擴(kuo)(kuo)徑(jing)(jing)導線(xian)(xian)(xian)是(shi)以滿足技(ji)術條(tiao)件(jian)的(de)常(chang)規(gui)(gui)導線(xian)(xian)(xian)規(gui)(gui)格為基(ji)準，采(cai)取擴(kuo)(kuo)大(da)導線(xian)(xian)(xian)外徑(jing)(jing)技(ji)術，在(zai)保證電(dian)(dian)暈所要求的(de)導線(xian)(xian)(xian)外徑(jing)(jing)前(qian)提(ti)下，減(jian)(jian)少(shao)(shao)導線(xian)(xian)(xian)的(de)鋁(lv)截面，從而減(jian)(jian)少(shao)(shao)導線(xian)(xian)(xian)的(de)總(zong)重量(liang)，減(jian)(jian)少(shao)(shao)鐵(tie)塔荷載(zai)和(he)結構重量(liang)，極大(da)地降低(di)線(xian)(xian)(xian)路造價。當線(xian)(xian)(xian)路的(de)電(dian)(dian)壓超過(guo)220kv時，為了(le)降低(di)線(xian)(xian)(xian)路電(dian)(dian)抗(kang)和(he)電(dian)(dian)暈損耗(hao)，通(tong)常(chang)采(cai)用擴(kuo)(kuo)徑(jing)(jing)導線(xian)(xian)(xian)。擴(kuo)(kuo)徑(jing)(jing)導線(xian)(xian)(xian)就是(shi)把普通(tong)的(de)導線(xian)(xian)(xian)做成(cheng)中(zhong)空（里面用多股鋼芯線(xian)(xian)(xian)和(he)支(zhi)撐層(ceng)做成(cheng)）或者減(jian)(jian)少(shao)(shao)其中(zhong)部分層(ceng)單線(xian)(xian)(xian)數量(liang)（使該(gai)層(ceng)單線(xian)(xian)(xian)間存在(zai)一定數量(liang)空隙），最終達到增加導線(xian)(xian)(xian)的(de)等效半徑(jing)(jing)的(de)目的(de)。擴(kuo)(kuo)徑(jing)(jing)導線(xian)(xian)(xian)在(zai)超高壓和(he)特高壓輸電(dian)(dian)工程中(zhong)有很大(da)的(de)應用空間，尤其在(zai)高海拔地區有著(zhu)更(geng)為廣闊的(de)前(qian)景。

相對于常規(gui)導(dao)線(xian)，擴徑導(dao)線(xian)重量較輕，安裝(zhuang)敷設(she)后的 塑蠕伸長減小，導(dao)線(xian)永久變形減少，在滿(man)足輸送容 量要(yao)求和環境保護(hu)指標的前提下(xia)，可大幅(fu)降低線(xian)路(lu) 整體造價。簡單說來，擴徑導(dao)線(xian)是從(cong)常規(gui)導(dao)線(xian)中抽取(qu)數股鋁線(xian)后繞制而(er)成的，是常規(gui)導(dao)線(xian)時升級進化品。

交流輸電(dian)線(xian)(xian)路(lu)的(de)電(dian)暈損失(shi)主要(yao)(yao)與(yu)導(dao)線(xian)(xian)表(biao)(biao)面場 強(qiang)(qiang)和天氣有關，根據絕緣水平要(yao)(yao)求(qiu)確定了相(xiang)間(jian)(jian)距離(li) 后，導(dao)線(xian)(xian)表(biao)(biao)面場強(qiang)(qiang)主要(yao)(yao)與(yu)導(dao)線(xian)(xian)分裂(lie)(lie)(lie)數、分裂(lie)(lie)(lie)間(jian)(jian)距和 子(zi)導(dao)線(xian)(xian)直徑(jing)有關，分裂(lie)(lie)(lie)數越多，子(zi)導(dao)線(xian)(xian)直徑(jing)越大(da)(da)， 表(biao)(biao)面場強(qiang)(qiang)越小(xiao)。擴徑(jing)導(dao)線(xian)(xian)通過(guo)支撐鋁線(xian)(xian)疏繞(rao)的(de)方式 擴大(da)(da)了導(dao)線(xian)(xian)外徑(jing)，這樣(yang)可(ke)減(jian)小(xiao)導(dao)線(xian)(xian)表(biao)(biao)面的(de)電(dian)場強(qiang)(qiang)度和電(dian)暈放電(dian)，降低噪聲，減(jian)少對(dui)無(wu)線(xian)(xian)電(dian)的(de)干擾(rao)。