian)壓(ya)(ya)加(jia)在(zai)大(da)(da)(da)(da)(da)地(di)(di)(di)(di)和(he)接(jie)(jie)地(di)(di)(di)(di)電(dian)(dian)(dian)(dian)阻(zu)(zu)上(shang)(shang)，當接(jie)(jie)地(di)(di)(di)(di)電(dian)(dian)(dian)(dian)阻(zu)(zu)越大(da)(da)(da)(da)(da)，那(nei)么接(jie)(jie)地(di)(di)(di)(di)電(dian)(dian)(dian)(dian)阻(zu)(zu)上(shang)(shang)的分壓(ya)(ya)就(jiu)越大(da)(da)(da)(da)(da)。這(zhe)時(shi)，如(ru)果有(you)(you)人(ren)(ren)誤(wu)觸(chu)變(bian)壓(ya)(ya)器(qi)接(jie)(jie)地(di)(di)(di)(di)線或(huo)中(zhong)(zhong)性(xing)線以及變(bian)壓(ya)(ya)器(qi)外(wai)殼(ke)(ke)，人(ren)(ren)體將(jiang)(jiang)(jiang)和(he)接(jie)(jie)地(di)(di)(di)(di)電(dian)(dian)(dian)(dian)阻(zu)(zu)形成并聯，如(ru)果接(jie)(jie)地(di)(di)(di)(di)電(dian)(dian)(dian)(dian)阻(zu)(zu)足夠大(da)(da)(da)(da)(da)，那(nei)么加(jia)在(zai)人(ren)(ren)體上(shang)(shang)的電(dian)(dian)(dian)(dian)壓(ya)(ya)就(jiu)會很高(gao)，導(dao)致(zhi)人(ren)(ren)觸(chu)電(dian)(dian)(dian)(dian)。如(ru)果人(ren)(ren)體誤(wu)觸(chu)A相(xiang)(xiang)(xiang)(xiang)或(huo)C相(xiang)(xiang)(xiang)(xiang)，加(jia)在(zai)人(ren)(ren)體上(shang)(shang)的電(dian)(dian)(dian)(dian)壓(ya)(ya)將(jiang)(jiang)(jiang)是線電(dian)(dian)(dian)(dian)壓(ya)(ya)380V，那(nei)么對(dui)人(ren)(ren)身安全將(jiang)(jiang)(jiang)造成更大(da)(da)(da)(da)(da)的威脅。另外(wai)，由于(yu)有(you)(you)的用(yong)(yong)戶將(jiang)(jiang)(jiang)變(bian)壓(ya)(ya)器(qi)中(zhong)(zhong)性(xing)線與用(yong)(yong)電(dian)(dian)(dian)(dian)設(she)(she)備(bei)外(wai)殼(ke)(ke)相(xiang)(xiang)(xiang)(xiang)連(lian)，作(zuo)保(bao)護接(jie)(jie)地(di)(di)(di)(di)用(yong)(yong)，而(er)設(she)(she)備(bei)又不對(dui)地(di)(di)(di)(di)絕(jue)緣(yuan)。當B相(xiang)(xiang)(xiang)(xiang)接(jie)(jie)地(di)(di)(di)(di)，大(da)(da)(da)(da)(da)地(di)(di)(di)(di)就(jiu)和(he)B相(xiang)(xiang)(xiang)(xiang)等電(dian)(dian)(dian)(dian)位，相(xiang)(xiang)(xiang)(xiang)電(dian)(dian)(dian)(dian)壓(ya)(ya)就(jiu)加(jia)于(yu)大(da)(da)(da)(da)(da)地(di)(di)(di)(di)和(he)中(zhong)(zhong)性(xing)線之間，這(zhe)時(shi)用(yong)(yong)電(dian)(dian)(dian)(dian)設(she)(she)備(bei)如(ru)取用(yong)(yong)A相(xiang)(xiang)(xiang)(xiang)或(huo)C相(xiang)(xiang)(xiang)(xiang)電(dian)(dian)(dian)(dian)源，外(wai)殼(ke)(ke)對(dui)地(di)(di)(di)(di)電(dian)(dian)(dian)(dian)壓(ya)(ya)將(jiang)(jiang)(jiang)升高(gao)到220V，設(she)(she)備(bei)相(xiang)(xiang)(xiang)(xiang)對(dui)地(di)(di)(di)(di)電(dian)(dian)(dian)(dian)壓(ya)(ya)將(jiang)(jiang)(jiang)為380V。這(zhe)時(shi)人(ren)(ren)如(ru)果接(jie)(jie)觸(chu)用(yong)(yong)電(dian)(dian)(dian)(dian)設(she)(she)備(bei)外(wai)殼(ke)(ke)，同(tong)樣會引起觸(chu)電(dian)(dian)(dian)(dian)。另外(wai)，B相(xiang)(xiang)(xiang)(xiang)接(jie)(jie)地(di)(di)(di)(di)時(shi)，將(jiang)(jiang)(jiang)有(you)(you)一(yi)個電(dian)(dian)(dian)(dian)流從大(da)(da)(da)(da)(da)地(di)(di)(di)(di)流入(ru)機殼(ke)(ke)回到中(zhong)(zhong)性(xing)線，對(dui)于(yu)有(you)(you)的要求(qiu)較高(gao)的用(yong)(yong)電(dian)(dian)(dian)(dian)設(she)(she)備(bei)將(jiang)(jiang)(jiang)無法運(yun)行。

(2)接(jie)(jie)(jie)地線(xian)(xian)斷(duan)線(xian)(xian)，變壓器附近接(jie)(jie)(jie)地線(xian)(xian)斷(duan)線(xian)(xian)，就(jiu)猶如(ru)接(jie)(jie)(jie)地電阻升(sheng)高到無窮(qiong)大，這(zhe)時的大地電位就(jiu)是(shi)接(jie)(jie)(jie)地相電位，一切現(xian)象就(jiu)同接(jie)(jie)(jie)地電阻升(sheng)高時一樣，只是(shi)危害更(geng)大，這(zhe)里不再(zai)重述(shu)。

(3)當三相四線供電(dian)(dian)變壓器中性(xing)線斷(duan)線時，此時由(you)于三相負載的(de)不平(ping)衡(heng)，負載接地(di)(di)點將發生偏(pian)移，接地(di)(di)點電(dian)(dian)位不為(wei)零，使得有的(de)相電(dian)(dian)壓升高，燒毀(hui)用電(dian)(dian)設備。

當接(jie)地線斷(duan)線或(huo)(huo)接(jie)地電(dian)阻(zu)升高(gao)時(shi)(shi)，由(you)于變(bian)壓(ya)器(qi)避(bi)(bi)雷(lei)器(qi)接(jie)地線斷(duan)開(kai)或(huo)(huo)接(jie)地電(dian)阻(zu)升高(gao)。雷(lei)擊過電(dian)壓(ya)時(shi)(shi)，避(bi)(bi)雷(lei)器(qi)不(bu)能正常對地放電(dian)，致使避(bi)(bi)雷(lei)器(qi)或(huo)(huo)變(bian)壓(ya)器(qi)損壞。

 3、預(yu)防措施

(1)嚴格施(shi)工工藝，規范接(jie)地(di)體的埋設。按規程(cheng)選(xuan)取(qu)接(jie)地(di)線(xian)的截面及(ji)種類，正確選(xuan)取(qu)中性線(xian)截面積。

(2)在用(yong)(yong)戶(hu)(hu)電(dian)能表后(hou)裝設剩余電(dian)流(liu)動(dong)作保(bao)(bao)(bao)護器(qi)(qi)(qi)。當(dang)我(wo)們在用(yong)(yong)戶(hu)(hu)裝設了保(bao)(bao)(bao)護器(qi)(qi)(qi)后(hou)，如(ru)果(guo)用(yong)(yong)戶(hu)(hu)后(hou)的(de)導線(xian)或(huo)用(yong)(yong)電(dian)設備絕緣損壞(huai)，形成對(dui)地(di)(di)(di)放(fang)電(dian)。此時如(ru)果(guo)變壓器(qi)(qi)(qi)接地(di)(di)(di)點接地(di)(di)(di)電(dian)阻過高，大(da)地(di)(di)(di)電(dian)位將不再為零，這(zhe)時將有(you)一(yi)個電(dian)流(liu)經保(bao)(bao)(bao)護器(qi)(qi)(qi)、大(da)地(di)(di)(di)流(liu)入變壓器(qi)(qi)(qi)接地(di)(di)(di)點，此電(dian)流(liu)將使保(bao)(bao)(bao)護器(qi)(qi)(qi)動(dong)作，而將接地(di)(di)(di)點切除，防止了大(da)地(di)(di)(di)電(dian)位的(de)升高。另外(wai)，加裝保(bao)(bao)(bao)護器(qi)(qi)(qi)后(hou)，當(dang)人接觸相線(xian)時，保(bao)(bao)(bao)護器(qi)(qi)(qi)也會動(dong)作，從而保(bao)(bao)(bao)障了人員的(de)人身安全。

(3)在變壓器的(de)(de)(de)中(zhong)性(xing)(xing)線上選取適當的(de)(de)(de)位(wei)置(zhi)將變壓(ya)器的(de)(de)(de)中(zhong)性(xing)(xing)線多(duo)點(dian)(dian)(dian)重(zhong)復(fu)接(jie)(jie)地(di)(di)。當變壓(ya)器中(zhong)性(xing)(xing)線在某點(dian)(dian)(dian)斷線時，由于多(duo)點(dian)(dian)(dian)接(jie)(jie)地(di)(di)，中(zhong)性(xing)(xing)線電(dian)流仍可經大地(di)(di)回到(dao)變壓(ya)器中(zhong)性(xing)(xing)點(dian)(dian)(dian)，中(zhong)性(xing)(xing)線的(de)(de)(de)電(dian)位(wei)始終為零(ling)，每相負載的(de)(de)(de)電(dian)壓(ya)始終為正常(chang)的(de)(de)(de)相電(dian)壓(ya)。另一(yi)方面，當變壓(ya)器接(jie)(jie)地(di)(di)點(dian)(dian)(dian)接(jie)(jie)地(di)(di)電(dian)阻升高或(huo)接(jie)(jie)地(di)(di)線斷線相線接(jie)(jie)地(di)(di)，由于有了多(duo)點(dian)(dian)(dian)的(de)(de)(de)重(zhong)復(fu)接(jie)(jie)地(di)(di)，也能保(bao)證大地(di)(di)的(de)(de)(de)電(dian)位(wei)為零(ling)，不會對人生安全和設備(bei)的(de)(de)(de)正常(chang)運(yun)行造(zao)成(cheng)威脅(xie)。

在采取以(yi)上防范措(cuo)施(shi)的同時，也(ye)要加強(qiang)對廣大人民群眾(zhong)進行電(dian)力法規的廣泛(fan)宣傳(chuan)，讓更(geng)多的人來關(guan)心電(dian)力設施(shi)。一經發現設備障礙，能(neng)及時向供電(dian)部門反映，以(yi)求(qiu)盡快將電(dian)力設備故障消(xiao)滅在萌芽狀態，確保安(an)全(quan)可(ke)靠地供電(dian)。