為防止雷電波入侵干式變壓器，確保干式變壓器安全運行，本文介紹了干式變壓器防雷保護措施的應用，可以改善雷電 - 干式變壓器的防水等級。

　　干式變壓器(qi)

　　(1)在(zai)(zai)配(pei)電變壓(ya)(ya)器的(de)(de)高壓(ya)(ya)側(ce)(ce)安裝避(bi)雷(lei)器。根據(ju)SDJ7-79“電力設備(bei)過電壓(ya)(ya)保護技術規定(ding)”：“配(pei)電變壓(ya)(ya)器的(de)(de)高壓(ya)(ya)側(ce)(ce)一般應(ying)采用避(bi)雷(lei)器保護。避(bi)雷(lei)器的(de)(de)接(jie)地線和(he)低(di)壓(ya)(ya)中(zhong)性點變壓(ya)(ya)器的(de)(de)電壓(ya)(ya)側(ce)(ce)和(he)變壓(ya)(ya)器的(de)(de)金屬外殼應(ying)連接(jie)在(zai)(zai)一起(qi)。“這也是(shi)外交(jiao)部(bu)推薦的(de)(de)防雷(lei)措施DL / T620-1997”交(jiao)流電氣裝置(zhi)的(de)(de)過電壓(ya)(ya)保護和(he)絕(jue)緣配(pei)合(he)”。

　　然而，大量(liang)的研(yan)究(jiu)和(he)操(cao)作經驗表明(ming)，僅當避雷(lei)(lei)器(qi)用(yong)于(yu)高(gao)壓(ya)側時，仍(reng)然會受到雷(lei)(lei)電(dian)波的損(sun)壞。在(zai)一般地區(qu)，年損(sun)害率為1%，在(zai)多礦區(qu)，可(ke)達(da)到5%。在(zai)一些雷(lei)(lei)暴強(qiang)度為100雷(lei)(lei)暴天的地區(qu)，年損(sun)害率高(gao)達(da)50%。主要原(yuan)因是雷(lei)(lei)電(dian)波侵入了配(pei)電(dian)變壓(ya)器(qi)高(gao)壓(ya)側繞組引起的正(zheng)負轉換(huan)過電(dian)壓(ya)。正(zheng)負轉換(huan)過壓(ya)產生的機制如下(xia)：

　　1逆變換過(guo)電(dian)(dian)壓(ya)(ya)(ya)。也就(jiu)是說，當3到(dao)10kV時(shi)當側(ce)面(mian)侵(qin)入雷(lei)(lei)電(dian)(dian)波并使避(bi)(bi)雷(lei)(lei)器(qi)工作時(shi)，大量(liang)的(de)(de)(de)(de)浪(lang)涌(yong)電(dian)(dian)流(liu)流(liu)過(guo)接地電(dian)(dian)阻以(yi)產(chan)生電(dian)(dian)壓(ya)(ya)(ya)降。該(gai)電(dian)(dian)壓(ya)(ya)(ya)降作用(yong)于(yu)低(di)(di)(di)(di)壓(ya)(ya)(ya)繞(rao)(rao)組(zu)(zu)(zu)的(de)(de)(de)(de)中(zhong)性點(dian)(dian)，使得中(zhong)性點(dian)(dian)電(dian)(dian)位(wei)(wei)上升，而(er)當低(di)(di)(di)(di)壓(ya)(ya)(ya)線相對較長時(shi)，低(di)(di)(di)(di)壓(ya)(ya)(ya)線相當于(yu)波阻抗(kang)接地。因此(ci)，在(zai)(zai)中(zhong)性點(dian)(dian)電(dian)(dian)位(wei)(wei)的(de)(de)(de)(de)作用(yong)下(xia)，低(di)(di)(di)(di)壓(ya)(ya)(ya)繞(rao)(rao)組(zu)(zu)(zu)流(liu)過(guo)大的(de)(de)(de)(de)浪(lang)涌(yong)電(dian)(dian)流(liu)，在(zai)(zai)三(san)相繞(rao)(rao)組(zu)(zu)(zu)中(zhong)流(liu)動的(de)(de)(de)(de)浪(lang)涌(yong)電(dian)(dian)流(liu)具有相同(tong)的(de)(de)(de)(de)方向和(he)相同(tong)的(de)(de)(de)(de)大小，由它們產(chan)生的(de)(de)(de)(de)磁通(tong)(tong)量(liang)是根(gen)據變壓(ya)(ya)(ya)器(qi)匝數比在(zai)(zai)高(gao)壓(ya)(ya)(ya)繞(rao)(rao)組(zu)(zu)(zu)中(zhong)感應(ying)出(chu)。脈沖電(dian)(dian)位(wei)(wei)非常高(gao)。三(san)相脈沖電(dian)(dian)位(wei)(wei)具有相同(tong)的(de)(de)(de)(de)方向和(he)相同(tong)的(de)(de)(de)(de)尺寸。由于(yu)高(gao)壓(ya)(ya)(ya)繞(rao)(rao)組(zu)(zu)(zu)以(yi)星(xing)形連接而(er)中(zhong)性點(dian)(dian)未接地，所(suo)以(yi)在(zai)(zai)高(gao)壓(ya)(ya)(ya)繞(rao)(rao)組(zu)(zu)(zu)中(zhong)，盡管存(cun)在(zai)(zai)脈沖電(dian)(dian)位(wei)(wei)，但(dan)沒(mei)有浪(lang)涌(yong)電(dian)(dian)流(liu)。浪(lang)涌(yong)電(dian)(dian)流(liu)僅在(zai)(zai)低(di)(di)(di)(di)壓(ya)(ya)(ya)繞(rao)(rao)組(zu)(zu)(zu)中(zhong)流(liu)動，并且(qie)高(gao)壓(ya)(ya)(ya)繞(rao)(rao)組(zu)(zu)(zu)中(zhong)沒(mei)有相應(ying)的(de)(de)(de)(de)浪(lang)涌(yong)電(dian)(dian)流(liu)來平衡。因此(ci)，低(di)(di)(di)(di)壓(ya)(ya)(ya)繞(rao)(rao)組(zu)(zu)(zu)中(zhong)的(de)(de)(de)(de)浪(lang)涌(yong)電(dian)(dian)流(liu)全(quan)部變為勵磁電(dian)(dian)流(liu)，產(chan)生大的(de)(de)(de)(de)零序(xu)磁通(tong)(tong)，從而(er)高(gao)壓(ya)(ya)(ya)側(ce)產(chan)生高(gao)電(dian)(dian)位(wei)(wei)。由于(yu)高(gao)壓(ya)(ya)(ya)繞(rao)(rao)組(zu)(zu)(zu)輸出(chu)端的(de)(de)(de)(de)電(dian)(dian)位(wei)(wei)由避(bi)(bi)雷(lei)(lei)器(qi)的(de)(de)(de)(de)剩余電(dian)(dian)壓(ya)(ya)(ya)決定，因此(ci)該(gai)感應(ying)電(dian)(dian)位(wei)(wei)沿繞(rao)(rao)組(zu)(zu)(zu)分布，振(zhen)幅(fu)在(zai)(zai)中(zhong)性點(dian)(dian)處(chu)較大。因此(ci)，中(zhong)性點(dian)(dian)絕緣容易破壞。同(tong)時(shi)，層(ceng)和(he)匝之間(jian)的(de)(de)(de)(de)電(dian)(dian)位(wei)(wei)梯(ti)度相應(ying)地增(zeng)加，并且(qie)在(zai)(zai)其他位(wei)(wei)置處(chu)可能發生層(ceng)間(jian)和(he)匝間(jian)絕緣擊(ji)穿。這(zhe)種過(guo)電(dian)(dian)壓(ya)(ya)(ya)先先是由高(gao)壓(ya)(ya)(ya)電(dian)(dian)波引起(qi)的(de)(de)(de)(de)，然后是通(tong)(tong)過(guo)低(di)(di)(di)(di)壓(ya)(ya)(ya)電(dian)(dian)磁感應(ying)到(dao)高(gao)壓(ya)(ya)(ya)繞(rao)(rao)組(zu)(zu)(zu)，通(tong)(tong)常稱(cheng)為逆變換。

　　2正(zheng)(zheng)轉換(huan)過壓(ya)(ya)。所謂的(de)(de)正(zheng)(zheng)過電(dian)(dian)(dian)壓(ya)(ya)，即當雷電(dian)(dian)(dian)波被低壓(ya)(ya)線侵入(ru)時(shi)，配(pei)電(dian)(dian)(dian)變(bian)壓(ya)(ya)器的(de)(de)低壓(ya)(ya)繞組(zu)(zu)有一個浪涌(yong)(yong)電(dian)(dian)(dian)流，浪涌(yong)(yong)電(dian)(dian)(dian)流也會產生感(gan)應(ying)電(dian)(dian)(dian)動勢。根據匝(za)數比的(de)(de)高壓(ya)(ya)繞組(zu)(zu)，使(shi)得高壓(ya)(ya)側中性點電(dian)(dian)(dian)位It大大提高，并(bing)且層和(he)匝(za)之(zhi)間的(de)(de)梯(ti)度電(dian)(dian)(dian)壓(ya)(ya)也相應(ying)地增加(jia)。由于低電(dian)(dian)(dian)壓(ya)(ya)入(ru)射(she)波而在高壓(ya)(ya)側產生感(gan)應(ying)過電(dian)(dian)(dian)壓(ya)(ya)的(de)(de)過程稱為(wei)正(zheng)(zheng)向變(bian)換(huan)。試(shi)驗(yan)表明，當低壓(ya)(ya)輸入(ru)波為(wei)10kV，接地電(dian)(dian)(dian)阻為(wei)5Ω時(shi)，高壓(ya)(ya)繞組(zu)(zu)上的(de)(de)層間梯(ti)度電(dian)(dian)(dian)壓(ya)(ya)超(chao)過配(pei)電(dian)(dian)(dian)變(bian)壓(ya)(ya)器的(de)(de)層間絕(jue)(jue)緣(yuan)全波沖擊強度一倍以上。在這種情況下，變(bian)壓(ya)(ya)器層間絕(jue)(jue)緣(yuan)絕(jue)(jue)對要(yao)穿透。

　　(2)在(zai)配電變(bian)(bian)壓器的(de)低壓側(ce)安裝普通閥(fa)式(shi)(shi)避雷(lei)(lei)器或金(jin)屬(shu)(shu)氧化物(wu)避雷(lei)(lei)器。這(zhe)種保護方式(shi)(shi)的(de)接線是：變(bian)(bian)壓器高低避雷(lei)(lei)器的(de)接地(di)線，低壓側(ce)的(de)中(zhong)性點和(he)變(bian)(bian)壓器的(de)金(jin)屬(shu)(shu)外殼在(zai)四個點(或三(san)個點)連接到(dao)地(di)面(mian)。

　　運行經驗和實驗研(yan)究表明，對于具有(you)良好(hao)絕(jue)緣性的(de)(de)配電(dian)變(bian)(bian)(bian)壓器(qi)(qi)，當避雷(lei)器(qi)(qi)安(an)裝(zhuang)在(zai)高壓側(ce)(ce)時，仍會出現由正負(fu)過電(dian)壓引起的(de)(de)雷(lei)電(dian)事(shi)故。這是(shi)因(yin)為安(an)裝(zhuang)在(zai)高壓側(ce)(ce)的(de)(de)避雷(lei)器(qi)(qi)對于正或負(fu)轉換過電(dian)壓是(shi)無能為力的(de)(de)。在(zai)正向(xiang)和反(fan)向(xiang)變(bian)(bian)(bian)換的(de)(de)作(zuo)用下的(de)(de)層間梯度與(yu)變(bian)(bian)(bian)壓器(qi)(qi)的(de)(de)匝數成比例。它與(yu)繞組(zu)的(de)(de)分(fen)布有(you)關。繞組(zu)的(de)(de)較好(hao)端，中間和末(mo)端可(ke)能會損壞，但較終(zhong)會更危險。安(an)裝(zhuang)在(zai)低壓側(ce)(ce)的(de)(de)避雷(lei)器(qi)(qi)可(ke)以將(jiang)正向(xiang)和反(fan)向(xiang)轉換過電(dian)壓限(xian)制在(zai)一(yi)定(ding)范圍(wei)內。

　　(3)高壓(ya)(ya)側(ce)和低壓(ya)(ya)側(ce)接(jie)地(di)的保護方(fang)法。該保護方(fang)式的接(jie)線(xian)是高壓(ya)(ya)側(ce)避雷器分別接(jie)地(di)，低壓(ya)(ya)側(ce)未配備避雷器，低壓(ya)(ya)側(ce)中性點和變壓(ya)(ya)器金屬外(wai)殼連(lian)接(jie)在(zai)一起，并分別接(jie)地(di)從(cong)高壓(ya)(ya)側(ce)接(jie)地(di)。