隨著(zhu)"西(xi)電(dian)(dian)東送(song)"、"南電(dian)(dian)北(bei)送(song)"等工程的推進，高(gao)壓直流電(dian)(dian)纜將成被應用的主力軍。新能源規模(mo)化接(jie)入及(ji)城(cheng)市輸電(dian)(dian)的電(dian)(dian)纜化建設，都(dou)需要(yao)應用高(gao)壓直流電(dian)(dian)纜。高(gao)壓直流電(dian)(dian)纜更是(shi)海上風(feng)電(dian)(dian)、海上孤島的*輸電(dian)(dian)手段。

　　 高(gao)壓及超高(gao)壓電(dian)(dian)纜已成(cheng)為現代城市電(dian)(dian)網(wang)項目工程中不可或缺的材料，但我國高(gao)壓超高(gao)壓電(dian)(dian)纜領域起步(bu)晚，材料、設(she)備(bei)及制造技術長(chang)期(qi)以來主要(yao)依賴引進和模仿。下面我們就來說說，高(gao)壓電(dian)(dian)纜進行直流耐壓試(shi)驗(yan)的問題主要(yao)表現在哪些個(ge)方面？

　　 1.直(zhi)流(liu)電(dian)(dian)(dian)(dian)(dian)壓下(xia)(xia)，電(dian)(dian)(dian)(dian)(dian)纜(lan)(lan)絕(jue)緣的(de)(de)電(dian)(dian)(dian)(dian)(dian)場(chang)分(fen)布(bu)取決(jue)于材料的(de)(de)體積電(dian)(dian)(dian)(dian)(dian)阻率，而交(jiao)流(liu)電(dian)(dian)(dian)(dian)(dian)壓下(xia)(xia)的(de)(de)電(dian)(dian)(dian)(dian)(dian)場(chang)分(fen)布(bu)取決(jue)于各介質的(de)(de)介電(dian)(dian)(dian)(dian)(dian)常數，特別是在(zai)電(dian)(dian)(dian)(dian)(dian)纜(lan)(lan)終端(duan)頭、接頭盒等電(dian)(dian)(dian)(dian)(dian)纜(lan)(lan)附件(jian)中的(de)(de)直(zhi)流(liu)電(dian)(dian)(dian)(dian)(dian)場(chang)強(qiang)度(du)的(de)(de)分(fen)布(bu)和(he)交(jiao)流(liu)電(dian)(dian)(dian)(dian)(dian)場(chang)強(qiang)度(du)的(de)(de)分(fen)布(bu)完全不(bu)同(tong)(tong)，而且直(zhi)流(liu)電(dian)(dian)(dian)(dian)(dian)壓下(xia)(xia)絕(jue)緣老(lao)化(hua)的(de)(de)機理和(he)交(jiao)流(liu)電(dian)(dian)(dian)(dian)(dian)壓下(xia)(xia)的(de)(de)老(lao)化(hua)機理不(bu)相(xiang)同(tong)(tong)。因(yin)此，直(zhi)流(liu)耐壓試驗不(bu)能模擬高壓電(dian)(dian)(dian)(dian)(dian)纜(lan)(lan)的(de)(de)運行工況。

　　 2.高壓(ya)電(dian)(dian)(dian)(dian)(dian)纜(lan)在直(zhi)(zhi)流電(dian)(dian)(dian)(dian)(dian)壓(ya)下(xia)會(hui)產生"記憶(yi)"效(xiao)應，存儲(chu)積累(lei)單極(ji)性殘余(yu)電(dian)(dian)(dian)(dian)(dian)荷(he)。一(yi)旦有了由于直(zhi)(zhi)流耐壓(ya)試驗引起的(de)"記憶(yi)性"，需要很長時間才能將這種直(zhi)(zhi)流偏壓(ya)釋放(fang)。電(dian)(dian)(dian)(dian)(dian)纜(lan)如果在直(zhi)(zhi)流殘余(yu)電(dian)(dian)(dian)(dian)(dian)荷(he)未完全釋放(fang)之前投(tou)入運行(xing)，直(zhi)(zhi)流偏壓(ya)便會(hui)疊加在工(gong)頻(pin)電(dian)(dian)(dian)(dian)(dian)壓(ya)峰值上，使得電(dian)(dian)(dian)(dian)(dian)纜(lan)上的(de)電(dian)(dian)(dian)(dian)(dian)壓(ya)值遠遠超(chao)過其額(e)定電(dian)(dian)(dian)(dian)(dian)壓(ya)，從而有可能導致電(dian)(dian)(dian)(dian)(dian)纜(lan)絕緣擊穿(chuan)。

　　 3.直(zhi)流(liu)耐(nai)壓試驗時，會有(you)電(dian)(dian)(dian)子(zi)注入到聚(ju)合物介(jie)質(zhi)內部，形成空間電(dian)(dian)(dian)荷，使該處(chu)的(de)(de)電(dian)(dian)(dian)場強度降低，從(cong)而難于發(fa)(fa)生擊穿(chuan)。高(gao)壓電(dian)(dian)(dian)纜(lan)(lan)(lan)的(de)(de)半導體凸(tu)出處(chu)和污穢(hui)點(dian)(dian)等處(chu)容易產(chan)生空間電(dian)(dian)(dian)荷。但如果在試驗時電(dian)(dian)(dian)纜(lan)(lan)(lan)終端頭發(fa)(fa)生表面(mian)閃絡或(huo)電(dian)(dian)(dian)纜(lan)(lan)(lan)附件擊穿(chuan)，會造(zao)成電(dian)(dian)(dian)纜(lan)(lan)(lan)芯線上產(chan)生波振蕩(dang)，在已積聚(ju)空間電(dian)(dian)(dian)荷的(de)(de)地(di)點(dian)(dian)，由(you)于振蕩(dang)電(dian)(dian)(dian)壓極性迅速改變(bian)為(wei)異極性，使該處(chu)電(dian)(dian)(dian)場強度顯著增大(da)，可能(neng)損(sun)壞絕緣(yuan)，造(zao)成多(duo)點(dian)(dian)擊穿(chuan)。

　　 4.高壓(ya)電(dian)(dian)(dian)纜致命的一個弱點(dian)是絕(jue)緣內(nei)易產生(sheng)水樹(shu)枝(zhi)，一旦(dan)產生(sheng)水樹(shu)枝(zhi)，在(zai)直流(liu)電(dian)(dian)(dian)壓(ya)下會迅速轉變(bian)為電(dian)(dian)(dian)樹(shu)枝(zhi)，并形成放(fang)電(dian)(dian)(dian)，加速了絕(jue)緣劣化(hua)，以致于運(yun)行后(hou)在(zai)工(gong)頻電(dian)(dian)(dian)壓(ya)作(zuo)用下形成擊穿(chuan)。而單純(chun)的水樹(shu)枝(zhi)在(zai)交(jiao)流(liu)工(gong)作(zuo)電(dian)(dian)(dian)壓(ya)下還能保持相當的耐壓(ya)值，并能保持一段時間。

　　 生(sheng)命安全(quan)高(gao)于一切，高(gao)壓(ya)低(di)壓(ya)耐火電纜(lan)因(yin)其獨(du)特(te)優勢在(zai)高(gao)層建筑、地下鐵道、地下街、大型電站及重要的工礦企業等與防火安全(quan)和消防救生(sheng)有(you)關的地方得到廣泛應用。我(wo)們(men)相信因(yin)線纜(lan)問題引起的事故會越來(lai)越少。