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長途對(dui)(dui)稱(cheng)通(tong)(tong)信電(dian)纜由不同數量和(he)不同絕(jue)(jue)(jue)(jue)緣(yuan)(yuan)(yuan)結構(gou)(gou)的(de)(de)四(si)線(xian)組構(gou)(gou)成。四(si)線(xian)組的(de)(de)常(chang)用(yong)形(xing)式為星絞(jiao)組，也有(you)的(de)(de)采用(yong)復對(dui)(dui)絞(jiao)形(xing)式（圖2）。絕(jue)(jue)(jue)(jue)緣(yuan)(yuan)(yuan)有(you)紙(zhi)(zhi)(zhi)(zhi)帶絕(jue)(jue)(jue)(jue)緣(yuan)(yuan)(yuan)、紙(zhi)(zhi)(zhi)(zhi)-繩(sheng)(sheng)（紙(zhi)(zhi)(zhi)(zhi)帶和(he)紙(zhi)(zhi)(zhi)(zhi)繩(sheng)(sheng)）絕(jue)(jue)(jue)(jue)緣(yuan)(yuan)(yuan)、聚乙(yi)烯繩(sheng)(sheng)-帶絕(jue)(jue)(jue)(jue)緣(yuan)(yuan)(yuan)、聚苯乙(yi)烯繩(sheng)(sheng)－帶絕(jue)(jue)(jue)(jue)緣(yuan)(yuan)(yuan)和(he)泡(pao)沫(mo)聚乙(yi)烯絕(jue)(jue)(jue)(jue)緣(yuan)(yuan)(yuan)等多種。高頻(pin)長途對(dui)(dui)稱(cheng)通(tong)(tong)信電(dian)纜傳輸頻(pin)率高，所以對(dui)(dui)電(dian)纜的(de)(de)結構(gou)(gou)性能要(yao)求較高。一(yi)般采用(yong)繩(sheng)(sheng)－帶絕(jue)(jue)(jue)(jue)緣(yuan)(yuan)(yuan)的(de)(de)星絞(jiao)四(si)線(xian)組結構(gou)(gou)。絕(jue)(jue)(jue)(jue)緣(yuan)(yuan)(yuan)材料(liao)常(chang)用(yong)聚苯乙(yi)烯、聚乙(yi)烯。紙(zhi)(zhi)(zhi)(zhi)帶紙(zhi)(zhi)(zhi)(zhi)繩(sheng)(sheng)絕(jue)(jue)(jue)(jue)緣(yuan)(yuan)(yuan)一(yi)般用(yong)于252千赫以下(xia)的(de)(de)低頻(pin)對(dui)(dui)稱(cheng)通(tong)(tong)信電(dian)纜。

電(dian)(dian)(dian)(dian)(dian)(dian)(dian)話(hua)(hua)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)纜(lan)(lan)(lan)是用于(yu)市內、近(jin)(jin)郊(jiao)和(he)(he)工(gong)礦企業等較小范圍(wei)的(de)(de)區域電(dian)(dian)(dian)(dian)(dian)(dian)(dian)話(hua)(hua)連接的(de)(de)對(dui)(dui)(dui)(dui)稱(cheng)通(tong)信(xin)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)纜(lan)(lan)(lan)，常稱(cheng)市內電(dian)(dian)(dian)(dian)(dian)(dian)(dian)話(hua)(hua)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)纜(lan)(lan)(lan)。其主要特點(dian)為(wei)(wei)對(dui)(dui)(dui)(dui)數多（最(zui)多可(ke)達數千對(dui)(dui)(dui)(dui)，一(yi)般為(wei)(wei)數百或(huo)數十對(dui)(dui)(dui)(dui)）。由(you)(you)于(yu)使用頻率低(di)，通(tong)信(xin)距(ju)離(li)近(jin)(jin)，因(yin)此(ci)線(xian)徑較長途通(tong)信(xin)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)纜(lan)(lan)(lan)細，一(yi)般為(wei)(wei)0.5毫米(mi)。電(dian)(dian)(dian)(dian)(dian)(dian)(dian)話(hua)(hua)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)纜(lan)(lan)(lan)的(de)(de)線(xian)組(zu)結構(gou)有(you)對(dui)(dui)(dui)(dui)絞(jiao)(jiao)(jiao)組(zu)、星絞(jiao)(jiao)(jiao)組(zu)和(he)(he)復對(dui)(dui)(dui)(dui)絞(jiao)(jiao)(jiao)組(zu)3種(zhong)(zhong)。按(an)其線(xian)心絕(jue)緣(yuan)和(he)(he)護(hu)層(ceng)材料可(ke)分(fen)為(wei)(wei)紙絕(jue)緣(yuan)鉛護(hu)套(tao)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)纜(lan)(lan)(lan)、聚乙烯絕(jue)緣(yuan)組(zu)合(he)(he)護(hu)層(ceng)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)纜(lan)(lan)(lan)、油(you)膏充填防水(shui)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)纜(lan)(lan)(lan)、全塑電(dian)(dian)(dian)(dian)(dian)(dian)(dian)纜(lan)(lan)(lan)等。　電(dian)(dian)(dian)(dian)(dian)(dian)(dian)話(hua)(hua)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)纜(lan)(lan)(lan)中(zhong)二根絕(jue)緣(yuan)導(dao)線(xian)心按(an)一(yi)定節距(ju)絞(jiao)(jiao)(jiao)合(he)(he)成(cheng)對(dui)(dui)(dui)(dui)構(gou)成(cheng)一(yi)個(ge)絕(jue)緣(yuan)線(xian)對(dui)(dui)(dui)(dui)。線(xian)對(dui)(dui)(dui)(dui)中(zhong)二根絕(jue)緣(yuan)導(dao)線(xian)心的(de)(de)顏色(se)不同（一(yi)般為(wei)(wei)紅色(se)和(he)(he)白(bai)色(se)），以(yi)(yi)便(bian)接線(xian)時(shi)區分(fen)。電(dian)(dian)(dian)(dian)(dian)(dian)(dian)話(hua)(hua)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)纜(lan)(lan)(lan)的(de)(de)纜(lan)(lan)(lan)心結構(gou)一(yi)般分(fen)為(wei)(wei)同心式和(he)(he)單(dan)位式兩種(zhong)(zhong)（圖3）。同一(yi)層(ceng)中(zhong)相(xiang)(xiang)鄰(lin)線(xian)對(dui)(dui)(dui)(dui)的(de)(de)絞(jiao)(jiao)(jiao)合(he)(he)節距(ju)應(ying)不相(xiang)(xiang)同，以(yi)(yi)減小通(tong)話(hua)(hua)時(shi)的(de)(de)相(xiang)(xiang)互影響(xiang)。在每一(yi)層(ceng)中(zhong)都設有(you)一(yi)個(ge)標志對(dui)(dui)(dui)(dui)（分(fen)別為(wei)(wei)藍(lan)色(se)和(he)(he)白(bai)色(se)），便(bian)于(yu)接線(xian)時(shi)辨認(ren)。在80對(dui)(dui)(dui)(dui)以(yi)(yi)上的(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)纜(lan)(lan)(lan)中(zhong)往往置(zhi)有(you)預備線(xian)對(dui)(dui)(dui)(dui)以(yi)(yi)替換不合(he)(he)格線(xian)對(dui)(dui)(dui)(dui)。單(dan)位式電(dian)(dian)(dian)(dian)(dian)(dian)(dian)纜(lan)(lan)(lan)以(yi)(yi)50對(dui)(dui)(dui)(dui)或(huo)100對(dui)(dui)(dui)(dui)及相(xiang)(xiang)應(ying)的(de)(de)預備對(dui)(dui)(dui)(dui)絞(jiao)(jiao)(jiao)合(he)(he)成(cheng)一(yi)個(ge)基本(ben)(ben)單(dan)位，再由(you)(you)若干個(ge)基本(ben)(ben)單(dan)位絞(jiao)(jiao)(jiao)合(he)(he)成(cheng)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)纜(lan)(lan)(lan)心。經干燥(zao)后擠(ji)壓上護(hu)套(tao)制成(cheng)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)纜(lan)(lan)(lan)（見圖）。

架(jia)空敷設的(de)電(dian)話電(dian)纜需用自承式，由鋼索承受整個電(dian)纜的(de)重力。20世紀60年代以來，研制出在塑料電(dian)纜中填充(chong)油膏以防止(zhi)潮氣(qi)和(he)水(shui)分的(de)防水(shui)型電(dian)纜。

為了提高通(tong)信電(dian)(dian)纜(lan)的防潮性(xing)(xing)、穩定性(xing)(xing)，20世(shi)紀70年代以(yi)來，在市內電(dian)(dian)話(hua)電(dian)(dian)纜(lan)中廣泛采用綜合型電(dian)(dian)纜(lan)護(hu)(hu)層(ceng)(ceng)。其基本類型有3種。①Alpeth：纜(lan)心(xin)外(wai)(wai)擠壓一(yi)層(ceng)(ceng)聚(ju)乙(yi)烯護(hu)(hu)層(ceng)(ceng)，再(zai)搭接地縱向包(bao)裹0.2毫米(mi)皺(zhou)紋(wen)(wen)鋁帶(dai)，充以(yi)聚(ju)異(yi)丁烯絕緣(yuan)復合物(wu)后(hou)外(wai)(wai)敷一(yi)層(ceng)(ceng)熱塑性(xing)(xing)膠粘(zhan)層(ceng)(ceng)，最外(wai)(wai)面擠壓一(yi)層(ceng)(ceng)聚(ju)乙(yi)烯護(hu)(hu)套。②Stalpeth：皺(zhou)紋(wen)(wen)鋁帶(dai)外(wai)(wai)縱包(bao)一(yi)層(ceng)(ceng)皺(zhou)紋(wen)(wen)鋼帶(dai)，外(wai)(wai)覆一(yi)層(ceng)(ceng)熱塑性(xing)(xing)材料，最外(wai)(wai)層(ceng)(ceng)再(zai)擠壓一(yi)層(ceng)(ceng)聚(ju)乙(yi)烯護(hu)(hu)套。③Lepeth：纜(lan)心(xin)上包(bao)覆一(yi)層(ceng)(ceng)聚(ju)乙(yi)烯護(hu)(hu)套，其外(wai)(wai)敷一(yi)層(ceng)(ceng)粘(zhan)性(xing)(xing)熱塑性(xing)(xing)材料，最外(wai)(wai)面擠壓一(yi)層(ceng)(ceng)鉛(qian)管。