試驗(yan)變(bian)壓(ya)(ya)(ya)器和(he)電(dian)(dian)(dian)(dian)力變(bian)壓(ya)(ya)(ya)器是利用電(dian)(dian)(dian)(dian)磁感(gan)應原理，將(jiang)一(yi)個(ge)等(deng)(deng)級(ji)的(de)交(jiao)流電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)和(he)電(dian)(dian)(dian)(dian)流變(bian)成(cheng)(cheng)頻率(lv)相同的(de)另一(yi)個(ge)等(deng)(deng)級(ji)或(huo)幾種不(bu)同等(deng)(deng)級(ji)的(de)電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)和(he)電(dian)(dian)(dian)(dian)流的(de)電(dian)(dian)(dian)(dian)器。試驗(yan)變(bian)壓(ya)(ya)(ya)器屬(shu)于升壓(ya)(ya)(ya)變(bian)壓(ya)(ya)(ya)器，電(dian)(dian)(dian)(dian)力變(bian)壓(ya)(ya)(ya)器屬(shu)于降壓(ya)(ya)(ya)變(bian)壓(ya)(ya)(ya)器具多，其作用是將(jiang)不(bu)同電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)等(deng)(deng)級(ji)的(de)輸電(dian)(dian)(dian)(dian)線路和(he)設備連接成(cheng)(cheng)為一(yi)個(ge)整體。電(dian)(dian)(dian)(dian)力變(bian)壓(ya)(ya)(ya)器由1個(ge)或(huo)幾個(ge)繞(rao)組套于鐵心上制成(cheng)(cheng)。不(bu)同繞(rao)組間通過磁鏈的(de)耦合，使電(dian)(dian)(dian)(dian)能得以在不(bu)同的(de)電(dian)(dian)(dian)(dian)回路中傳遞，以實現傳輸和(he)分(fen)配電(dian)(dian)(dian)(dian)能的(de)目的(de)。

　　特(te)(te)、超(chao)高(gao)(gao)壓(ya)(ya)(ya)(ya)(ya)電(dian)(dian)力變(bian)(bian)(bian)(bian)壓(ya)(ya)(ya)(ya)(ya)器(qi)(qi)的(de)繞組一般(ban)都是糾(jiu)結(jie)式。特(te)(te)、超(chao)高(gao)(gao)壓(ya)(ya)(ya)(ya)(ya)電(dian)(dian)力變(bian)(bian)(bian)(bian)壓(ya)(ya)(ya)(ya)(ya)器(qi)(qi)按用途不同可分(fen)為升壓(ya)(ya)(ya)(ya)(ya)變(bian)(bian)(bian)(bian)壓(ya)(ya)(ya)(ya)(ya)器(qi)(qi)、降壓(ya)(ya)(ya)(ya)(ya)變(bian)(bian)(bian)(bian)壓(ya)(ya)(ya)(ya)(ya)器(qi)(qi)、聯絡(luo)變(bian)(bian)(bian)(bian)壓(ya)(ya)(ya)(ya)(ya)器(qi)(qi)等。特(te)(te)高(gao)(gao)壓(ya)(ya)(ya)(ya)(ya)電(dian)(dian)力變(bian)(bian)(bian)(bian)壓(ya)(ya)(ya)(ya)(ya)器(qi)(qi)主要(yao)有(you)發電(dian)(dian)機(ji)升壓(ya)(ya)(ya)(ya)(ya)變(bian)(bian)(bian)(bian)壓(ya)(ya)(ya)(ya)(ya)器(qi)(qi)（兩繞組）和自耦變(bian)(bian)(bian)(bian)壓(ya)(ya)(ya)(ya)(ya)器(qi)(qi)2類。由于特(te)(te)高(gao)(gao)壓(ya)(ya)(ya)(ya)(ya)輸電(dian)(dian)系統的(de)中性(xing)(xing)點都是直(zhi)接(jie)接(jie)地(di)，自耦變(bian)(bian)(bian)(bian)壓(ya)(ya)(ya)(ya)(ya)器(qi)(qi)的(de)中性(xing)(xing)點一般(ban)也是直(zhi)接(jie)接(jie)地(di)，其絕緣(yuan)水(shui)平很(hen)低。自耦變(bian)(bian)(bian)(bian)壓(ya)(ya)(ya)(ya)(ya)器(qi)(qi)如果需(xu)要(yao)有(you)載(zai)調壓(ya)(ya)(ya)(ya)(ya)，一般(ban)都在中性(xing)(xing)點調壓(ya)(ya)(ya)(ya)(ya)。發電(dian)(dian)機(ji)升壓(ya)(ya)(ya)(ya)(ya)變(bian)(bian)(bian)(bian)壓(ya)(ya)(ya)(ya)(ya)器(qi)(qi)不需(xu)要(yao)有(you)載(zai)調壓(ya)(ya)(ya)(ya)(ya)裝(zhuang)置，甚至不設無載(zai)調壓(ya)(ya)(ya)(ya)(ya)分(fen)接(jie)頭，以簡化特(te)(te)高(gao)(gao)壓(ya)(ya)(ya)(ya)(ya)大型變(bian)(bian)(bian)(bian)壓(ya)(ya)(ya)(ya)(ya)器(qi)(qi)的(de)結(jie)構。

　　特高(gao)壓電力(li)變壓器的(de)特點如下：（1）容(rong)量(liang)(liang)很大，一般(ban)三相(xiang)(xiang)容(rong)量(liang)(liang)都在(zai)1000MVA以(yi)上，甚至達到幾千兆伏安；（2）絕緣水(shui)平(ping)高(gao)，基準絕緣水(shui)平(ping)（雷電沖(chong)擊絕緣水(shui)平(ping)）高(gao)，一般(ban)在(zai)1950～2250kV之間或更高(gao)；（3）由于容(rong)量(liang)(liang)大和絕緣水(shui)平(ping)高(gao)，其(qi)重量(liang)(liang)與體積(ji)必(bi)然很大；（4）設(she)計(ji)和制造時需要考慮運輸的(de)條件，一般(ban)為單相(xiang)(xiang)結構。

　　在(zai)特、超高壓變電(dian)設備中，變壓器是最昂貴的(de)(de)設備，考慮到它在(zai)系(xi)統(tong)中所占(zhan)的(de)(de)重要地(di)位，對其(qi)可(ke)靠(kao)性提出很高的(de)(de)要求。因此(ci)，都采用在(zai)靠(kao)近變壓器的(de)(de)位置安裝避雷器保護(hu)，變壓器的(de)(de)操作和雷電(dian)沖擊試驗電(dian)壓的(de)(de)取(qu)值(zhi)一般(ban)比開(kai)關類設備低。