擴徑(jing)(jing)(jing)導(dao)(dao)(dao)線(xian)(xian)是以滿足(zu)技術條件的(de)(de)常(chang)規導(dao)(dao)(dao)線(xian)(xian)規格為基準，采(cai)取擴大(da)(da)導(dao)(dao)(dao)線(xian)(xian)外徑(jing)(jing)(jing)技術，在(zai)保證電(dian)暈(yun)所要求的(de)(de)導(dao)(dao)(dao)線(xian)(xian)外徑(jing)(jing)(jing)前提下，減少(shao)導(dao)(dao)(dao)線(xian)(xian)的(de)(de)鋁截面，從而減少(shao)導(dao)(dao)(dao)線(xian)(xian)的(de)(de)總重(zhong)量，減少(shao)鐵(tie)塔荷載(zai)和(he)(he)結構重(zhong)量，極大(da)(da)地(di)降(jiang)低線(xian)(xian)路造價。當線(xian)(xian)路的(de)(de)電(dian)壓超(chao)過(guo)220kv時，為了(le)降(jiang)低線(xian)(xian)路電(dian)抗和(he)(he)電(dian)暈(yun)損耗，通常(chang)采(cai)用(yong)擴徑(jing)(jing)(jing)導(dao)(dao)(dao)線(xian)(xian)。擴徑(jing)(jing)(jing)導(dao)(dao)(dao)線(xian)(xian)就(jiu)是把普通的(de)(de)導(dao)(dao)(dao)線(xian)(xian)做成(cheng)中空(kong)(kong)（里(li)面用(yong)多股鋼(gang)芯線(xian)(xian)和(he)(he)支撐層(ceng)做成(cheng)）或者減少(shao)其中部分層(ceng)單線(xian)(xian)數(shu)量（使該層(ceng)單線(xian)(xian)間存在(zai)一定(ding)數(shu)量空(kong)(kong)隙(xi)），最終達到(dao)增加導(dao)(dao)(dao)線(xian)(xian)的(de)(de)等效半徑(jing)(jing)(jing)的(de)(de)目的(de)(de)。擴徑(jing)(jing)(jing)導(dao)(dao)(dao)線(xian)(xian)在(zai)超(chao)高壓和(he)(he)特高壓輸電(dian)工程中有很大(da)(da)的(de)(de)應用(yong)空(kong)(kong)間，尤其在(zai)高海拔地(di)區有著(zhu)更(geng)為廣闊(kuo)的(de)(de)前景。

相對于常(chang)規(gui)導(dao)線(xian)(xian)，擴徑(jing)導(dao)線(xian)(xian)重量(liang)較輕，安裝敷設(she)后(hou)(hou)的 塑蠕伸長減小(xiao)，導(dao)線(xian)(xian)永(yong)久(jiu)變(bian)形減少(shao)，在滿足輸送容 量(liang)要(yao)求和環境保(bao)護指標的前提下(xia)，可大幅(fu)降(jiang)低線(xian)(xian)路 整體造價。簡單說來，擴徑(jing)導(dao)線(xian)(xian)是從常(chang)規(gui)導(dao)線(xian)(xian)中抽取(qu)數(shu)股鋁線(xian)(xian)后(hou)(hou)繞制而(er)成的，是常(chang)規(gui)導(dao)線(xian)(xian)時(shi)升(sheng)級進(jin)化品。

交流輸(shu)電(dian)線(xian)(xian)(xian)(xian)路的電(dian)暈損失主要與導(dao)線(xian)(xian)(xian)(xian)表面場 強和天氣有關，根據絕緣水平要求確定了(le)相間距(ju)離 后(hou)，導(dao)線(xian)(xian)(xian)(xian)表面場強主要與導(dao)線(xian)(xian)(xian)(xian)分裂(lie)數、分裂(lie)間距(ju)和 子(zi)導(dao)線(xian)(xian)(xian)(xian)直(zhi)(zhi)徑有關，分裂(lie)數越多，子(zi)導(dao)線(xian)(xian)(xian)(xian)直(zhi)(zhi)徑越大， 表面場強越小(xiao)。擴(kuo)徑導(dao)線(xian)(xian)(xian)(xian)通過支撐鋁線(xian)(xian)(xian)(xian)疏繞的方式 擴(kuo)大了(le)導(dao)線(xian)(xian)(xian)(xian)外徑，這樣可(ke)減小(xiao)導(dao)線(xian)(xian)(xian)(xian)表面的電(dian)場強度和電(dian)暈放電(dian)，降低噪聲(sheng)，減少對無線(xian)(xian)(xian)(xian)電(dian)的干(gan)擾。