PRODUCT CLASSIFICATION
產品分類變壓器充電時應遵(zun)循以(yi)下原則:
一、應(ying)當從(cong)(cong)裝有保護的(de)電(dian)(dian)源側(ce)充(chong)電(dian)(dian),在兩側(ce)都(dou)有保護的(de)情(qing)況下,應(ying)從(cong)(cong)高壓(ya)側(ce)充(chong)電(dian)(dian)。具有高、中、低三(san)個電(dian)(dian)壓(ya)等級的(de)三(san)繞組(zu)電(dian)(dian)力變(bian)壓(ya)器(qi)不(bu)應(ying)從(cong)(cong)中壓(ya)側(ce)充(chong)電(dian)(dian)。充(chong)電(dian)(dian)時,變(bian)壓(ya)器(qi)中性點隔離開關必須投入接(jie)地。
A、變壓器停送電(dian)操作時,其(qi)中性點為(wei)什(shen)么一定要(yao)接地?這(zhe)主(zhu)要(yao)是為(wei)防止過電(dian)壓損壞被投退變壓器而(er)采取的一種措(cuo)施。
1、對于一側有(you)電(dian)源的受電(dian)變壓器(qi),當其開關非全(quan)相拉、合時,若其中性點不(bu)接(jie)地有(you)以下危險:
(1)變(bian)(bian)壓(ya)器電源側中性點對地電壓(ya)大可達相(xiang)電壓(ya),這可能(neng)損壞變(bian)(bian)壓(ya)器絕緣(yuan);
(2)變壓(ya)(ya)器的高、低壓(ya)(ya)線(xian)圈(quan)之(zhi)間有電容,這種電容會造(zao)成高壓(ya)(ya)對低壓(ya)(ya)的“傳遞過(guo)電壓(ya)(ya)”;
(3)當變壓(ya)器高低(di)壓(ya)線(xian)圈之間電(dian)容耦(ou)合,低(di)壓(ya)側會(hui)有(you)電(dian)壓(ya)達到諧振(zhen)條(tiao)件(jian)時(shi),可(ke)能會(hui)出現(xian)諧振(zhen)過電(dian)壓(ya),損壞絕(jue)緣。
2、對于低壓側有電源(yuan)的送(song)電變壓器(qi):
(1)由(you)于低壓(ya)(ya)側有電(dian)源(yuan),在并入系統前(qian),變壓(ya)(ya)器(qi)高(gao)壓(ya)(ya)側發(fa)生單相接地(di),若中性點未接地(di),則(ze)其中性點對地(di)電(dian)壓(ya)(ya)將是相電(dian)壓(ya)(ya),這可能損壞變壓(ya)(ya)器(qi)絕緣;
(2)非(fei)全(quan)相并入系(xi)統時,在(zai)一相與系(xi)統相聯時,由(you)于發電(dian)(dian)機和(he)系(xi)統的(de)頻(pin)率不(bu)同(tong),變(bian)壓(ya)器中性點(dian)又未接地,該變(bian)壓(ya)器中性點(dian)對(dui)地電(dian)(dian)壓(ya)gao將是二倍(bei)相電(dian)(dian)壓(ya),未合相的(de)電(dian)(dian)壓(ya)gao可達2.73倍(bei)相電(dian)(dian)壓(ya),將造(zao)成絕緣(yuan)損(sun)壞(huai)事故。
二、在(zai)一般情況下,電力變壓器投(tou)入運(yun)行,均(jun)應由發(fa)電機從(cong)零(ling)起升壓充(chong)電。