在(zai)導(dao)體上、絕(jue)(jue)緣(yuan)(yuan)(yuan)層上、電(dian)(dian)(dian)纜芯上或(huo)(huo)電(dian)(dian)(dian)線電(dian)(dian)(dian)纜外層，為(wei)了(le)防止外界電(dian)(dian)(dian)磁波干(gan)擾或(huo)(huo)是(shi)起(qi)均勻(yun)電(dian)(dian)(dian)埸(yi)作(zuo)用(yong)，還包有(you)金屬帶、絲(si)或(huo)(huo)半導(dao)電(dian)(dian)(dian)塑料(liao)等(deng)材(cai)(cai)料(liao)。這些(xie)都稱(cheng)為(wei)屏(ping)蔽層。電(dian)(dian)(dian)纜通(tong)電(dian)(dian)(dian)以(yi)后，導(dao)體要(yao)發熱。因此，比較理想的絕(jue)(jue)緣(yuan)(yuan)(yuan)材(cai)(cai)料(liao)，應有(you)良(liang)好(hao)(hao)的絕(jue)(jue)緣(yuan)(yuan)(yuan)性(xing)(xing)能(neng)，和(he)(he)良(liang)好(hao)(hao)的熱傳導(dao)性(xing)(xing)能(neng)。絕(jue)(jue)緣(yuan)(yuan)(yuan)在(zai)電(dian)(dian)(dian)和(he)(he)熱的作(zuo)用(yong)下，內部會產生變化(hua)，天長日久(jiu)，絕(jue)(jue)緣(yuan)(yuan)(yuan)性(xing)(xing)能(neng)就(jiu)要(yao)降低。絕(jue)(jue)緣(yuan)(yuan)(yuan)電(dian)(dian)(dian)阻、成品(pin)電(dian)(dian)(dian)壓試驗及絕(jue)(jue)緣(yuan)(yuan)(yuan)線芯間電(dian)(dian)(dian)壓試驗，電(dian)(dian)(dian)力電(dian)(dian)(dian)纜廠，均考查的是(shi)電(dian)(dian)(dian)纜絕(jue)(jue)緣(yuan)(yuan)(yuan)層和(he)(he)護套層的電(dian)(dian)(dian)氣絕(jue)(jue)緣(yuan)(yuan)(yuan)性(xing)(xing)能(neng)，絕(jue)(jue)緣(yuan)(yuan)(yuan)電(dian)(dian)(dian)阻是(shi)檢測(ce)兩個導(dao)體之(zhi)間絕(jue)(jue)緣(yuan)(yuan)(yuan)材(cai)(cai)料(liao)的電(dian)(dian)(dian)阻，它應足夠大(da)以(yi)起(qi)到(dao)絕(jue)(jue)緣(yuan)(yuan)(yuan)保(bao)護作(zuo)用(yong)。

中高壓電(dian)纜一(yi)(yi)(yi)般采用過氧化(hua)(hua)物交聯(lian)，即用化(hua)(hua)學方法將線(xian)(xian)性分(fen)子(zi)通過化(hua)(hua)學交聯(lian)反(fan)應(ying)起來，轉化(hua)(hua)為立體網狀結(jie)構(gou)。化(hua)(hua)學交聯(lian)一(yi)(yi)(yi)般還(huan)可(ke)分(fen)為過氧化(hua)(hua)物交聯(lian)和(he)(he)接枝交聯(lian)兩種(zhong)。每層(ceng)單線(xian)(xian)的(de)(de)(de)絞合方向(xiang)應(ying)和(he)(he)前一(yi)(yi)(yi)層(ceng)方向(xiang)相反(fan)，外層(ceng)應(ying)用左向(xiang)絞合。這(zhe)種(zhong)結(jie)構(gou)可(ke)保(bao)證電(dian)纜導(dao)電(dian)線(xian)(xian)芯的(de)(de)(de)穩定(ding)性和(he)(he)一(yi)(yi)(yi)定(ding)的(de)(de)(de)柔(rou)軟性。絕(jue)(jue)緣層(ceng)的(de)(de)(de)材料必(bi)須(xu)具有良好的(de)(de)(de)電(dian)氣(qi)絕(jue)(jue)緣性能(neng)，主要(yao)表(biao)現(xian)為承受電(dian)壓的(de)(de)(de)大小(xiao)。一(yi)(yi)(yi)般地講，同(tong)一(yi)(yi)(yi)質(zhi)量的(de)(de)(de)絕(jue)(jue)緣層(ceng)愈厚，耐電(dian)壓也越高。

在導(dao)體上、絕緣層(ceng)(ceng)上、電(dian)(dian)纜(lan)芯上或電(dian)(dian)線(xian)電(dian)(dian)纜(lan)外層(ceng)(ceng)，為了防(fang)止外界電(dian)(dian)磁(ci)波干擾或是起均勻電(dian)(dian)埸作(zuo)用，還包(bao)有金屬帶(dai)、絲或半(ban)導(dao)電(dian)(dian)塑料等材料。這些都稱(cheng)為屏蔽層(ceng)(ceng)。WDZN耐(nai)火電(dian)(dian)纜(lan)的主要(yao)特點是電(dian)(dian)纜(lan)除了能在正(zheng)常的工作(zuo)條件下傳輸電(dian)(dian)力外，電(dian)(dian)纜(lan)在著火燃燒時(shi)仍(reng)能保持一定時(shi)間的正(zheng)常運行，適(shi)用于站、地鐵(tie)、隧道、高層(ceng)(ceng)建筑等與(yu)防(fang)火安全和消防(fang)救(jiu)生有關的地方。每層(ceng)(ceng)單線(xian)的絞(jiao)合方向應和前一層(ceng)(ceng)方向相反(fan)，外層(ceng)(ceng)應用左(zuo)向絞(jiao)合。這種結構可保證電(dian)(dian)纜(lan)導(dao)電(dian)(dian)線(xian)芯的穩定性和一定的柔軟性。