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)在配電(dian)變(bian)壓(ya)器(qi)的(de)(de)(de)高壓(ya)側(ce)安裝避雷(lei)器(qi)。根據SDJ7-79“電(dian)力設備過(guo)電(dian)壓(ya)保護(hu)技術規(gui)定”：“配電(dian)變(bian)壓(ya)器(qi)的(de)(de)(de)高壓(ya)側(ce)一般應(ying)采用避雷(lei)器(qi)保護(hu)。避雷(lei)器(qi)的(de)(de)(de)接地(di)線和(he)低壓(ya)中性點變(bian)壓(ya)器(qi)的(de)(de)(de)電(dian)壓(ya)側(ce)和(he)變(bian)壓(ya)器(qi)的(de)(de)(de)金屬外(wai)殼應(ying)連接在一起。“這也是外(wai)交(jiao)部(bu)推薦的(de)(de)(de)防雷(lei)措施DL / T620-1997”交(jiao)流(liu)電(dian)氣(qi)裝置的(de)(de)(de)過(guo)電(dian)壓(ya)保護(hu)和(he)絕緣配合”。

　　然而，大(da)量(liang)的(de)研究和(he)操作經驗表明，僅(jin)當避雷(lei)器用于高壓側時，仍(reng)然會(hui)受到(dao)雷(lei)電(dian)(dian)波(bo)的(de)損(sun)壞。在(zai)(zai)一(yi)般地區(qu)，年(nian)損(sun)害率(lv)為1%，在(zai)(zai)多(duo)礦區(qu)，可達(da)(da)到(dao)5%。在(zai)(zai)一(yi)些(xie)雷(lei)暴(bao)強度為100雷(lei)暴(bao)天的(de)地區(qu)，年(nian)損(sun)害率(lv)高達(da)(da)50%。主要原因(yin)是(shi)雷(lei)電(dian)(dian)波(bo)侵(qin)入了配電(dian)(dian)變壓器高壓側繞(rao)組引起的(de)正(zheng)負(fu)轉換(huan)過電(dian)(dian)壓。正(zheng)負(fu)轉換(huan)過壓產生的(de)機(ji)制(zhi)如下：

　　1逆(ni)變(bian)換(huan)過電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)。也就是說(shuo)，當3到10kV時當側面侵入(ru)雷(lei)電(dian)(dian)(dian)(dian)波(bo)并(bing)使避(bi)雷(lei)器工(gong)作時，大量的(de)(de)(de)(de)浪(lang)(lang)涌(yong)(yong)電(dian)(dian)(dian)(dian)流(liu)流(liu)過接(jie)(jie)地(di)(di)電(dian)(dian)(dian)(dian)阻以(yi)產生(sheng)(sheng)(sheng)電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)降。該電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)降作用于(yu)(yu)低(di)壓(ya)(ya)(ya)繞(rao)組(zu)(zu)的(de)(de)(de)(de)中(zhong)(zhong)(zhong)(zhong)(zhong)(zhong)性(xing)(xing)點(dian)(dian)(dian)，使得中(zhong)(zhong)(zhong)(zhong)(zhong)(zhong)性(xing)(xing)點(dian)(dian)(dian)電(dian)(dian)(dian)(dian)位(wei)(wei)(wei)上升(sheng)，而當低(di)壓(ya)(ya)(ya)線(xian)相(xiang)對較長(chang)時，低(di)壓(ya)(ya)(ya)線(xian)相(xiang)當于(yu)(yu)波(bo)阻抗接(jie)(jie)地(di)(di)。因此，在(zai)中(zhong)(zhong)(zhong)(zhong)(zhong)(zhong)性(xing)(xing)點(dian)(dian)(dian)電(dian)(dian)(dian)(dian)位(wei)(wei)(wei)的(de)(de)(de)(de)作用下，低(di)壓(ya)(ya)(ya)繞(rao)組(zu)(zu)流(liu)過大的(de)(de)(de)(de)浪(lang)(lang)涌(yong)(yong)電(dian)(dian)(dian)(dian)流(liu)，在(zai)三相(xiang)繞(rao)組(zu)(zu)中(zhong)(zhong)(zhong)(zhong)(zhong)(zhong)流(liu)動的(de)(de)(de)(de)浪(lang)(lang)涌(yong)(yong)電(dian)(dian)(dian)(dian)流(liu)具(ju)有相(xiang)同(tong)(tong)的(de)(de)(de)(de)方向和相(xiang)同(tong)(tong)的(de)(de)(de)(de)大小，由它們(men)產生(sheng)(sheng)(sheng)的(de)(de)(de)(de)磁(ci)通量是根據變(bian)壓(ya)(ya)(ya)器匝數比在(zai)高(gao)壓(ya)(ya)(ya)繞(rao)組(zu)(zu)中(zhong)(zhong)(zhong)(zhong)(zhong)(zhong)感(gan)應(ying)(ying)(ying)出(chu)。脈沖(chong)電(dian)(dian)(dian)(dian)位(wei)(wei)(wei)非常(chang)高(gao)。三相(xiang)脈沖(chong)電(dian)(dian)(dian)(dian)位(wei)(wei)(wei)具(ju)有相(xiang)同(tong)(tong)的(de)(de)(de)(de)方向和相(xiang)同(tong)(tong)的(de)(de)(de)(de)尺寸。由于(yu)(yu)高(gao)壓(ya)(ya)(ya)繞(rao)組(zu)(zu)以(yi)星形連(lian)接(jie)(jie)而中(zhong)(zhong)(zhong)(zhong)(zhong)(zhong)性(xing)(xing)點(dian)(dian)(dian)未(wei)接(jie)(jie)地(di)(di)，所以(yi)在(zai)高(gao)壓(ya)(ya)(ya)繞(rao)組(zu)(zu)中(zhong)(zhong)(zhong)(zhong)(zhong)(zhong)，盡管存(cun)在(zai)脈沖(chong)電(dian)(dian)(dian)(dian)位(wei)(wei)(wei)，但沒有浪(lang)(lang)涌(yong)(yong)電(dian)(dian)(dian)(dian)流(liu)。浪(lang)(lang)涌(yong)(yong)電(dian)(dian)(dian)(dian)流(liu)僅在(zai)低(di)壓(ya)(ya)(ya)繞(rao)組(zu)(zu)中(zhong)(zhong)(zhong)(zhong)(zhong)(zhong)流(liu)動，并(bing)且高(gao)壓(ya)(ya)(ya)繞(rao)組(zu)(zu)中(zhong)(zhong)(zhong)(zhong)(zhong)(zhong)沒有相(xiang)應(ying)(ying)(ying)的(de)(de)(de)(de)浪(lang)(lang)涌(yong)(yong)電(dian)(dian)(dian)(dian)流(liu)來平衡。因此，低(di)壓(ya)(ya)(ya)繞(rao)組(zu)(zu)中(zhong)(zhong)(zhong)(zhong)(zhong)(zhong)的(de)(de)(de)(de)浪(lang)(lang)涌(yong)(yong)電(dian)(dian)(dian)(dian)流(liu)全部變(bian)為勵磁(ci)電(dian)(dian)(dian)(dian)流(liu)，產生(sheng)(sheng)(sheng)大的(de)(de)(de)(de)零序磁(ci)通，從(cong)而高(gao)壓(ya)(ya)(ya)側產生(sheng)(sheng)(sheng)高(gao)電(dian)(dian)(dian)(dian)位(wei)(wei)(wei)。由于(yu)(yu)高(gao)壓(ya)(ya)(ya)繞(rao)組(zu)(zu)輸出(chu)端的(de)(de)(de)(de)電(dian)(dian)(dian)(dian)位(wei)(wei)(wei)由避(bi)雷(lei)器的(de)(de)(de)(de)剩余電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)決定，因此該感(gan)應(ying)(ying)(ying)電(dian)(dian)(dian)(dian)位(wei)(wei)(wei)沿(yan)繞(rao)組(zu)(zu)分布，振幅在(zai)中(zhong)(zhong)(zhong)(zhong)(zhong)(zhong)性(xing)(xing)點(dian)(dian)(dian)處較大。因此，中(zhong)(zhong)(zhong)(zhong)(zhong)(zhong)性(xing)(xing)點(dian)(dian)(dian)絕緣容易破壞(huai)。同(tong)(tong)時，層(ceng)和匝之(zhi)間(jian)的(de)(de)(de)(de)電(dian)(dian)(dian)(dian)位(wei)(wei)(wei)梯度相(xiang)應(ying)(ying)(ying)地(di)(di)增加，并(bing)且在(zai)其(qi)他位(wei)(wei)(wei)置處可能發生(sheng)(sheng)(sheng)層(ceng)間(jian)和匝間(jian)絕緣擊(ji)穿。這種過電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)先先是由高(gao)壓(ya)(ya)(ya)電(dian)(dian)(dian)(dian)波(bo)引起的(de)(de)(de)(de)，然后是通過低(di)壓(ya)(ya)(ya)電(dian)(dian)(dian)(dian)磁(ci)感(gan)應(ying)(ying)(ying)到高(gao)壓(ya)(ya)(ya)繞(rao)組(zu)(zu)，通常(chang)稱為逆(ni)變(bian)換(huan)。

　　2正轉(zhuan)換過(guo)壓。所謂的(de)正過(guo)電壓，即當雷電波(bo)(bo)被(bei)低(di)壓線侵入時，配電變(bian)壓器(qi)的(de)低(di)壓繞組有(you)一個浪涌電流(liu)，浪涌電流(liu)也(ye)會產生感應(ying)電動勢。根據匝數比的(de)高(gao)壓繞組，使得高(gao)壓側(ce)(ce)中性點(dian)電位(wei)It大大提高(gao)，并(bing)且層(ceng)(ceng)和匝之間(jian)(jian)的(de)梯度電壓也(ye)相應(ying)地增(zeng)加。由(you)于低(di)電壓入射波(bo)(bo)而在高(gao)壓側(ce)(ce)產生感應(ying)過(guo)電壓的(de)過(guo)程(cheng)稱為正向變(bian)換。試驗(yan)表明，當低(di)壓輸入波(bo)(bo)為10kV，接地電阻(zu)為5Ω時，高(gao)壓繞組上的(de)層(ceng)(ceng)間(jian)(jian)梯度電壓超(chao)過(guo)配電變(bian)壓器(qi)的(de)層(ceng)(ceng)間(jian)(jian)絕(jue)緣(yuan)全波(bo)(bo)沖擊強度一倍以(yi)上。在這種(zhong)情(qing)況下，變(bian)壓器(qi)層(ceng)(ceng)間(jian)(jian)絕(jue)緣(yuan)絕(jue)對要穿透。

　　(2)在配(pei)電變(bian)壓器(qi)的(de)低(di)壓側安(an)裝普通(tong)閥(fa)式避(bi)(bi)雷(lei)器(qi)或(huo)金屬(shu)氧(yang)化物避(bi)(bi)雷(lei)器(qi)。這種保護方式的(de)接(jie)線(xian)是：變(bian)壓器(qi)高低(di)避(bi)(bi)雷(lei)器(qi)的(de)接(jie)地線(xian)，低(di)壓側的(de)中性點(dian)和變(bian)壓器(qi)的(de)金屬(shu)外殼在四個(ge)(ge)點(dian)(或(huo)三個(ge)(ge)點(dian))連接(jie)到地面。

　　運行經(jing)驗和(he)實驗研究表明，對于(yu)具有良好絕緣性的(de)(de)配電(dian)(dian)(dian)(dian)變(bian)壓器(qi)(qi)，當(dang)避雷(lei)器(qi)(qi)安裝在高壓側(ce)時，仍(reng)會出現由正負過電(dian)(dian)(dian)(dian)壓引(yin)起的(de)(de)雷(lei)電(dian)(dian)(dian)(dian)事故。這是因為安裝在高壓側(ce)的(de)(de)避雷(lei)器(qi)(qi)對于(yu)正或負轉換過電(dian)(dian)(dian)(dian)壓是無(wu)能(neng)為力的(de)(de)。在正向(xiang)和(he)反(fan)(fan)向(xiang)變(bian)換的(de)(de)作用下的(de)(de)層間(jian)(jian)梯度與變(bian)壓器(qi)(qi)的(de)(de)匝數(shu)成比例(li)。它與繞組的(de)(de)分布有關。繞組的(de)(de)較好端，中間(jian)(jian)和(he)末端可能(neng)會損壞，但較終會更(geng)危險。安裝在低壓側(ce)的(de)(de)避雷(lei)器(qi)(qi)可以(yi)將(jiang)正向(xiang)和(he)反(fan)(fan)向(xiang)轉換過電(dian)(dian)(dian)(dian)壓限制在一(yi)定范圍(wei)內。

　　(3)高(gao)壓(ya)(ya)(ya)側和(he)低壓(ya)(ya)(ya)側接地的保(bao)護方(fang)(fang)法。該保(bao)護方(fang)(fang)式的接線是高(gao)壓(ya)(ya)(ya)側避雷器(qi)分別接地，低壓(ya)(ya)(ya)側未配備避雷器(qi)，低壓(ya)(ya)(ya)側中性(xing)點和(he)變壓(ya)(ya)(ya)器(qi)金屬外殼連接在一起，并分別接地從(cong)高(gao)壓(ya)(ya)(ya)側接地。