變壓器是電網變換電壓和傳送電能的電氣設備，是電網向用戶供電的載體，變壓器的a全可靠運行情系萬家燈火。然而在電網運行中由于諸多原因會產生過電壓，而變壓器的絕緣水平相對比較薄弱，在變壓器損壞的原因中，過電壓造成損壞的概率Z大。在電網運行中因某種原因產生過電壓，必將導致變壓器的損壞，其絕緣水平主要由雷電擊耐受電壓和工頻耐受電壓來決定。

　　過(guo)電(dian)壓(ya)(ya)系指(zhi)對絕(jue)緣有危險的(de)(de)突然電(dian)壓(ya)(ya)升高(gao)，這種非正常(chang)的(de)(de)電(dian)壓(ya)(ya)升高(gao)，其幅值(zhi)可達(da)設備(bei)額(e)定(ding)電(dian)壓(ya)(ya)的(de)(de)幾倍以(yi)上，嚴重威(wei)脅(xie)變(bian)壓(ya)(ya)器(qi)絕(jue)緣的(de)(de)a全(quan)，若過(guo)電(dian)壓(ya)(ya)持續時間較長(chang)，必將造成變(bian)壓(ya)(ya)器(qi)的(de)(de)損壞(huai)。為確保電(dian)網運行中變(bian)壓(ya)(ya)器(qi)的(de)(de)a全(quan)，除選用(yong)變(bian)壓(ya)(ya)器(qi)外，還要對變(bian)壓(ya)(ya)器(qi)設置合(he)理的(de)(de)過(guo)電(dian)壓(ya)(ya)保護措施。

　　一、電(dian)網過電(dian)壓產生的機理

　　電(dian)(dian)(dian)(dian)(dian)(dian)(dian)力系(xi)統的過(guo)(guo)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)一(yi)般可分(fen)為(wei)暫時過(guo)(guo)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(工頻過(guo)(guo)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)、諧(xie)(xie)(xie)振(zhen)過(guo)(guo)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)、弧光(guang)接地(di)過(guo)(guo)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya))、操作過(guo)(guo)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)、雷電(dian)(dian)(dian)(dian)(dian)(dian)(dian)過(guo)(guo)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)等。暫時過(guo)(guo)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)主要由(you)單相(xiang)接地(di)故(gu)障、諧(xie)(xie)(xie)振(zhen)等引(yin)(yin)起(qi)的。諧(xie)(xie)(xie)振(zhen)過(guo)(guo)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)是(shi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)網(wang)中電(dian)(dian)(dian)(dian)(dian)(dian)(dian)氣設備(bei)發生(sheng)故(gu)障，或(huo)頻繁操作設備(bei)引(yin)(yin)起(qi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)網(wang)中電(dian)(dian)(dian)(dian)(dian)(dian)(dian)感和(he)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)容(rong)匹配而構(gou)成諧(xie)(xie)(xie)振(zhen)回(hui)路，在條件 下產生(sheng)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)能、磁能轉換而引(yin)(yin)起(qi)的過(guo)(guo)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)，如(ru)是(shi)變壓(ya)(ya)(ya)器的勵磁電(dian)(dian)(dian)(dian)(dian)(dian)(dian)感和(he)對(dui)地(di)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)容(rong)產生(sheng)的鐵(tie)磁諧(xie)(xie)(xie)振(zhen)，其(qi)引(yin)(yin)起(qi)的過(guo)(guo)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)會更高。弧光(guang)接地(di)過(guo)(guo)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)系(xi)因系(xi)統發生(sheng)單相(xiang)接地(di)故(gu)障，在接地(di)點因弧光(guang)放電(dian)(dian)(dian)(dian)(dian)(dian)(dian)而引(yin)(yin)起(qi)的過(guo)(guo)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)。

　　操作過電(dian)壓系因電(dian)網狀態的(de)突(tu)變而(er)引起電(dian)磁場 的(de)急劇(ju)變化，或投切大容量(liang)設(she)備，或是(shi)對(dui)設(she)備的(de)操作失(shi)誤等而(er)引起 快速(su)釋放時產生的(de)過電(dian)壓。主要表現在(zai)空(kong)載線路、變壓器的(de)開斷和(he)重合閘(zha)等。

　　雷(lei)電(dian)(dian)(dian)(dian)過(guo)電(dian)(dian)(dian)(dian)壓(ya)是(shi)大氣中帶有大量正電(dian)(dian)(dian)(dian)荷雷(lei)云(yun)與帶負電(dian)(dian)(dian)(dian)荷雷(lei)云(yun)相遇時，發(fa)生(sheng)雷(lei)云(yun)放(fang)(fang)電(dian)(dian)(dian)(dian)而(er)引(yin)起(qi)的過(guo)電(dian)(dian)(dian)(dian)壓(ya)。雷(lei)電(dian)(dian)(dian)(dian)過(guo)電(dian)(dian)(dian)(dian)壓(ya)可分為(wei)直(zhi)(zhi)擊雷(lei)過(guo)電(dian)(dian)(dian)(dian)壓(ya)和感應(ying)過(guo)電(dian)(dian)(dian)(dian)壓(ya)。直(zhi)(zhi)接雷(lei)過(guo)電(dian)(dian)(dian)(dian)壓(ya)是(shi)雷(lei)云(yun)直(zhi)(zhi)接對設(she)備(bei)、構件等導體的放(fang)(fang)電(dian)(dian)(dian)(dian)產生(sheng)的，而(er)感應(ying)過(guo)電(dian)(dian)(dian)(dian)壓(ya)則(ze)是(shi)電(dian)(dian)(dian)(dian)磁場的急(ji)劇(ju)變化(hua)而(er)產生(sheng)的。

　　二、電網過電壓對變壓器(qi)的危害

　　電(dian)(dian)網中產生的(de)(de)(de)幾(ji)種過(guo)電(dian)(dian)壓(ya)(ya)，真正對變壓(ya)(ya)器絕緣(yuan)和(he)保護裝置(zhi)產生影響(xiang)的(de)(de)(de)，主要取決于(yu)過(guo)電(dian)(dian)壓(ya)(ya)的(de)(de)(de)波(bo)形。幅值和(he)持(chi)續(xu)時間。考核設備(bei)絕緣(yuan)水平(ping)的(de)(de)(de)電(dian)(dian)壓(ya)(ya)波(bo)形有(you)三種：短(duan)波(bo)前(qian)的(de)(de)(de)雷電(dian)(dian)波(bo)、長波(bo)前(qian)的(de)(de)(de)操(cao)作(zuo)波(bo)和(he)低頻(pin)電(dian)(dian)壓(ya)(ya)波(bo)。設備(bei)絕緣(yuan)對雷電(dian)(dian)、操(cao)作(zuo)或工頻(pin)電(dian)(dian)壓(ya)(ya)的(de)(de)(de)耐受能(neng)力應由相應的(de)(de)(de)波(bo)形電(dian)(dian)壓(ya)(ya)來檢(jian)驗。

　　在過電(dian)壓(ya)(ya)(ya)(ya)(ya)(ya)對變(bian)壓(ya)(ya)(ya)(ya)(ya)(ya)器(qi)(qi)(qi)造(zao)成(cheng)損(sun)壞的事故中，雷(lei)電(dian)過電(dian)壓(ya)(ya)(ya)(ya)(ya)(ya)導致絕緣(yuan)擊穿損(sun)壞的機率Z多(duo)。當電(dian)網(wang)遭受(shou)雷(lei)擊時(shi)，在線(xian)路(lu)(lu)導線(xian)上會(hui)產生一種振幅很大，作(zuo)用(yong)時(shi)間很短的非周期性脈沖電(dian)壓(ya)(ya)(ya)(ya)(ya)(ya)波，它以光速沿線(xian)傳輸，先在線(xian)路(lu)(lu)避雷(lei)器(qi)(qi)(qi)放(fang)電(dian)，余波經(jing)變(bian)壓(ya)(ya)(ya)(ya)(ya)(ya)器(qi)(qi)(qi)入地，當余波經(jing)變(bian)壓(ya)(ya)(ya)(ya)(ya)(ya)器(qi)(qi)(qi)保(bao)護的避雷(lei)器(qi)(qi)(qi)時(shi)，將產生電(dian)壓(ya)(ya)(ya)(ya)(ya)(ya)降(殘(can)壓(ya)(ya)(ya)(ya)(ya)(ya))而(er)作(zuo)用(yong)在變(bian)壓(ya)(ya)(ya)(ya)(ya)(ya)器(qi)(qi)(qi)上。假如變(bian)壓(ya)(ya)(ya)(ya)(ya)(ya)器(qi)(qi)(qi)與避雷(lei)器(qi)(qi)(qi)之間存在電(dian)氣距離，殘(can)壓(ya)(ya)(ya)(ya)(ya)(ya)在進(jin)入前會(hui)在這段距離的導線(xian)振蕩(dang)而(er)導致電(dian)壓(ya)(ya)(ya)(ya)(ya)(ya)的升(sheng)高，造(zao)成(cheng)加在變(bian)壓(ya)(ya)(ya)(ya)(ya)(ya)器(qi)(qi)(qi)上電(dian)壓(ya)(ya)(ya)(ya)(ya)(ya)高于(yu)殘(can)壓(ya)(ya)(ya)(ya)(ya)(ya)，從而(er)對變(bian)壓(ya)(ya)(ya)(ya)(ya)(ya)器(qi)(qi)(qi)絕緣(yuan)a全造(zao)成(cheng)威脅(xie)。所以在安裝(zhuang)變(bian)壓(ya)(ya)(ya)(ya)(ya)(ya)器(qi)(qi)(qi)的保(bao)護避雷(lei)器(qi)(qi)(qi)時(shi)，應盡量實現避雷(lei)器(qi)(qi)(qi)和變(bian)壓(ya)(ya)(ya)(ya)(ya)(ya)器(qi)(qi)(qi)保(bao)持零·距離。

　　電(dian)網內出現(xian)的諧(xie)振過電(dian)壓或操(cao)作過電(dian)壓，其過電(dian)壓幅值也高，持(chi)續時間(jian)也較長(chang)。同樣也會威(wei)脅到變壓器運(yun)行(xing)的a全(quan)，甚至(zhi)還會導致絕緣擊穿而(er)毀壞變壓器。

　　此(ci)外，逆(ni)變(bian)換過(guo)(guo)電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)(ya)對(dui)變(bian)壓(ya)(ya)(ya)(ya)(ya)(ya)器(qi)(qi)的危(wei)害也(ye)(ye)(ye)不容忽視。當(dang)變(bian)壓(ya)(ya)(ya)(ya)(ya)(ya)器(qi)(qi)采用避雷(lei)(lei)器(qi)(qi)進行防雷(lei)(lei)保(bao)護時(shi)，其(qi)避雷(lei)(lei)器(qi)(qi)接(jie)(jie)地(di)線(xian)、變(bian)壓(ya)(ya)(ya)(ya)(ya)(ya)器(qi)(qi)中(zhong)性線(xian)和變(bian)壓(ya)(ya)(ya)(ya)(ya)(ya)器(qi)(qi)外殼采用"三位一(yi)(yi)體"的方式接(jie)(jie)地(di)。變(bian)壓(ya)(ya)(ya)(ya)(ya)(ya)器(qi)(qi)運行中(zhong)若高(gao)壓(ya)(ya)(ya)(ya)(ya)(ya)側遭受雷(lei)(lei)擊(ji)時(shi)，會引起避雷(lei)(lei)器(qi)(qi)放(fang)(fang)電(dian)(dian)(dian)(dian)(dian)，產(chan)生(sheng)(sheng)的殘壓(ya)(ya)(ya)(ya)(ya)(ya)作用在高(gao)壓(ya)(ya)(ya)(ya)(ya)(ya)繞(rao)(rao)組(zu)上(shang)。由(you)于(yu)高(gao)壓(ya)(ya)(ya)(ya)(ya)(ya)繞(rao)(rao)組(zu)阻(zu)抗很(hen)大(da)，容抗很(hen)小，雷(lei)(lei)電(dian)(dian)(dian)(dian)(dian)流只在高(gao)壓(ya)(ya)(ya)(ya)(ya)(ya)繞(rao)(rao)組(zu)和對(dui)地(di)電(dian)(dian)(dian)(dian)(dian)容上(shang)·流過(guo)(guo)，其(qi)電(dian)(dian)(dian)(dian)(dian)路經(jing)接(jie)(jie)地(di)點放(fang)(fang)電(dian)(dian)(dian)(dian)(dian)時(shi)，會在接(jie)(jie)地(di)電(dian)(dian)(dian)(dian)(dian)阻(zu)上(shang)產(chan)生(sheng)(sheng)一(yi)(yi)個很(hen)大(da)的沖擊(ji)電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)(ya)降(jiang)，此(ci)電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)(ya)經(jing)過(guo)(guo)中(zhong)性線(xian)也(ye)(ye)(ye)會施加低(di)壓(ya)(ya)(ya)(ya)(ya)(ya)繞(rao)(rao)組(zu)上(shang)，而低(di)壓(ya)(ya)(ya)(ya)(ya)(ya)繞(rao)(rao)組(zu)流過(guo)(guo)雷(lei)(lei)電(dian)(dian)(dian)(dian)(dian)流也(ye)(ye)(ye)會產(chan)生(sheng)(sheng)磁(ci)通。根據電(dian)(dian)(dian)(dian)(dian)磁(ci)感應(ying)原理，此(ci)磁(ci)通會在高(gao)壓(ya)(ya)(ya)(ya)(ya)(ya)繞(rao)(rao)組(zu)上(shang)按變(bian)壓(ya)(ya)(ya)(ya)(ya)(ya)器(qi)(qi)變(bian)化產(chan)生(sheng)(sheng)很(hen)高(gao)感應(ying)電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)(ya)，此(ci)電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)(ya)稱之為"逆(ni)變(bian)換過(guo)(guo)電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)(ya)"。該電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)(ya)幅值要比殘壓(ya)(ya)(ya)(ya)(ya)(ya)大(da)幾倍到幾十倍，同樣也(ye)(ye)(ye)會造成變(bian)壓(ya)(ya)(ya)(ya)(ya)(ya)器(qi)(qi)絕緣的擊(ji)穿而損壞。

　　三、電(dian)網過電(dian)壓的保護(hu)措施

　　1.裝(zhuang)設(she)避雷針保護(hu)

　　避(bi)(bi)雷(lei)(lei)針(zhen)(zhen)(zhen)能將雷(lei)(lei)電流引向(xiang)自身而a全入地(di)，是(shi)保(bao)(bao)護(hu)直擊(ji)雷(lei)(lei)的措施。變(bian)電所(suo)及(ji)電氣設(she)備(bei)一(yi)般采用(yong)(yong)避(bi)(bi)雷(lei)(lei)針(zhen)(zhen)(zhen)進行保(bao)(bao)護(hu)，其保(bao)(bao)護(hu)范圍取(qu)決于避(bi)(bi)雷(lei)(lei)針(zhen)(zhen)(zhen)高度與(yu)根數，若(ruo)采用(yong)(yong)多根避(bi)(bi)雷(lei)(lei)針(zhen)(zhen)(zhen)保(bao)(bao)護(hu)，其范圍更大效果(guo)好。同時，為避(bi)(bi)免反擊(ji)事故，避(bi)(bi)雷(lei)(lei)針(zhen)(zhen)(zhen)的接(jie)地(di)網(wang)設(she)置與(yu)接(jie)地(di)電阻值要(yao)符合技術規范，并使之與(yu)構(gou)架(jia)、變(bian)壓器(qi)、斷(duan)路器(qi)等設(she)備(bei)之間距離滿(man)足技術要(yao)求，才能取(qu)得良好的防雷(lei)(lei)保(bao)(bao)護(hu)效果(guo)。

　　2.架設避雷線進行保(bao)護

　　在變(bian)電(dian)(dian)(dian)所近區電(dian)(dian)(dian)源進(jin)線(xian)(xian)上(shang)方(fang)架(jia)設避(bi)(bi)雷(lei)(lei)(lei)線(xian)(xian)保(bao)護，可使(shi)電(dian)(dian)(dian)源進(jin)線(xian)(xian)遭受雷(lei)(lei)(lei)電(dian)(dian)(dian)侵(qin)入波的(de)(de)(de)概率大(da)大(da)減少。若在避(bi)(bi)雷(lei)(lei)(lei)線(xian)(xian)以外線(xian)(xian)路上(shang)落雷(lei)(lei)(lei)時(shi)，由于進(jin)線(xian)(xian)段導線(xian)(xian)本身阻抗(kang)作用(yong)，使(shi)流(liu)過避(bi)(bi)雷(lei)(lei)(lei)器的(de)(de)(de)雷(lei)(lei)(lei)電(dian)(dian)(dian)流(liu)受到限制，又由于導線(xian)(xian)上(shang)的(de)(de)(de)沖(chong)擊電(dian)(dian)(dian)暈的(de)(de)(de)影響，使(shi)雷(lei)(lei)(lei)電(dian)(dian)(dian)侵(qin)入波的(de)(de)(de)陡度和幅值下降(jiang)(jiang)，從而(er)使(shi)保(bao)護變(bian)壓(ya)(ya)器的(de)(de)(de)避(bi)(bi)雷(lei)(lei)(lei)器動作殘壓(ya)(ya)降(jiang)(jiang)低，有(you)利于與變(bian)壓(ya)(ya)器絕緣(yuan)的(de)(de)(de)配合，因(yin)而(er)對變(bian)壓(ya)(ya)器的(de)(de)(de)防雷(lei)(lei)(lei)起到起良好作用(yong)。

　　3.裝設避雷(lei)器進行保護(hu)

　　電(dian)(dian)(dian)網保護過(guo)(guo)電(dian)(dian)(dian)壓(ya)(ya)的(de)(de)避(bi)雷(lei)(lei)器(qi)(qi)(qi)，無(wu)論是無(wu)間(jian)隙的(de)(de)氧化鋅避(bi)雷(lei)(lei)器(qi)(qi)(qi)，還是有(you)間(jian)隙的(de)(de)普(pu)通閥式避(bi)雷(lei)(lei)器(qi)(qi)(qi)，器(qi)(qi)(qi)選(xuan)擇使(shi)用的(de)(de)一(yi)個共同原則是：避(bi)雷(lei)(lei)器(qi)(qi)(qi)的(de)(de)額定(ding)電(dian)(dian)(dian)壓(ya)(ya)應不低于避(bi)雷(lei)(lei)器(qi)(qi)(qi)安裝(zhuang)地點的(de)(de)暫時(shi)過(guo)(guo)電(dian)(dian)(dian)壓(ya)(ya);變(bian)壓(ya)(ya)器(qi)(qi)(qi)中性(xing)點避(bi)雷(lei)(lei)器(qi)(qi)(qi)的(de)(de)額定(ding)電(dian)(dian)(dian)壓(ya)(ya)應不低于變(bian)壓(ya)(ya)器(qi)(qi)(qi)的(de)(de)Z高相(xiang)電(dian)(dian)(dian)壓(ya)(ya)。若(ruo)避(bi)雷(lei)(lei)器(qi)(qi)(qi)的(de)(de)額定(ding)電(dian)(dian)(dian)壓(ya)(ya)選(xuan)低了，對(dui)閥式避(bi)雷(lei)(lei)器(qi)(qi)(qi)而(er)(er)言，若(ruo)線(xian)路(lu)發生單(dan)相(xiang)接地故(gu)障時(shi)，由于變(bian)壓(ya)(ya)中性(xing)點出現過(guo)(guo)電(dian)(dian)(dian)壓(ya)(ya)而(er)(er)無(wu)法滅弧造成爆炸;對(dui)無(wu)間(jian)隙氧化鋅避(bi)雷(lei)(lei)器(qi)(qi)(qi)，同樣將使(shi)其在一(yi)次過(guo)(guo)電(dian)(dian)(dian)壓(ya)(ya)下吸收 過(guo)(guo)多(duo)而(er)(er)劣化損壞。反(fan)之(zhi)，若(ruo)避(bi)雷(lei)(lei)器(qi)(qi)(qi)額定(ding)電(dian)(dian)(dian)壓(ya)(ya)選(xuan)擇高了，則相(xiang)應的(de)(de)沖擊放(fang)電(dian)(dian)(dian)電(dian)(dian)(dian)壓(ya)(ya)和殘(can)壓(ya)(ya)將 ，保護電(dian)(dian)(dian)氣設備的(de)(de)限壓(ya)(ya)效果(guo)將變(bian)得不好。

　　對(dui)于有間隙的(de)(de)(de)普通(tong)閥式避雷器(qi)(qi)，其閥片的(de)(de)(de)阻(zu)值(zhi)是隨通(tong)過(guo)的(de)(de)(de)電(dian)(dian)(dian)流(liu)而(er)變(bian)化的(de)(de)(de)，當(dang)很(hen)(hen)大雷電(dian)(dian)(dian)流(liu)通(tong)過(guo)閥片時(shi)，其非(fei)線性電(dian)(dian)(dian)阻(zu)呈現很(hen)(hen)大電(dian)(dian)(dian)導率(lv)，使避雷器(qi)(qi)殘壓(ya)不(bu)高(gao)。在正(zheng)常電(dian)(dian)(dian)壓(ya)時(shi)非(fei)線性電(dian)(dian)(dian)阻(zu)的(de)(de)(de)電(dian)(dian)(dian)導率(lv)將下(xia)降，把工頻(pin)續(xu)流(liu)限制到很(hen)(hen)小的(de)(de)(de)數值(zhi)，為(wei)火花間隙切斷續(xu)流(liu)創(chuang)造了良好條件(jian)，使避雷器(qi)(qi)短時(shi)間作用的(de)(de)(de)沖(chong)擊放電(dian)(dian)(dian)電(dian)(dian)(dian)壓(ya)減小，從而(er)保護了變(bian)壓(ya)器(qi)(qi)的(de)(de)(de)a全(quan)運行。

　　在變壓(ya)(ya)器防雷保護中采用了"三(san)位一(yi)(yi)體"的接地方式，其(qi)接地裝置及(ji)接地電阻(zu)值(zhi)能否滿足技術要求，避雷器與變壓(ya)(ya)器之間電氣距離能否實現(xian)"零·距離"，這是變壓(ya)(ya)器能否得保護的關鍵(jian)。因變壓(ya)(ya)器遭(zao)受雷擊時，雷電流經接地電阻(zu)也(ye)會產生電壓(ya)(ya)降，此(ci)電壓(ya)(ya)與殘壓(ya)(ya)疊加(jia)后一(yi)(yi)起(qi)作用在變壓(ya)(ya)器繞組上，同樣也(ye)會威脅到變壓(ya)(ya)器的a全。

　　總之(zhi)，避(bi)(bi)(bi)雷(lei)器(qi)(qi)(qi)的防雷(lei)效(xiao)果，取(qu)決于避(bi)(bi)(bi)雷(lei)器(qi)(qi)(qi)的殘壓(ya)(ya)(ya)、侵入波陡度及(ji)避(bi)(bi)(bi)雷(lei)器(qi)(qi)(qi)與變(bian)壓(ya)(ya)(ya)器(qi)(qi)(qi)之(zhi)間(jian)電(dian)氣距離。在避(bi)(bi)(bi)雷(lei)器(qi)(qi)(qi)的選擇上，須使其(qi)伏秒特(te)性上限低于變(bian)壓(ya)(ya)(ya)器(qi)(qi)(qi)伏秒特(te)性下限，避(bi)(bi)(bi)雷(lei)器(qi)(qi)(qi)殘壓(ya)(ya)(ya)也(ye)應小于變(bian)壓(ya)(ya)(ya)器(qi)(qi)(qi)絕緣耐壓(ya)(ya)(ya)允(yun)許程度，其(qi)數(shu)值也(ye)應小于沖擊波的幅值，這樣(yang)的避(bi)(bi)(bi)雷(lei)器(qi)(qi)(qi)才會有(you)保(bao)護過電(dian)壓(ya)(ya)(ya)的效(xiao)果。

　　4.變(bian)壓器中性(xing)點(dian)過電壓的保護

　　變(bian)(bian)(bian)(bian)電(dian)所處于多(duo)雷(lei)區又是單(dan)電(dian)源進線(xian)，其(qi)三相雷(lei)電(dian)侵入波機率較多(duo)，故(gu)主(zhu)變(bian)(bian)(bian)(bian)壓(ya)器(qi)(qi)(qi)中(zhong)(zhong)(zhong)性(xing)(xing)點(dian)需裝設(she)避雷(lei)器(qi)(qi)(qi)保(bao)(bao)護(hu)。變(bian)(bian)(bian)(bian)壓(ya)器(qi)(qi)(qi)中(zhong)(zhong)(zhong)性(xing)(xing)點(dian)過(guo)電(dian)壓(ya)保(bao)(bao)護(hu)的(de)設(she)置，可(ke)單(dan)獨(du)(du)采(cai)用專門保(bao)(bao)護(hu)變(bian)(bian)(bian)(bian)壓(ya)器(qi)(qi)(qi)中(zhong)(zhong)(zhong)性(xing)(xing)點(dian)的(de)設(she)置，可(ke)單(dan)獨(du)(du)采(cai)用專門保(bao)(bao)護(hu)變(bian)(bian)(bian)(bian)壓(ya)器(qi)(qi)(qi)中(zhong)(zhong)(zhong)性(xing)(xing)點(dian)的(de)無間(jian)隙氧化鋅避雷(lei)器(qi)(qi)(qi)(簡稱中(zhong)(zhong)(zhong)性(xing)(xing)點(dian)MOA)。采(cai)用中(zhong)(zhong)(zhong)性(xing)(xing)點(dian)MOA，可(ke)保(bao)(bao)護(hu)雷(lei)電(dian)過(guo)電(dian)壓(ya)及操作過(guo)電(dian)壓(ya)。其(qi)優點(dian)是：動作靈敏、殘壓(ya)低、通流容量大，對保(bao)(bao)護(hu)主(zhu)變(bian)(bian)(bian)(bian)壓(ya)器(qi)(qi)(qi)中(zhong)(zhong)(zhong)性(xing)(xing)點(dian)免遭過(guo)電(dian)壓(ya)具有良好效(xiao)果。

　　此(ci)(ci)外，現今(jin)的(de)中(zhong)性(xing)點MOA的(de)額(e)定電(dian)(dian)壓(ya)(ya)較高(gao)，當中(zhong)性(xing)點電(dian)(dian)位(wei)偏離不大時(shi)，MOA仍有較好的(de)保護(hu)效果。若接地系(xi)統發生單相接地故障(zhang)時(shi)，主變壓(ya)(ya)器中(zhong)性(xing)點將(jiang)產生一倍的(de)工(gong)頻(pin)相電(dian)(dian)壓(ya)(ya)，此(ci)(ci)電(dian)(dian)壓(ya)(ya)也不會對MOA造成損壞(huai)。

　　若中(zhong)性點(dian)電(dian)位嚴重偏離時，避(bi)(bi)(bi)雷(lei)(lei)器(qi)運行中(zhong)自身a全(quan)將受到威脅，當(dang)中(zhong)性點(dian)過電(dian)壓(ya)(ya)達(da)到工頻相電(dian)壓(ya)(ya)的(de)2倍(bei)以(yi)上(shang)(shang)時，此(ci)時避(bi)(bi)(bi)雷(lei)(lei)器(qi)會因通流(liu)量不夠而(er)損(sun)壞，并可(ke)能危及主變的(de)a全(quan)。盡管這種情況發(fa)生的(de)概率很少，但(dan)為(wei)(wei)了(le)主變的(de)a全(quan)，除采用(yong)中(zhong)性點(dian)MOA保護(hu)(hu)主變中(zhong)性點(dian)過電(dian)壓(ya)(ya)外，還可(ke)在(zai)避(bi)(bi)(bi)雷(lei)(lei)器(qi)邊上(shang)(shang)并聯(lian)水平棒間(jian)隙(xi)來限(xian)制(zhi)工頻過電(dian)壓(ya)(ya)。棒間(jian)隙(xi)并聯(lian)避(bi)(bi)(bi)雷(lei)(lei)器(qi)的(de)保護(hu)(hu)作用(yong)是：雷(lei)(lei)電(dian)、操作過電(dian)壓(ya)(ya)由(you)避(bi)(bi)(bi)雷(lei)(lei)器(qi)承擔保護(hu)(hu)，而(er)間(jian)隙(xi)則是用(yong)來限(xian)制(zhi)避(bi)(bi)(bi)雷(lei)(lei)器(qi)上(shang)(shang)出現的(de)幅值較(jiao)高的(de)工頻過電(dian)壓(ya)(ya)。這種保護(hu)(hu)的(de)設置方式，既對變壓(ya)(ya)器(qi)中(zhong)性點(dian)過電(dian)壓(ya)(ya)進(jin)行保護(hu)(hu)，又達(da)到了(le)互為(wei)(wei)保護(hu)(hu)的(de)目的(de)。

　　5.三繞組變壓(ya)器的保護

　　三(san)繞(rao)(rao)(rao)組(zu)(zu)變(bian)壓(ya)(ya)(ya)(ya)(ya)器(qi)具有高、中、低(di)(di)壓(ya)(ya)(ya)(ya)(ya)三(san)個繞(rao)(rao)(rao)組(zu)(zu)，其運(yun)行(xing)中若(ruo)遭雷(lei)擊(ji)高壓(ya)(ya)(ya)(ya)(ya)側有雷(lei)電(dian)波(bo)侵(qin)入(ru)時(shi)，會通過(guo)(guo)靜電(dian)耦合和電(dian)磁感應向低(di)(di)壓(ya)(ya)(ya)(ya)(ya)繞(rao)(rao)(rao)組(zu)(zu)傳遞(di)過(guo)(guo)電(dian)壓(ya)(ya)(ya)(ya)(ya)。在(zai)高、中壓(ya)(ya)(ya)(ya)(ya)繞(rao)(rao)(rao)組(zu)(zu)運(yun)行(xing)，低(di)(di)壓(ya)(ya)(ya)(ya)(ya)繞(rao)(rao)(rao)組(zu)(zu)開路(lu)時(shi)，低(di)(di)壓(ya)(ya)(ya)(ya)(ya)繞(rao)(rao)(rao)組(zu)(zu)對地電(dian)容值較(jiao)小，其繞(rao)(rao)(rao)組(zu)(zu)上的靜電(dian)感應電(dian)壓(ya)(ya)(ya)(ya)(ya)分(fen)量可達到(dao)較(jiao)高值，因而(er)會危(wei)(wei)及(ji)低(di)(di)壓(ya)(ya)(ya)(ya)(ya)繞(rao)(rao)(rao)組(zu)(zu)的絕(jue)緣a全，為限制過(guo)(guo)電(dian)壓(ya)(ya)(ya)(ya)(ya)的危(wei)(wei)害，低(di)(di)壓(ya)(ya)(ya)(ya)(ya)繞(rao)(rao)(rao)組(zu)(zu)則需在(zai)出口外裝設避雷(lei)器(qi)進行(xing)保護。

　　變(bian)壓(ya)(ya)(ya)器(qi)運(yun)行中，若(ruo)系(xi)統發生不對稱接(jie)(jie)地(di)故障，或(huo)斷路(lu)器(qi)的非全相動(dong)作(zuo)等而出現零序電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)時，此電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)將通過電(dian)(dian)(dian)(dian)容耦合傳遞(di)到低(di)壓(ya)(ya)(ya)繞(rao)組。由(you)于這種電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)具(ju)有工頻過電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)特性(xing)，同(tong)樣也會危及低(di)壓(ya)(ya)(ya)繞(rao)組絕緣的a全。為此，除選用同(tong)期(qi)性(xing)能好(hao)的斷路(lu)器(qi)外，通常在變(bian)壓(ya)(ya)(ya)器(qi)低(di)壓(ya)(ya)(ya)側(ce)母線(xian)橋上(shang)加裝3只Y。接(jie)(jie)線(xian)的電(dian)(dian)(dian)(dian)容器(qi)，用以增加低(di)壓(ya)(ya)(ya)側(ce)對地(di)電(dian)(dian)(dian)(dian)容，能吸收和降低(di)過電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)幅值和陡度，從而起到保護過電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)的效果(guo)。

　　6.變壓器低壓系統的保護

　　變壓(ya)(ya)(ya)(ya)(ya)器(qi)低(di)(di)(di)壓(ya)(ya)(ya)(ya)(ya)側(ce)供電(dian)線路較長，容(rong)易遭(zao)受雷(lei)電(dian)波的侵襲，當低(di)(di)(di)壓(ya)(ya)(ya)(ya)(ya)線路遭(zao)受雷(lei)擊時，電(dian)壓(ya)(ya)(ya)(ya)(ya)分別在低(di)(di)(di)壓(ya)(ya)(ya)(ya)(ya)繞組和接地(di)電(dian)阻(zu)上(shang)，侵入的雷(lei)電(dian)流由于(yu)電(dian)磁(ci)感應(ying)(ying)會按變壓(ya)(ya)(ya)(ya)(ya)器(qi)的變比在高(gao)(gao)壓(ya)(ya)(ya)(ya)(ya)繞組上(shang)產生感應(ying)(ying)過電(dian)壓(ya)(ya)(ya)(ya)(ya)。為避免逆變換過電(dian)壓(ya)(ya)(ya)(ya)(ya)對高(gao)(gao)壓(ya)(ya)(ya)(ya)(ya)繞組造成危害，其低(di)(di)(di)壓(ya)(ya)(ya)(ya)(ya)側(ce)出口也需裝設一組金(jin)屬氧化物(wu)避雷(lei)器(qi)，用以低(di)(di)(di)壓(ya)(ya)(ya)(ya)(ya)繞組產生的沖擊磁(ci)通，從而起到過電(dian)壓(ya)(ya)(ya)(ya)(ya)的保護(hu)作用。

　　此外(wai)，由(you)于Y、Zn11聯結(jie)組變(bian)(bian)壓(ya)(ya)器繞組結(jie)構上(shang)的(de)特點，若采用這種變(bian)(bian)壓(ya)(ya)器對逆變(bian)(bian)換過電氣(qi)也(ye)有很好作(zuo)用，能保護(hu)"逆變(bian)(bian)換過電壓(ya)(ya)"對變(bian)(bian)壓(ya)(ya)器的(de)損壞。

　　變壓(ya)器(qi)是電(dian)(dian)力系統重(zhong)要設(she)(she)備，其絕緣水平相對(dui)比較薄(bo)弱，而過(guo)電(dian)(dian)壓(ya)造成變壓(ya)器(qi)損壞的(de)(de)概率Z大(da)。為確(que)保(bao)變壓(ya)器(qi)a全可靠運(yun)行(xing)(xing)，除選用變壓(ya)器(qi)外，仍需(xu)對(dui)運(yun)行(xing)(xing)的(de)(de)變壓(ya)器(qi)設(she)(she)置(zhi)過(guo)電(dian)(dian)壓(ya)保(bao)護(hu)。根據電(dian)(dian)網(wang)(wang)運(yun)行(xing)(xing)特點(dian)(dian)和接地(di)方式，變壓(ya)器(qi)中(zhong)(zhong)性點(dian)(dian)出現過(guo)電(dian)(dian)壓(ya)機率也較多(duo)，除在變電(dian)(dian)所、電(dian)(dian)網(wang)(wang)進行(xing)(xing)過(guo)電(dian)(dian)壓(ya)保(bao)護(hu)外，還(huan)要在變壓(ya)器(qi)中(zhong)(zhong)性點(dian)(dian)設(she)(she)置(zhi)合理的(de)(de)過(guo)電(dian)(dian)壓(ya)保(bao)護(hu)，確(que)保(bao)變壓(ya)器(qi)a全穩定(ding)運(yun)行(xing)(xing)。