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(shi)變壓(ya)器

　　(1)在配(pei)電(dian)變壓(ya)(ya)(ya)(ya)器(qi)(qi)的(de)高壓(ya)(ya)(ya)(ya)側安裝(zhuang)(zhuang)避雷(lei)器(qi)(qi)。根據(ju)SDJ7-79“電(dian)力設備過(guo)(guo)電(dian)壓(ya)(ya)(ya)(ya)保(bao)護(hu)技(ji)術規定”：“配(pei)電(dian)變壓(ya)(ya)(ya)(ya)器(qi)(qi)的(de)高壓(ya)(ya)(ya)(ya)側一般應(ying)采(cai)用(yong)避雷(lei)器(qi)(qi)保(bao)護(hu)。避雷(lei)器(qi)(qi)的(de)接地線和低壓(ya)(ya)(ya)(ya)中性點變壓(ya)(ya)(ya)(ya)器(qi)(qi)的(de)電(dian)壓(ya)(ya)(ya)(ya)側和變壓(ya)(ya)(ya)(ya)器(qi)(qi)的(de)金屬外殼應(ying)連接在一起。“這也是外交(jiao)部推薦(jian)的(de)防雷(lei)措施DL / T620-1997”交(jiao)流電(dian)氣(qi)裝(zhuang)(zhuang)置的(de)過(guo)(guo)電(dian)壓(ya)(ya)(ya)(ya)保(bao)護(hu)和絕緣配(pei)合”。

　　然(ran)而，大量的(de)(de)研(yan)究和操作經驗表明，僅當避雷器用(yong)于高壓(ya)側時，仍然(ran)會受到(dao)雷電波(bo)的(de)(de)損(sun)(sun)壞。在一般(ban)地(di)區，年損(sun)(sun)害(hai)(hai)率(lv)為1%，在多(duo)礦區，可達到(dao)5%。在一些雷暴(bao)強度為100雷暴(bao)天的(de)(de)地(di)區，年損(sun)(sun)害(hai)(hai)率(lv)高達50%。主要原因是雷電波(bo)侵入了配電變壓(ya)器高壓(ya)側繞(rao)組引起的(de)(de)正(zheng)負(fu)轉(zhuan)換(huan)過電壓(ya)。正(zheng)負(fu)轉(zhuan)換(huan)過壓(ya)產生的(de)(de)機制如下(xia)：

　　1逆變(bian)(bian)換(huan)過(guo)電(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)。也就是說，當(dang)3到10kV時(shi)當(dang)側面侵(qin)入雷(lei)電(dian)(dian)(dian)波并(bing)(bing)使避(bi)雷(lei)器工作(zuo)時(shi)，大(da)(da)量(liang)的(de)(de)(de)浪(lang)(lang)涌(yong)電(dian)(dian)(dian)流(liu)(liu)(liu)流(liu)(liu)(liu)過(guo)接(jie)(jie)地電(dian)(dian)(dian)阻以(yi)產(chan)生(sheng)電(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)降。該電(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)降作(zuo)用(yong)于低(di)(di)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)繞組(zu)(zu)(zu)的(de)(de)(de)中(zhong)(zhong)性(xing)(xing)點，使得中(zhong)(zhong)性(xing)(xing)點電(dian)(dian)(dian)位(wei)上升，而當(dang)低(di)(di)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)線相(xiang)對較長時(shi)，低(di)(di)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)線相(xiang)當(dang)于波阻抗接(jie)(jie)地。因(yin)此(ci)，在(zai)(zai)(zai)中(zhong)(zhong)性(xing)(xing)點電(dian)(dian)(dian)位(wei)的(de)(de)(de)作(zuo)用(yong)下，低(di)(di)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)繞組(zu)(zu)(zu)流(liu)(liu)(liu)過(guo)大(da)(da)的(de)(de)(de)浪(lang)(lang)涌(yong)電(dian)(dian)(dian)流(liu)(liu)(liu)，在(zai)(zai)(zai)三(san)相(xiang)繞組(zu)(zu)(zu)中(zhong)(zhong)流(liu)(liu)(liu)動的(de)(de)(de)浪(lang)(lang)涌(yong)電(dian)(dian)(dian)流(liu)(liu)(liu)具(ju)有(you)相(xiang)同(tong)的(de)(de)(de)方向和相(xiang)同(tong)的(de)(de)(de)大(da)(da)小，由(you)(you)它們產(chan)生(sheng)的(de)(de)(de)磁通量(liang)是根(gen)據(ju)變(bian)(bian)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)器匝(za)(za)數比在(zai)(zai)(zai)高(gao)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)繞組(zu)(zu)(zu)中(zhong)(zhong)感應出。脈(mo)沖(chong)電(dian)(dian)(dian)位(wei)非常高(gao)。三(san)相(xiang)脈(mo)沖(chong)電(dian)(dian)(dian)位(wei)具(ju)有(you)相(xiang)同(tong)的(de)(de)(de)方向和相(xiang)同(tong)的(de)(de)(de)尺寸。由(you)(you)于高(gao)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)繞組(zu)(zu)(zu)以(yi)星形連接(jie)(jie)而中(zhong)(zhong)性(xing)(xing)點未接(jie)(jie)地，所以(yi)在(zai)(zai)(zai)高(gao)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)繞組(zu)(zu)(zu)中(zhong)(zhong)，盡管存在(zai)(zai)(zai)脈(mo)沖(chong)電(dian)(dian)(dian)位(wei)，但沒(mei)有(you)浪(lang)(lang)涌(yong)電(dian)(dian)(dian)流(liu)(liu)(liu)。浪(lang)(lang)涌(yong)電(dian)(dian)(dian)流(liu)(liu)(liu)僅(jin)在(zai)(zai)(zai)低(di)(di)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)繞組(zu)(zu)(zu)中(zhong)(zhong)流(liu)(liu)(liu)動，并(bing)(bing)且(qie)高(gao)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)繞組(zu)(zu)(zu)中(zhong)(zhong)沒(mei)有(you)相(xiang)應的(de)(de)(de)浪(lang)(lang)涌(yong)電(dian)(dian)(dian)流(liu)(liu)(liu)來平衡。因(yin)此(ci)，低(di)(di)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)繞組(zu)(zu)(zu)中(zhong)(zhong)的(de)(de)(de)浪(lang)(lang)涌(yong)電(dian)(dian)(dian)流(liu)(liu)(liu)全部變(bian)(bian)為勵磁電(dian)(dian)(dian)流(liu)(liu)(liu)，產(chan)生(sheng)大(da)(da)的(de)(de)(de)零序磁通，從而高(gao)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)側產(chan)生(sheng)高(gao)電(dian)(dian)(dian)位(wei)。由(you)(you)于高(gao)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)繞組(zu)(zu)(zu)輸出端的(de)(de)(de)電(dian)(dian)(dian)位(wei)由(you)(you)避(bi)雷(lei)器的(de)(de)(de)剩余電(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)決(jue)定，因(yin)此(ci)該感應電(dian)(dian)(dian)位(wei)沿繞組(zu)(zu)(zu)分布，振幅在(zai)(zai)(zai)中(zhong)(zhong)性(xing)(xing)點處較大(da)(da)。因(yin)此(ci)，中(zhong)(zhong)性(xing)(xing)點絕(jue)緣容易破壞(huai)。同(tong)時(shi)，層(ceng)和匝(za)(za)之間(jian)的(de)(de)(de)電(dian)(dian)(dian)位(wei)梯度(du)相(xiang)應地增加，并(bing)(bing)且(qie)在(zai)(zai)(zai)其他(ta)位(wei)置處可能(neng)發生(sheng)層(ceng)間(jian)和匝(za)(za)間(jian)絕(jue)緣擊穿。這種(zhong)過(guo)電(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)先先是由(you)(you)高(gao)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)電(dian)(dian)(dian)波引(yin)起(qi)的(de)(de)(de)，然(ran)后是通過(guo)低(di)(di)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)電(dian)(dian)(dian)磁感應到高(gao)壓(ya)(ya)(ya)(ya)(ya)(ya)(ya)繞組(zu)(zu)(zu)，通常稱為逆變(bian)(bian)換(huan)。

　　2正(zheng)轉換(huan)過(guo)(guo)(guo)壓(ya)(ya)(ya)。所謂的(de)正(zheng)過(guo)(guo)(guo)電(dian)(dian)壓(ya)(ya)(ya)，即當(dang)雷電(dian)(dian)波被(bei)低(di)壓(ya)(ya)(ya)線侵(qin)入(ru)時，配電(dian)(dian)變(bian)壓(ya)(ya)(ya)器的(de)低(di)壓(ya)(ya)(ya)繞(rao)組有一個浪(lang)涌電(dian)(dian)流，浪(lang)涌電(dian)(dian)流也會產生感(gan)應電(dian)(dian)動勢。根據匝數比(bi)的(de)高壓(ya)(ya)(ya)繞(rao)組，使(shi)得(de)高壓(ya)(ya)(ya)側中性點電(dian)(dian)位It大大提高，并且層和(he)匝之間(jian)(jian)的(de)梯度電(dian)(dian)壓(ya)(ya)(ya)也相應地(di)(di)增加(jia)。由于低(di)電(dian)(dian)壓(ya)(ya)(ya)入(ru)射波而(er)在高壓(ya)(ya)(ya)側產生感(gan)應過(guo)(guo)(guo)電(dian)(dian)壓(ya)(ya)(ya)的(de)過(guo)(guo)(guo)程稱為正(zheng)向變(bian)換(huan)。試驗表明，當(dang)低(di)壓(ya)(ya)(ya)輸入(ru)波為10kV，接(jie)地(di)(di)電(dian)(dian)阻為5Ω時，高壓(ya)(ya)(ya)繞(rao)組上(shang)的(de)層間(jian)(jian)梯度電(dian)(dian)壓(ya)(ya)(ya)超(chao)過(guo)(guo)(guo)配電(dian)(dian)變(bian)壓(ya)(ya)(ya)器的(de)層間(jian)(jian)絕(jue)緣全波沖擊強度一倍以上(shang)。在這種情(qing)況下，變(bian)壓(ya)(ya)(ya)器層間(jian)(jian)絕(jue)緣絕(jue)對(dui)要穿透。

　　(2)在配電變(bian)壓(ya)器(qi)的(de)低壓(ya)側安裝普通閥式避(bi)雷(lei)器(qi)或(huo)(huo)金屬氧化物避(bi)雷(lei)器(qi)。這種保護方式的(de)接(jie)(jie)線是：變(bian)壓(ya)器(qi)高低避(bi)雷(lei)器(qi)的(de)接(jie)(jie)地線，低壓(ya)側的(de)中性點和變(bian)壓(ya)器(qi)的(de)金屬外殼在四個點(或(huo)(huo)三個點)連(lian)接(jie)(jie)到地面。

　　運(yun)行經驗和(he)實(shi)驗研究(jiu)表明，對于(yu)具(ju)有(you)良好絕緣性的配電(dian)變(bian)壓(ya)器(qi)(qi)，當避(bi)雷(lei)(lei)器(qi)(qi)安(an)裝在(zai)(zai)(zai)高(gao)壓(ya)側(ce)(ce)時，仍(reng)會(hui)出現(xian)由正(zheng)負(fu)過電(dian)壓(ya)引(yin)起的雷(lei)(lei)電(dian)事故。這是(shi)因為(wei)安(an)裝在(zai)(zai)(zai)高(gao)壓(ya)側(ce)(ce)的避(bi)雷(lei)(lei)器(qi)(qi)對于(yu)正(zheng)或負(fu)轉換過電(dian)壓(ya)是(shi)無能為(wei)力的。在(zai)(zai)(zai)正(zheng)向和(he)反(fan)向變(bian)換的作用下的層間梯度與變(bian)壓(ya)器(qi)(qi)的匝數成比(bi)例。它與繞組(zu)的分布有(you)關。繞組(zu)的較(jiao)好端(duan)，中間和(he)末端(duan)可(ke)能會(hui)損壞，但較(jiao)終會(hui)更(geng)危(wei)險。安(an)裝在(zai)(zai)(zai)低(di)壓(ya)側(ce)(ce)的避(bi)雷(lei)(lei)器(qi)(qi)可(ke)以將(jiang)正(zheng)向和(he)反(fan)向轉換過電(dian)壓(ya)限制在(zai)(zai)(zai)一定范圍內。

　　(3)高(gao)壓(ya)側(ce)和低(di)(di)壓(ya)側(ce)接(jie)地(di)(di)的(de)保護方法。該保護方式的(de)接(jie)線是(shi)高(gao)壓(ya)側(ce)避雷器(qi)分別接(jie)地(di)(di)，低(di)(di)壓(ya)側(ce)未配備避雷器(qi)，低(di)(di)壓(ya)側(ce)中性點和變壓(ya)器(qi)金屬外殼連接(jie)在一(yi)起，并分別接(jie)地(di)(di)從高(gao)壓(ya)側(ce)接(jie)地(di)(di)。