絕緣是將絕緣材料(liao)按其耐受(shou)電(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)程度的(de)要求，以(yi)不同的(de)厚度包(bao)(bao)復在導體(ti)外面而成，起著使(shi)帶電(dian)(dian)(dian)(dian)(dian)體(ti)與其他部分隔(ge)絕的(de)作用(yong)(yong)(yong)。絞合線芯(xin)可以(yi)采(cai)(cai)用(yong)(yong)(yong)非緊(jin)壓(ya)(ya)(ya)(ya)和緊(jin)壓(ya)(ya)(ya)(ya)線芯(xin)兩種。交(jiao)聯(lian)電(dian)(dian)(dian)(dian)(dian)纜(lan) 的(de)導電(dian)(dian)(dian)(dian)(dian)線芯(xin)通常采(cai)(cai)用(yong)(yong)(yong)絞合結構，1kV交(jiao)聯(lian)電(dian)(dian)(dian)(dian)(dian)纜(lan)通常采(cai)(cai)用(yong)(yong)(yong)扇形(xing)、半圓形(xing)和圓形(xing)。6kV以(yi)上交(jiao)聯(lian)電(dian)(dian)(dian)(dian)(dian)纜(lan)采(cai)(cai)用(yong)(yong)(yong)圓形(xing)緊(jin)壓(ya)(ya)(ya)(ya)線芯(xin)。油紙電(dian)(dian)(dian)(dian)(dian)纜(lan)均采(cai)(cai)用(yong)(yong)(yong)壓(ya)(ya)(ya)(ya)鉛機(ji)和壓(ya)(ya)(ya)(ya)鋁機(ji)擠包(bao)(bao)金(jin)屬套(tao)，35kv電(dian)(dian)(dian)(dian)(dian)力電(dian)(dian)(dian)(dian)(dian)纜(lan)，對(dui)于中低(di)壓(ya)(ya)(ya)(ya)交(jiao)聯(lian)電(dian)(dian)(dian)(dian)(dian)纜(lan)一般在有(you)化學腐蝕的(de)環境(jing)或水(shui)底敷(fu)設時才采(cai)(cai)用(yong)(yong)(yong)。但對(dui)于高壓(ya)(ya)(ya)(ya)電(dian)(dian)(dian)(dian)(dian)纜(lan)一般規(gui)定使(shi)用(yong)(yong)(yong)金(jin)屬護套(tao)。

絕(jue)緣(yuan)(yuan)(yuan)(yuan)層(ceng)(ceng)(ceng)的(de)(de)(de)(de)材(cai)(cai)料(liao)必須具(ju)有(you)(you)良好的(de)(de)(de)(de)電(dian)氣絕(jue)緣(yuan)(yuan)(yuan)(yuan)性(xing)(xing)能(neng)(neng)(neng)，主(zhu)要(yao)表現為(wei)(wei)承受電(dian)壓的(de)(de)(de)(de)大(da)小。一般地講，同(tong)一質(zhi)量的(de)(de)(de)(de)絕(jue)緣(yuan)(yuan)(yuan)(yuan)層(ceng)(ceng)(ceng)愈(yu)厚，耐(nai)電(dian)壓也越高(gao)。交聯聚(ju)乙(yi)烯(xi)具(ju)有(you)(you)優良的(de)(de)(de)(de)電(dian)氣絕(jue)緣(yuan)(yuan)(yuan)(yuan)性(xing)(xing)能(neng)(neng)(neng)，經過交聯后，它的(de)(de)(de)(de)耐(nai)熱和(he)機(ji)械性(xing)(xing)能(neng)(neng)(neng)大(da)幅(fu)度地提高(gao)，是目前理想的(de)(de)(de)(de)絕(jue)緣(yuan)(yuan)(yuan)(yuan)材(cai)(cai)料(liao)。導(dao)體包覆絕(jue)緣(yuan)(yuan)(yuan)(yuan)層(ceng)(ceng)(ceng)后稱(cheng)為(wei)(wei)絕(jue)緣(yuan)(yuan)(yuan)(yuan)線(xian)芯。每(mei)個導(dao)體上的(de)(de)(de)(de)絕(jue)緣(yuan)(yuan)(yuan)(yuan)層(ceng)(ceng)(ceng)，稱(cheng)為(wei)(wei)線(xian)芯的(de)(de)(de)(de)絕(jue)緣(yuan)(yuan)(yuan)(yuan)或(huo)簡稱(cheng)芯絕(jue)緣(yuan)(yuan)(yuan)(yuan)。成(cheng)品(pin)電(dian)壓試(shi)(shi)驗及絕(jue)緣(yuan)(yuan)(yuan)(yuan)線(xian)芯間電(dian)壓試(shi)(shi)驗不光要(yao)求(qiu)電(dian)纜有(you)(you)足夠的(de)(de)(de)(de)絕(jue)緣(yuan)(yuan)(yuan)(yuan)能(neng)(neng)(neng)力，還要(yao)求(qiu)絕(jue)緣(yuan)(yuan)(yuan)(yuan)或(huo)護套材(cai)(cai)料(liao)均(jun)勻無雜質(zhi)、厚度足夠均(jun)勻，表面(mian)不能(neng)(neng)(neng)有(you)(you)看不見的(de)(de)(de)(de)、等，否(fou)則(ze)就會造成(cheng)耐(nai)壓試(shi)(shi)驗時局部擊穿。

WDZN耐火(huo)(huo)電(dian)纜的(de)(de)主(zhu)要特(te)點是(shi)電(dian)纜除了能(neng)(neng)在正常的(de)(de)工(gong)作條件下(xia)傳輸電(dian)力外，電(dian)纜在著火(huo)(huo)燃(ran)燒(shao)時(shi)仍能(neng)(neng)保持一定(ding)時(shi)間的(de)(de)正常運行，適用(yong)于站、地(di)鐵、隧(sui)道、高層建筑等與防(fang)(fang)火(huo)(huo)安全和消防(fang)(fang)救生有(you)(you)關的(de)(de)地(di)方(fang)。引起電(dian)纜導體本身發熱，引起包(bao)覆導體的(de)(de)絕緣老化(hua)開裂，造(zao)成供電(dian)線路漏電(dian)、短路，甚至造(zao)成火(huo)(huo)災，危及人(ren)身、財產(chan)的(de)(de)安全。標準對不同(tong)規(gui)格電(dian)纜的(de)(de)導體直流電(dian)阻(zu)值(zhi)均有(you)(you)嚴格的(de)(de)規(gui)定(ding)，不得大(da)于標準規(gui)定(ding)的(de)(de)值(zhi)。交(jiao)聯(lian)絕緣的(de)(de)品種雖多，但主(zhu)要分為物理交(jiao)聯(lian)和化(hua)學交(jiao)聯(lian)兩大(da)類。物理交(jiao)聯(lian)也稱為輻(fu)照(zhao)交(jiao)聯(lian)，一般適用(yong)于絕緣厚(hou)度較薄的(de)(de)低壓電(dian)纜。化(hua)學交(jiao)聯(lian)方(fang)法比(bi)高能(neng)(neng)輻(fu)射交(jiao)聯(lian)工(gong)藝(yi)簡單(dan)，操作安全，輻(fu)照(zhao)交(jiao)聯(lian)聚乙烯的(de)(de)交(jiao)聯(lian)度約為70％，而化(hua)學交(jiao)聯(lian)可達70～90％。