擴(kuo)徑(jing)(jing)導(dao)線(xian)(xian)(xian)一般大多用在特(te)高壓線(xian)(xian)(xian)路(lu)、高海拔地(di)(di)區、人口(kou)密集的地(di)(di)區。按用途分(fen)為(wei)線(xian)(xian)(xian)路(lu)用和變(bian)電站(zhan)用兩(liang)大類；按結構特(te)點分(fen)為(wei)大內徑(jing)(jing)鋁(lv)管支(zhi)撐型(xing)(xing)擴(kuo)徑(jing)(jing)導(dao)線(xian)(xian)(xian)、小(xiao)內徑(jing)(jing)鋁(lv)管填充型(xing)(xing)擴(kuo)徑(jing)(jing)導(dao)線(xian)(xian)(xian)、疏絞型(xing)(xing)擴(kuo)徑(jing)(jing)導(dao)線(xian)(xian)(xian)、高密度(du)聚乙烯支(zhi)撐型(xing)(xing)擴(kuo)徑(jing)(jing)導(dao)線(xian)(xian)(xian)。

特高壓線路：特高壓輸(shu)電(dian)處于超大規模電(dian)力(li)輸(shu)送系統工程(cheng)中的高端，特高壓工程(cheng)以建設“環境友好型”工程(cheng)為目標，力(li)求全面優化工程(cheng)的設計方(fang)案，嚴格保(bao)證電(dian)場、磁場、可(ke)聽噪聲與無線電(dian)干擾水平滿足標準要求。

節約線(xian)(xian)路(lu)走廓用(yong)地(di)的措(cuo)施之一(yi)是(shi)輸(shu)(shu)(shu)電(dian)(dian)(dian)線(xian)(xian)路(lu)采用(yong)V型絕(jue)緣(yuan)子串，這樣可以減少拆遷、降低工(gong)(gong)(gong)程(cheng)造價，經濟利益顯(xian)著，但(dan)是(shi)V型絕(jue)緣(yuan)子串的采用(yong)將(jiang)使輸(shu)(shu)(shu)電(dian)(dian)(dian)線(xian)(xian)路(lu)的電(dian)(dian)(dian)磁環境變差。為此，若(ruo)輸(shu)(shu)(shu)電(dian)(dian)(dian)線(xian)(xian)路(lu)采用(yong)普(pu)通導(dao)(dao)線(xian)(xian)，則需要加大(da)導(dao)(dao)線(xian)(xian)截面(mian)(mian)和(he)增(zeng)加導(dao)(dao)線(xian)(xian)的分裂(lie)根數，這樣將(jiang)增(zeng)大(da)導(dao)(dao)線(xian)(xian)的使用(yong)量(liang)、鐵塔的結構尺(chi)寸和(he)重量(liang)等，從(cong)而(er)加大(da)工(gong)(gong)(gong)程(cheng)投資(zi)。如果(guo)在滿足(zu)輸(shu)(shu)(shu)電(dian)(dian)(dian)容量(liang)和(he)線(xian)(xian)路(lu)工(gong)(gong)(gong)程(cheng)要求(qiu)的前提下，設計(ji)一(yi)種保證輸(shu)(shu)(shu)電(dian)(dian)(dian)導(dao)(dao)體載(zai)流能(neng)力的新型結構導(dao)(dao)線(xian)(xian)，并將(jiang)直徑擴大(da)且(qie)盡(jin)可能(neng)使其表(biao)面(mian)(mian)光潔圓(yuan)滑，這樣就會(hui)大(da)大(da)節約導(dao)(dao)體材(cai)料，并且(qie)使導(dao)(dao)線(xian)(xian)的外徑與表(biao)面(mian)(mian)能(neng)滿足(zu)線(xian)(xian)路(lu)的輸(shu)(shu)(shu)電(dian)(dian)(dian)和(he)電(dian)(dian)(dian)暈要求(qiu)，從(cong)而(er)顯(xian)著降低線(xian)(xian)路(lu)投資(zi)。

采(cai)用(yong)適當(dang)的擴徑導(dao)線有利于降低特高壓(ya)工程(cheng)投資，而且可(ke)以減(jian)輕交流(liu)工程(cheng)所用(yong)導(dao)線的集膚效應(ying)，因此擴徑特別適用(yong)于交流(liu)特高壓(ya)工程(cheng)。