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長途對(dui)稱通信電纜(lan)由不同(tong)數量和不同(tong)絕(jue)(jue)緣(yuan)(yuan)結構的(de)四線組(zu)(zu)構成。四線組(zu)(zu)的(de)常用(yong)(yong)(yong)形式為(wei)星(xing)絞組(zu)(zu)，也有(you)(you)的(de)采(cai)用(yong)(yong)(yong)復對(dui)絞形式（圖2）。絕(jue)(jue)緣(yuan)(yuan)有(you)(you)紙帶(dai)絕(jue)(jue)緣(yuan)(yuan)、紙-繩(sheng)（紙帶(dai)和紙繩(sheng)）絕(jue)(jue)緣(yuan)(yuan)、聚(ju)(ju)乙烯(xi)繩(sheng)-帶(dai)絕(jue)(jue)緣(yuan)(yuan)、聚(ju)(ju)苯(ben)乙烯(xi)繩(sheng)－帶(dai)絕(jue)(jue)緣(yuan)(yuan)和泡沫聚(ju)(ju)乙烯(xi)絕(jue)(jue)緣(yuan)(yuan)等多(duo)種。高(gao)頻(pin)長途對(dui)稱通信電纜(lan)傳輸頻(pin)率高(gao)，所以對(dui)電纜(lan)的(de)結構性能要(yao)求(qiu)較高(gao)。一(yi)般采(cai)用(yong)(yong)(yong)繩(sheng)－帶(dai)絕(jue)(jue)緣(yuan)(yuan)的(de)星(xing)絞四線組(zu)(zu)結構。絕(jue)(jue)緣(yuan)(yuan)材料(liao)常用(yong)(yong)(yong)聚(ju)(ju)苯(ben)乙烯(xi)、聚(ju)(ju)乙烯(xi)。紙帶(dai)紙繩(sheng)絕(jue)(jue)緣(yuan)(yuan)一(yi)般用(yong)(yong)(yong)于252千赫以下的(de)低頻(pin)對(dui)稱通信電纜(lan)。

電(dian)(dian)(dian)(dian)(dian)(dian)(dian)話(hua)(hua)(hua)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)纜(lan)(lan)(lan)(lan)(lan)是(shi)用于市內(nei)、近(jin)郊和(he)工礦企業等較(jiao)小范圍(wei)的(de)(de)區域電(dian)(dian)(dian)(dian)(dian)(dian)(dian)話(hua)(hua)(hua)連接(jie)的(de)(de)對(dui)(dui)稱通信(xin)(xin)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)纜(lan)(lan)(lan)(lan)(lan)，常稱市內(nei)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)話(hua)(hua)(hua)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)纜(lan)(lan)(lan)(lan)(lan)。其(qi)主要特點為(wei)對(dui)(dui)數(shu)(shu)多(duo)（最多(duo)可達數(shu)(shu)千對(dui)(dui)，一(yi)(yi)(yi)般為(wei)數(shu)(shu)百或數(shu)(shu)十對(dui)(dui)）。由于使用頻率低(di)，通信(xin)(xin)距(ju)(ju)離近(jin)，因此線(xian)(xian)(xian)(xian)徑較(jiao)長途(tu)通信(xin)(xin)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)纜(lan)(lan)(lan)(lan)(lan)細，一(yi)(yi)(yi)般為(wei)0.5毫米(mi)。電(dian)(dian)(dian)(dian)(dian)(dian)(dian)話(hua)(hua)(hua)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)纜(lan)(lan)(lan)(lan)(lan)的(de)(de)線(xian)(xian)(xian)(xian)組結構有對(dui)(dui)絞(jiao)組、星絞(jiao)組和(he)復(fu)對(dui)(dui)絞(jiao)組3種。按其(qi)線(xian)(xian)(xian)(xian)心(xin)(xin)(xin)(xin)絕緣和(he)護(hu)層(ceng)(ceng)(ceng)材(cai)料可分為(wei)紙(zhi)絕緣鉛護(hu)套電(dian)(dian)(dian)(dian)(dian)(dian)(dian)纜(lan)(lan)(lan)(lan)(lan)、聚乙烯絕緣組合(he)護(hu)層(ceng)(ceng)(ceng)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)纜(lan)(lan)(lan)(lan)(lan)、油膏(gao)充填防水電(dian)(dian)(dian)(dian)(dian)(dian)(dian)纜(lan)(lan)(lan)(lan)(lan)、全塑電(dian)(dian)(dian)(dian)(dian)(dian)(dian)纜(lan)(lan)(lan)(lan)(lan)等。　電(dian)(dian)(dian)(dian)(dian)(dian)(dian)話(hua)(hua)(hua)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)纜(lan)(lan)(lan)(lan)(lan)中(zhong)二根絕緣導(dao)線(xian)(xian)(xian)(xian)心(xin)(xin)(xin)(xin)按一(yi)(yi)(yi)定節距(ju)(ju)絞(jiao)合(he)成(cheng)(cheng)對(dui)(dui)構成(cheng)(cheng)一(yi)(yi)(yi)個絕緣線(xian)(xian)(xian)(xian)對(dui)(dui)。線(xian)(xian)(xian)(xian)對(dui)(dui)中(zhong)二根絕緣導(dao)線(xian)(xian)(xian)(xian)心(xin)(xin)(xin)(xin)的(de)(de)顏色(se)不同(tong)(tong)（一(yi)(yi)(yi)般為(wei)紅(hong)色(se)和(he)白色(se)），以(yi)便接(jie)線(xian)(xian)(xian)(xian)時(shi)區分。電(dian)(dian)(dian)(dian)(dian)(dian)(dian)話(hua)(hua)(hua)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)纜(lan)(lan)(lan)(lan)(lan)的(de)(de)纜(lan)(lan)(lan)(lan)(lan)心(xin)(xin)(xin)(xin)結構一(yi)(yi)(yi)般分為(wei)同(tong)(tong)心(xin)(xin)(xin)(xin)式(shi)和(he)單位(wei)(wei)(wei)式(shi)兩種（圖(tu)3）。同(tong)(tong)一(yi)(yi)(yi)層(ceng)(ceng)(ceng)中(zhong)相(xiang)鄰線(xian)(xian)(xian)(xian)對(dui)(dui)的(de)(de)絞(jiao)合(he)節距(ju)(ju)應(ying)不相(xiang)同(tong)(tong)，以(yi)減(jian)小通話(hua)(hua)(hua)時(shi)的(de)(de)相(xiang)互影響。在每(mei)一(yi)(yi)(yi)層(ceng)(ceng)(ceng)中(zhong)都(dou)設有一(yi)(yi)(yi)個標(biao)志對(dui)(dui)（分別為(wei)藍色(se)和(he)白色(se)），便于接(jie)線(xian)(xian)(xian)(xian)時(shi)辨認。在80對(dui)(dui)以(yi)上的(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)纜(lan)(lan)(lan)(lan)(lan)中(zhong)往往置有預(yu)備線(xian)(xian)(xian)(xian)對(dui)(dui)以(yi)替換不合(he)格(ge)線(xian)(xian)(xian)(xian)對(dui)(dui)。單位(wei)(wei)(wei)式(shi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)纜(lan)(lan)(lan)(lan)(lan)以(yi)50對(dui)(dui)或100對(dui)(dui)及相(xiang)應(ying)的(de)(de)預(yu)備對(dui)(dui)絞(jiao)合(he)成(cheng)(cheng)一(yi)(yi)(yi)個基本單位(wei)(wei)(wei)，再由若干個基本單位(wei)(wei)(wei)絞(jiao)合(he)成(cheng)(cheng)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)纜(lan)(lan)(lan)(lan)(lan)心(xin)(xin)(xin)(xin)。經干燥后擠壓上護(hu)套制成(cheng)(cheng)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)纜(lan)(lan)(lan)(lan)(lan)（見圖(tu)）。

架空敷(fu)設的電(dian)(dian)話電(dian)(dian)纜(lan)需(xu)用自承式(shi)，由(you)鋼索承受整個電(dian)(dian)纜(lan)的重力。20世(shi)紀(ji)60年(nian)代以(yi)來，研(yan)制出(chu)在塑料(liao)電(dian)(dian)纜(lan)中填充油膏(gao)以(yi)防止潮氣和水(shui)分的防水(shui)型(xing)電(dian)(dian)纜(lan)。

為了提高通(tong)信電(dian)纜(lan)的防潮性(xing)(xing)、穩定性(xing)(xing)，20世紀70年代(dai)以(yi)來，在市內電(dian)話電(dian)纜(lan)中廣(guang)泛采(cai)用綜合型(xing)電(dian)纜(lan)護(hu)(hu)層(ceng)(ceng)(ceng)。其基(ji)本類型(xing)有(you)3種。①Alpeth：纜(lan)心外(wai)(wai)擠(ji)壓(ya)(ya)一(yi)(yi)(yi)(yi)層(ceng)(ceng)(ceng)聚(ju)乙(yi)(yi)烯(xi)護(hu)(hu)層(ceng)(ceng)(ceng)，再(zai)搭(da)接地縱向包(bao)(bao)裹0.2毫(hao)米皺紋鋁帶，充以(yi)聚(ju)異丁烯(xi)絕緣復合物后(hou)外(wai)(wai)敷一(yi)(yi)(yi)(yi)層(ceng)(ceng)(ceng)熱塑(su)性(xing)(xing)膠(jiao)粘層(ceng)(ceng)(ceng)，最外(wai)(wai)面擠(ji)壓(ya)(ya)一(yi)(yi)(yi)(yi)層(ceng)(ceng)(ceng)聚(ju)乙(yi)(yi)烯(xi)護(hu)(hu)套。②Stalpeth：皺紋鋁帶外(wai)(wai)縱包(bao)(bao)一(yi)(yi)(yi)(yi)層(ceng)(ceng)(ceng)皺紋鋼帶，外(wai)(wai)覆一(yi)(yi)(yi)(yi)層(ceng)(ceng)(ceng)熱塑(su)性(xing)(xing)材料，最外(wai)(wai)層(ceng)(ceng)(ceng)再(zai)擠(ji)壓(ya)(ya)一(yi)(yi)(yi)(yi)層(ceng)(ceng)(ceng)聚(ju)乙(yi)(yi)烯(xi)護(hu)(hu)套。③Lepeth：纜(lan)心上(shang)包(bao)(bao)覆一(yi)(yi)(yi)(yi)層(ceng)(ceng)(ceng)聚(ju)乙(yi)(yi)烯(xi)護(hu)(hu)套，其外(wai)(wai)敷一(yi)(yi)(yi)(yi)層(ceng)(ceng)(ceng)粘性(xing)(xing)熱塑(su)性(xing)(xing)材料，最外(wai)(wai)面擠(ji)壓(ya)(ya)一(yi)(yi)(yi)(yi)層(ceng)(ceng)(ceng)鉛管(guan)。