油浸式變壓器廠家解釋油浸式變壓器過電壓現象簡要分析：
 
(1)操作過電壓
在一般(ban)配(pei)電(dian)網中，使用的絕大多數是(shi)降(jiang)壓(ya)變(bian)(bian)壓(ya)器(qi)，下面就以降(jiang)壓(ya)變(bian)(bian)壓(ya)器(qi)空載拉(la)閘操作為(wei)例說明操作過電(dian)壓(ya)產生的原因。

在定性分析時(shi)，匝(za)間電(dian)(dian)(dian)(dian)容(rong)的(de)影響可略去不計。空(kong)載變壓(ya)(ya)器從電(dian)(dian)(dian)(dian)網(wang)上拉閘時(shi)，如果空(kong)載電(dian)(dian)(dian)(dian)流的(de)瞬(shun)時(shi)值(zhi)不等(deng)于零而(er)是(shi)某一數值(zhi)Ia，這時(shi)相應(ying)的(de)外施(shi)電(dian)(dian)(dian)(dian)壓(ya)(ya)瞬(shun)時(shi)值(zhi)為Ua。于是(shi)在拉閘操作瞬(shun)間，電(dian)(dian)(dian)(dian)感L1中儲藏的(de)磁場(chang)能量為1/2Ll?I2a,電(dian)(dian)(dian)(dian)容(rong)C’Fe上儲藏的(de)電(dian)(dian)(dian)(dian)場(chang)能量為1/2C’FeU2a。

由(you)(you)于這時(shi)變壓器的(de)(de)(de)電(dian)路是由(you)(you)電(dian)感L1電(dian)容(rong)C’Fe并聯的(de)(de)(de)電(dian)路，故在(zai)拉閘操(cao)作瞬間(jian)，回路內將發生電(dian)磁(ci)振蕩過(guo)(guo)程。在(zai)振蕩過(guo)(guo)程中(zhong)，當某(mou)一瞬間(jian)電(dian)流(liu)等于零時(shi)，此時(shi)磁(ci)場(chang)能量全部轉化為電(dian)場(chang)能量，由(you)(you)電(dian)容(rong)吸(xi)收，電(dian)容(rong)上的(de)(de)(de)電(dian)壓便升高到最大(da)值Ucmax。當拉閘操(cao)作電(dian)流(liu)和電(dian)容(rong)上的(de)(de)(de)電(dian)壓一定時(shi)，繞組的(de)(de)(de)電(dian)感愈(yu)大(da)，對地電(dian)容(rong)愈(yu)小(xiao)，則拉閘操(cao)作過(guo)(guo)電(dian)壓愈(yu)高。在(zai)電(dian)力系(xi)統中(zhong)，操(cao)作過(guo)(guo)電(dian)壓通常不(bu)超過(guo)(guo)額定電(dian)壓的(de)(de)(de)30一4.5倍。

(2)大(da)氣過電(dian)壓

大氣過(guo)電(dian)(dian)壓(ya)(ya)是由(you)輸電(dian)(dian)線路(lu)(lu)直接遭受(shou)雷(lei)(lei)擊或(huo)雷(lei)(lei)云放電(dian)(dian)時(shi)，電(dian)(dian)磁場的劇烈變化所引起的。當輸電(dian)(dian)線路(lu)(lu)直接遭受(shou)雷(lei)(lei)擊時(shi)，雷(lei)(lei)云所帶的大量(liang)電(dian)(dian)荷(he)(設為(wei)正電(dian)(dian)荷(he))通過(guo)放電(dian)(dian)渠道落(luo)到輸電(dian)(dian)線上(shang)，大量(liang)的自(zi)由(you)電(dian)(dian)荷(he)向輸電(dian)(dian)線路(lu)(lu)的兩端傳播，就在輸電(dian)(dian)線上(shang)引起沖擊過(guo)電(dian)(dian)壓(ya)(ya)，稱(cheng)為(wei)雷(lei)(lei)電(dian)(dian)過(guo)電(dian)(dian)壓(ya)(ya)。雷(lei)(lei)電(dian)(dian)波(bo)由(you)零上(shang)升到最大值這(zhe)一段稱(cheng)為(wei)波(bo)頭，下降部分稱(cheng)為(wei)波(bo)尾。

如果(guo)把波(bo)頭所占(zhan)時間看成是周(zhou)期波(bo)的(de)1/4周(zhou)期，則雷電(dian)(dian)(dian)(dian)波(bo)可看成是頻(pin)(pin)率極(ji)高的(de)周(zhou)期性波(bo)。這(zhe)樣(yang)，當(dang)過電(dian)(dian)(dian)(dian)壓(ya)波(bo)到(dao)達(da)變壓(ya)器(qi)接線端時，相當(dang)于(yu)給變壓(ya)器(qi)加上了一個(ge)頻(pin)(pin)率極(ji)高的(de)高電(dian)(dian)(dian)(dian)壓(ya)。這(zhe)一瞬變過程很快，一開始，由(you)(you)于(yu)在(zai)高頻(pin)(pin)下wL很大，因(yin)此，1/wC很小，電(dian)(dian)(dian)(dian)流只從高壓(ya)繞(rao)組(zu)(zu)的(de)匝電(dian)(dian)(dian)(dian)容(rong)和對地電(dian)(dian)(dian)(dian)容(rong)中(zhong)流過。由(you)(you)于(yu)低壓(ya)繞(rao)組(zu)(zu)靠近(jin)鐵心，它對地電(dian)(dian)(dian)(dian)容(rong)很大 (即容(rong)抗很小)，可近(jin)似(si)地認(ren)為低壓(ya)繞(rao)組(zu)(zu)接地。

當雷電(dian)(dian)波襲擊時(shi)，沿繞組高度(du)上的電(dian)(dian)壓分布(bu)取決于匝(za)間電(dian)(dian)容(rong)(rong)(rong)C’Fe，和對(dui)地電(dian)(dian)容(rong)(rong)(rong)C’Fe的比例(li)。在一般情況下，由于兩種電(dian)(dian)容(rong)(rong)(rong)都(dou)存在，過電(dian)(dian)壓時(shi)，一部(bu)分電(dian)(dian)流(liu)(liu)由對(dui)地電(dian)(dian)容(rong)(rong)(rong)分流(liu)(liu)，故每個匝(za)間電(dian)(dian)容(rong)(rong)(rong)流(liu)(liu)的電(dian)(dian)流(liu)(liu)不相等，靠近(jin)輸(shu)電(dian)(dian)線端的匝(za)間電(dian)(dian)容(rong)(rong)(rong)流(liu)(liu)過的電(dian)(dian)流(liu)(liu)最大，越(yue)往(wang)后則(ze)越(yue)小(xiao)。

隨(sui)著電(dian)壓沿繞組高(gao)度的(de)分布(bu)變為不均勻，起始電(dian)壓分布(bu)很不均勻，靠近輸電(dian)線端的(de)前幾匝(za)間(jian)出現很大(da)的(de)電(dian)壓梯度，因(yin)此，在(zai)靠近輸電(dian)線端的(de)前幾個線匝(za)里(li)，匝(za)間(jian)絕緣受到很大(da)的(de)威脅，這(zhe)時最高(gao)匝(za)間(jian)電(dian)壓可能(neng)高(gao)達額定電(dian)壓的(de)50一200倍(bei)。