擴(kuo)徑(jing)導(dao)線(xian)(xian)(xian)是以滿足(zu)技術條件(jian)的(de)常規導(dao)線(xian)(xian)(xian)規格為基準，采取擴(kuo)大導(dao)線(xian)(xian)(xian)外徑(jing)技術，在保證電暈所要求(qiu)的(de)導(dao)線(xian)(xian)(xian)外徑(jing)前(qian)提下，減少導(dao)線(xian)(xian)(xian)的(de)鋁截面，從而減少導(dao)線(xian)(xian)(xian)的(de)總(zong)重量，減少鐵(tie)塔荷載和結構重量，極大地降低線(xian)(xian)(xian)路(lu)造價。

當線(xian)路(lu)的(de)電(dian)壓超(chao)過220kv時，為了降低(di)線(xian)路(lu)電(dian)抗和電(dian)暈損耗，通常(chang)采用(yong)擴(kuo)徑(jing)導(dao)(dao)線(xian)。擴(kuo)徑(jing)導(dao)(dao)線(xian)就(jiu)是(shi)把普通的(de)導(dao)(dao)線(xian)做成中空（里面用(yong)多股芯線(xian)和支撐層做成）或者減少其中部分層單線(xian)數量(liang)（使該層單線(xian)間(jian)存在(zai)一(yi)定數量(liang)空隙），最(zui)終(zhong)達到增加導(dao)(dao)線(xian)的(de)等效半徑(jing)的(de)目的(de)。

交(jiao)流輸電(dian)線(xian)(xian)(xian)(xian)路的(de)電(dian)暈損失主(zhu)要與導(dao)(dao)(dao)(dao)線(xian)(xian)(xian)(xian)表(biao)面(mian)場強(qiang)和(he)天氣有關，根據絕(jue)緣水平要求確定了(le)相(xiang)間(jian)距離后(hou)(hou)，導(dao)(dao)(dao)(dao)線(xian)(xian)(xian)(xian)表(biao)面(mian)場強(qiang)主(zhu)要與導(dao)(dao)(dao)(dao)線(xian)(xian)(xian)(xian)分(fen)(fen)裂數(shu)、分(fen)(fen)裂間(jian)距和(he) 子導(dao)(dao)(dao)(dao)線(xian)(xian)(xian)(xian)直徑(jing)有關，分(fen)(fen)裂數(shu)越多，子導(dao)(dao)(dao)(dao)線(xian)(xian)(xian)(xian)直徑(jing)越大(da)， 表(biao)面(mian)場強(qiang)越小。擴(kuo)(kuo)徑(jing)導(dao)(dao)(dao)(dao)線(xian)(xian)(xian)(xian)通過支撐(cheng)鋁線(xian)(xian)(xian)(xian)疏(shu)繞(rao)的(de)方式(shi) 擴(kuo)(kuo)大(da)了(le)導(dao)(dao)(dao)(dao)線(xian)(xian)(xian)(xian)外徑(jing)，這樣可(ke)(ke)減(jian)小導(dao)(dao)(dao)(dao)線(xian)(xian)(xian)(xian)表(biao)面(mian)的(de)電(dian)場強(qiang)度(du)和(he)電(dian)暈放電(dian)，降低噪聲，減(jian)少(shao)對(dui)無線(xian)(xian)(xian)(xian)電(dian)的(de)干擾。相(xiang) 對(dui)于常規導(dao)(dao)(dao)(dao)線(xian)(xian)(xian)(xian)，擴(kuo)(kuo)徑(jing)導(dao)(dao)(dao)(dao)線(xian)(xian)(xian)(xian)重量較輕(qing)，安裝敷設后(hou)(hou)的(de) 塑蠕伸長(chang)減(jian)小，導(dao)(dao)(dao)(dao)線(xian)(xian)(xian)(xian)永久變形減(jian)少(shao)，在滿足輸送容 量要求和(he)環(huan)境保護指標的(de)前提下(xia)，可(ke)(ke)大(da)幅降低線(xian)(xian)(xian)(xian)路 整體(ti)造價(jia)。簡單說來，擴(kuo)(kuo)徑(jing)導(dao)(dao)(dao)(dao)線(xian)(xian)(xian)(xian)是從常規導(dao)(dao)(dao)(dao)線(xian)(xian)(xian)(xian)中抽取數(shu)股 鋁線(xian)(xian)(xian)(xian)后(hou)(hou)繞(rao)制而成的(de)，是常規導(dao)(dao)(dao)(dao)線(xian)(xian)(xian)(xian)時升級進化品。