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

　　(1)在配(pei)電(dian)變壓(ya)(ya)(ya)(ya)(ya)器(qi)(qi)的(de)高壓(ya)(ya)(ya)(ya)(ya)側安裝避雷器(qi)(qi)。根據SDJ7-79“電(dian)力設備過(guo)電(dian)壓(ya)(ya)(ya)(ya)(ya)保護(hu)(hu)技術(shu)規(gui)定”：“配(pei)電(dian)變壓(ya)(ya)(ya)(ya)(ya)器(qi)(qi)的(de)高壓(ya)(ya)(ya)(ya)(ya)側一(yi)(yi)般(ban)應(ying)采用避雷器(qi)(qi)保護(hu)(hu)。避雷器(qi)(qi)的(de)接(jie)地線和低壓(ya)(ya)(ya)(ya)(ya)中性點變壓(ya)(ya)(ya)(ya)(ya)器(qi)(qi)的(de)電(dian)壓(ya)(ya)(ya)(ya)(ya)側和變壓(ya)(ya)(ya)(ya)(ya)器(qi)(qi)的(de)金屬外(wai)殼應(ying)連接(jie)在一(yi)(yi)起。“這(zhe)也是外(wai)交(jiao)部推薦的(de)防雷措施(shi)DL / T620-1997”交(jiao)流電(dian)氣裝置的(de)過(guo)電(dian)壓(ya)(ya)(ya)(ya)(ya)保護(hu)(hu)和絕(jue)緣(yuan)配(pei)合”。

　　然而，大(da)量的研究和操作(zuo)經(jing)驗表明，僅(jin)當(dang)避雷器用于高壓(ya)側(ce)(ce)時，仍然會(hui)受到雷電(dian)(dian)波(bo)的損(sun)壞。在一般(ban)地區(qu)，年損(sun)害(hai)率為1%，在多礦(kuang)區(qu)，可達到5%。在一些雷暴(bao)強度為100雷暴(bao)天的地區(qu)，年損(sun)害(hai)率高達50%。主要原因是雷電(dian)(dian)波(bo)侵入(ru)了配電(dian)(dian)變壓(ya)器高壓(ya)側(ce)(ce)繞組引(yin)起的正(zheng)負(fu)轉(zhuan)換過電(dian)(dian)壓(ya)。正(zheng)負(fu)轉(zhuan)換過壓(ya)產生(sheng)的機制如下(xia)：

　　1逆變換過電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)。也(ye)就是(shi)說(shuo)，當(dang)3到(dao)10kV時(shi)當(dang)側面侵入雷(lei)(lei)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)波(bo)(bo)并使避(bi)雷(lei)(lei)器工(gong)作時(shi)，大(da)(da)量(liang)的(de)(de)浪(lang)(lang)涌(yong)(yong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)流(liu)(liu)過接(jie)(jie)(jie)地(di)(di)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻(zu)以(yi)(yi)產生(sheng)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)降(jiang)。該電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)降(jiang)作用于(yu)(yu)低(di)(di)壓(ya)(ya)繞(rao)(rao)組(zu)(zu)(zu)的(de)(de)中(zhong)(zhong)性(xing)點，使得中(zhong)(zhong)性(xing)點電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)位(wei)(wei)(wei)上升，而(er)當(dang)低(di)(di)壓(ya)(ya)線(xian)相(xiang)(xiang)對較(jiao)長時(shi)，低(di)(di)壓(ya)(ya)線(xian)相(xiang)(xiang)當(dang)于(yu)(yu)波(bo)(bo)阻(zu)抗接(jie)(jie)(jie)地(di)(di)。因(yin)此，在(zai)(zai)中(zhong)(zhong)性(xing)點電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)位(wei)(wei)(wei)的(de)(de)作用下，低(di)(di)壓(ya)(ya)繞(rao)(rao)組(zu)(zu)(zu)流(liu)(liu)過大(da)(da)的(de)(de)浪(lang)(lang)涌(yong)(yong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)，在(zai)(zai)三相(xiang)(xiang)繞(rao)(rao)組(zu)(zu)(zu)中(zhong)(zhong)流(liu)(liu)動的(de)(de)浪(lang)(lang)涌(yong)(yong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)具有相(xiang)(xiang)同(tong)(tong)的(de)(de)方(fang)向(xiang)和(he)(he)相(xiang)(xiang)同(tong)(tong)的(de)(de)大(da)(da)小，由(you)它(ta)們產生(sheng)的(de)(de)磁通(tong)量(liang)是(shi)根據變壓(ya)(ya)器匝數比(bi)在(zai)(zai)高(gao)(gao)壓(ya)(ya)繞(rao)(rao)組(zu)(zu)(zu)中(zhong)(zhong)感應出(chu)。脈(mo)沖(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)位(wei)(wei)(wei)非常高(gao)(gao)。三相(xiang)(xiang)脈(mo)沖(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)位(wei)(wei)(wei)具有相(xiang)(xiang)同(tong)(tong)的(de)(de)方(fang)向(xiang)和(he)(he)相(xiang)(xiang)同(tong)(tong)的(de)(de)尺寸。由(you)于(yu)(yu)高(gao)(gao)壓(ya)(ya)繞(rao)(rao)組(zu)(zu)(zu)以(yi)(yi)星(xing)形連接(jie)(jie)(jie)而(er)中(zhong)(zhong)性(xing)點未接(jie)(jie)(jie)地(di)(di)，所(suo)以(yi)(yi)在(zai)(zai)高(gao)(gao)壓(ya)(ya)繞(rao)(rao)組(zu)(zu)(zu)中(zhong)(zhong)，盡管存(cun)在(zai)(zai)脈(mo)沖(chong)(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)位(wei)(wei)(wei)，但沒有浪(lang)(lang)涌(yong)(yong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)。浪(lang)(lang)涌(yong)(yong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)僅在(zai)(zai)低(di)(di)壓(ya)(ya)繞(rao)(rao)組(zu)(zu)(zu)中(zhong)(zhong)流(liu)(liu)動，并且高(gao)(gao)壓(ya)(ya)繞(rao)(rao)組(zu)(zu)(zu)中(zhong)(zhong)沒有相(xiang)(xiang)應的(de)(de)浪(lang)(lang)涌(yong)(yong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)來平衡(heng)。因(yin)此，低(di)(di)壓(ya)(ya)繞(rao)(rao)組(zu)(zu)(zu)中(zhong)(zhong)的(de)(de)浪(lang)(lang)涌(yong)(yong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)全部變為(wei)勵磁電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)，產生(sheng)大(da)(da)的(de)(de)零序磁通(tong)，從(cong)而(er)高(gao)(gao)壓(ya)(ya)側產生(sheng)高(gao)(gao)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)位(wei)(wei)(wei)。由(you)于(yu)(yu)高(gao)(gao)壓(ya)(ya)繞(rao)(rao)組(zu)(zu)(zu)輸出(chu)端(duan)的(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)位(wei)(wei)(wei)由(you)避(bi)雷(lei)(lei)器的(de)(de)剩余電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)決定，因(yin)此該感應電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)位(wei)(wei)(wei)沿繞(rao)(rao)組(zu)(zu)(zu)分(fen)布，振幅在(zai)(zai)中(zhong)(zhong)性(xing)點處(chu)較(jiao)大(da)(da)。因(yin)此，中(zhong)(zhong)性(xing)點絕緣容易破壞。同(tong)(tong)時(shi)，層(ceng)和(he)(he)匝之間的(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)位(wei)(wei)(wei)梯(ti)度相(xiang)(xiang)應地(di)(di)增(zeng)加(jia)，并且在(zai)(zai)其他(ta)位(wei)(wei)(wei)置(zhi)處(chu)可能發生(sheng)層(ceng)間和(he)(he)匝間絕緣擊穿。這種過電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)先先是(shi)由(you)高(gao)(gao)壓(ya)(ya)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)波(bo)(bo)引(yin)起的(de)(de)，然后(hou)是(shi)通(tong)過低(di)(di)壓(ya)(ya)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)磁感應到(dao)高(gao)(gao)壓(ya)(ya)繞(rao)(rao)組(zu)(zu)(zu)，通(tong)常稱為(wei)逆變換。

　　2正(zheng)轉換過(guo)(guo)壓(ya)(ya)(ya)。所(suo)謂的(de)正(zheng)過(guo)(guo)電(dian)壓(ya)(ya)(ya)，即當雷(lei)電(dian)波(bo)被低壓(ya)(ya)(ya)線(xian)侵入(ru)時(shi)，配電(dian)變(bian)壓(ya)(ya)(ya)器的(de)低壓(ya)(ya)(ya)繞組有一(yi)個浪(lang)涌(yong)電(dian)流，浪(lang)涌(yong)電(dian)流也會產生(sheng)(sheng)感(gan)應電(dian)動勢(shi)。根據匝(za)數比的(de)高壓(ya)(ya)(ya)繞組，使得高壓(ya)(ya)(ya)側(ce)中性點電(dian)位It大大提高，并(bing)且(qie)層(ceng)(ceng)和匝(za)之間(jian)的(de)梯度(du)電(dian)壓(ya)(ya)(ya)也相應地增加。由(you)于低電(dian)壓(ya)(ya)(ya)入(ru)射波(bo)而在高壓(ya)(ya)(ya)側(ce)產生(sheng)(sheng)感(gan)應過(guo)(guo)電(dian)壓(ya)(ya)(ya)的(de)過(guo)(guo)程稱為(wei)正(zheng)向變(bian)換。試驗表明，當低壓(ya)(ya)(ya)輸入(ru)波(bo)為(wei)10kV，接(jie)地電(dian)阻(zu)為(wei)5Ω時(shi)，高壓(ya)(ya)(ya)繞組上的(de)層(ceng)(ceng)間(jian)梯度(du)電(dian)壓(ya)(ya)(ya)超過(guo)(guo)配電(dian)變(bian)壓(ya)(ya)(ya)器的(de)層(ceng)(ceng)間(jian)絕緣全波(bo)沖擊強(qiang)度(du)一(yi)倍以(yi)上。在這種情況下，變(bian)壓(ya)(ya)(ya)器層(ceng)(ceng)間(jian)絕緣絕對(dui)要穿透。

　　(2)在(zai)配電(dian)變壓器(qi)的(de)(de)(de)低壓側(ce)安裝普通(tong)閥(fa)式(shi)避(bi)雷(lei)器(qi)或金屬(shu)氧化(hua)物避(bi)雷(lei)器(qi)。這種保護方式(shi)的(de)(de)(de)接線是：變壓器(qi)高(gao)低避(bi)雷(lei)器(qi)的(de)(de)(de)接地線，低壓側(ce)的(de)(de)(de)中性點和變壓器(qi)的(de)(de)(de)金屬(shu)外殼在(zai)四個點(或三個點)連接到地面。

　　運行(xing)經驗和(he)實(shi)驗研究表明(ming)，對于具有良好(hao)絕緣性的(de)(de)(de)(de)配電(dian)變(bian)壓(ya)(ya)器(qi)，當避雷器(qi)安(an)裝(zhuang)(zhuang)在(zai)高壓(ya)(ya)側(ce)時(shi)，仍會出現由正(zheng)負(fu)過電(dian)壓(ya)(ya)引起的(de)(de)(de)(de)雷電(dian)事(shi)故(gu)。這是因為安(an)裝(zhuang)(zhuang)在(zai)高壓(ya)(ya)側(ce)的(de)(de)(de)(de)避雷器(qi)對于正(zheng)或負(fu)轉換過電(dian)壓(ya)(ya)是無能(neng)(neng)為力的(de)(de)(de)(de)。在(zai)正(zheng)向(xiang)和(he)反(fan)向(xiang)變(bian)換的(de)(de)(de)(de)作(zuo)用下的(de)(de)(de)(de)層間梯度與變(bian)壓(ya)(ya)器(qi)的(de)(de)(de)(de)匝數成比(bi)例。它與繞組的(de)(de)(de)(de)分布有關。繞組的(de)(de)(de)(de)較(jiao)好(hao)端，中(zhong)間和(he)末(mo)端可(ke)能(neng)(neng)會損(sun)壞(huai)，但較(jiao)終會更危險。安(an)裝(zhuang)(zhuang)在(zai)低壓(ya)(ya)側(ce)的(de)(de)(de)(de)避雷器(qi)可(ke)以將正(zheng)向(xiang)和(he)反(fan)向(xiang)轉換過電(dian)壓(ya)(ya)限制(zhi)在(zai)一定范圍(wei)內。

　　(3)高壓(ya)(ya)(ya)側(ce)和低壓(ya)(ya)(ya)側(ce)接地的(de)保(bao)(bao)護方法。該保(bao)(bao)護方式的(de)接線是(shi)高壓(ya)(ya)(ya)側(ce)避雷(lei)器(qi)(qi)分別接地，低壓(ya)(ya)(ya)側(ce)未配備避雷(lei)器(qi)(qi)，低壓(ya)(ya)(ya)側(ce)中性點(dian)和變壓(ya)(ya)(ya)器(qi)(qi)金屬外殼(ke)連接在一起，并分別接地從高壓(ya)(ya)(ya)側(ce)接地。