国产精品成人网站/两攻一受3p双龙h调教/玩弄人妻少妇500系列/人妻换人妻仑乱/国产成人一区二区三区别

長途對稱通(tong)(tong)信電(dian)纜由不(bu)同數量和不(bu)同絕(jue)(jue)緣(yuan)結(jie)(jie)構(gou)(gou)的(de)四(si)線組構(gou)(gou)成。四(si)線組的(de)常用(yong)形(xing)式為星絞組，也有(you)的(de)采用(yong)復(fu)對絞形(xing)式（圖2）。絕(jue)(jue)緣(yuan)有(you)紙(zhi)(zhi)帶(dai)(dai)絕(jue)(jue)緣(yuan)、紙(zhi)(zhi)-繩（紙(zhi)(zhi)帶(dai)(dai)和紙(zhi)(zhi)繩）絕(jue)(jue)緣(yuan)、聚(ju)(ju)(ju)乙(yi)(yi)烯繩-帶(dai)(dai)絕(jue)(jue)緣(yuan)、聚(ju)(ju)(ju)苯(ben)乙(yi)(yi)烯繩－帶(dai)(dai)絕(jue)(jue)緣(yuan)和泡沫(mo)聚(ju)(ju)(ju)乙(yi)(yi)烯絕(jue)(jue)緣(yuan)等多種。高頻長途對稱通(tong)(tong)信電(dian)纜傳輸頻率高，所以對電(dian)纜的(de)結(jie)(jie)構(gou)(gou)性能(neng)要求較高。一般采用(yong)繩－帶(dai)(dai)絕(jue)(jue)緣(yuan)的(de)星絞四(si)線組結(jie)(jie)構(gou)(gou)。絕(jue)(jue)緣(yuan)材料常用(yong)聚(ju)(ju)(ju)苯(ben)乙(yi)(yi)烯、聚(ju)(ju)(ju)乙(yi)(yi)烯。紙(zhi)(zhi)帶(dai)(dai)紙(zhi)(zhi)繩絕(jue)(jue)緣(yuan)一般用(yong)于252千(qian)赫以下的(de)低頻對稱通(tong)(tong)信電(dian)纜。

電(dian)(dian)(dian)(dian)(dian)(dian)話電(dian)(dian)(dian)(dian)(dian)(dian)纜(lan)(lan)(lan)是用于市內(nei)、近(jin)郊和(he)工礦企業等較小(xiao)范圍的(de)區域電(dian)(dian)(dian)(dian)(dian)(dian)話連(lian)接的(de)對(dui)(dui)(dui)(dui)(dui)稱(cheng)通(tong)(tong)信電(dian)(dian)(dian)(dian)(dian)(dian)纜(lan)(lan)(lan)，常(chang)稱(cheng)市內(nei)電(dian)(dian)(dian)(dian)(dian)(dian)話電(dian)(dian)(dian)(dian)(dian)(dian)纜(lan)(lan)(lan)。其(qi)主要特點為(wei)(wei)(wei)對(dui)(dui)(dui)(dui)(dui)數多（最(zui)多可(ke)(ke)達數千(qian)對(dui)(dui)(dui)(dui)(dui)，一(yi)(yi)般為(wei)(wei)(wei)數百或數十(shi)對(dui)(dui)(dui)(dui)(dui)）。由(you)于使用頻(pin)率低，通(tong)(tong)信距離(li)近(jin)，因此線(xian)(xian)(xian)徑較長途通(tong)(tong)信電(dian)(dian)(dian)(dian)(dian)(dian)纜(lan)(lan)(lan)細，一(yi)(yi)般為(wei)(wei)(wei)0.5毫米(mi)。電(dian)(dian)(dian)(dian)(dian)(dian)話電(dian)(dian)(dian)(dian)(dian)(dian)纜(lan)(lan)(lan)的(de)線(xian)(xian)(xian)組結構有對(dui)(dui)(dui)(dui)(dui)絞(jiao)(jiao)組、星(xing)絞(jiao)(jiao)組和(he)復(fu)對(dui)(dui)(dui)(dui)(dui)絞(jiao)(jiao)組3種。按其(qi)線(xian)(xian)(xian)心絕(jue)(jue)緣(yuan)和(he)護層(ceng)材料(liao)可(ke)(ke)分為(wei)(wei)(wei)紙絕(jue)(jue)緣(yuan)鉛(qian)護套(tao)電(dian)(dian)(dian)(dian)(dian)(dian)纜(lan)(lan)(lan)、聚乙烯絕(jue)(jue)緣(yuan)組合(he)(he)護層(ceng)電(dian)(dian)(dian)(dian)(dian)(dian)纜(lan)(lan)(lan)、油(you)膏充填防水電(dian)(dian)(dian)(dian)(dian)(dian)纜(lan)(lan)(lan)、全塑電(dian)(dian)(dian)(dian)(dian)(dian)纜(lan)(lan)(lan)等。　電(dian)(dian)(dian)(dian)(dian)(dian)話電(dian)(dian)(dian)(dian)(dian)(dian)纜(lan)(lan)(lan)中(zhong)二根絕(jue)(jue)緣(yuan)導線(xian)(xian)(xian)心按一(yi)(yi)定節距絞(jiao)(jiao)合(he)(he)成(cheng)對(dui)(dui)(dui)(dui)(dui)構成(cheng)一(yi)(yi)個絕(jue)(jue)緣(yuan)線(xian)(xian)(xian)對(dui)(dui)(dui)(dui)(dui)。線(xian)(xian)(xian)對(dui)(dui)(dui)(dui)(dui)中(zhong)二根絕(jue)(jue)緣(yuan)導線(xian)(xian)(xian)心的(de)顏色不(bu)同（一(yi)(yi)般為(wei)(wei)(wei)紅(hong)色和(he)白色），以(yi)(yi)便接線(xian)(xian)(xian)時區分。電(dian)(dian)(dian)(dian)(dian)(dian)話電(dian)(dian)(dian)(dian)(dian)(dian)纜(lan)(lan)(lan)的(de)纜(lan)(lan)(lan)心結構一(yi)(yi)般分為(wei)(wei)(wei)同心式(shi)(shi)和(he)單位(wei)(wei)式(shi)(shi)兩種（圖3）。同一(yi)(yi)層(ceng)中(zhong)相(xiang)鄰線(xian)(xian)(xian)對(dui)(dui)(dui)(dui)(dui)的(de)絞(jiao)(jiao)合(he)(he)節距應不(bu)相(xiang)同，以(yi)(yi)減小(xiao)通(tong)(tong)話時的(de)相(xiang)互影響。在每一(yi)(yi)層(ceng)中(zhong)都設有一(yi)(yi)個標志對(dui)(dui)(dui)(dui)(dui)（分別為(wei)(wei)(wei)藍色和(he)白色），便于接線(xian)(xian)(xian)時辨認。在80對(dui)(dui)(dui)(dui)(dui)以(yi)(yi)上的(de)電(dian)(dian)(dian)(dian)(dian)(dian)纜(lan)(lan)(lan)中(zhong)往(wang)往(wang)置有預備(bei)線(xian)(xian)(xian)對(dui)(dui)(dui)(dui)(dui)以(yi)(yi)替(ti)換不(bu)合(he)(he)格線(xian)(xian)(xian)對(dui)(dui)(dui)(dui)(dui)。單位(wei)(wei)式(shi)(shi)電(dian)(dian)(dian)(dian)(dian)(dian)纜(lan)(lan)(lan)以(yi)(yi)50對(dui)(dui)(dui)(dui)(dui)或100對(dui)(dui)(dui)(dui)(dui)及(ji)相(xiang)應的(de)預備(bei)對(dui)(dui)(dui)(dui)(dui)絞(jiao)(jiao)合(he)(he)成(cheng)一(yi)(yi)個基(ji)本單位(wei)(wei)，再(zai)由(you)若干(gan)(gan)個基(ji)本單位(wei)(wei)絞(jiao)(jiao)合(he)(he)成(cheng)電(dian)(dian)(dian)(dian)(dian)(dian)纜(lan)(lan)(lan)心。經干(gan)(gan)燥(zao)后擠(ji)壓上護套(tao)制成(cheng)電(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(lan)(lan)需(xu)用自(zi)承(cheng)式(shi)，由鋼索承(cheng)受整(zheng)個電(dian)纜(lan)(lan)的(de)重力。20世紀60年代以(yi)來，研制出在塑料電(dian)纜(lan)(lan)中填充油(you)膏以(yi)防止潮氣和水分的(de)防水型(xing)電(dian)纜(lan)(lan)。

為了提高通信(xin)電(dian)纜(lan)(lan)(lan)的防潮性、穩定性，20世紀70年代以來，在市(shi)內電(dian)話電(dian)纜(lan)(lan)(lan)中廣泛采用綜(zong)合型(xing)電(dian)纜(lan)(lan)(lan)護(hu)層(ceng)(ceng)(ceng)。其基本類(lei)型(xing)有3種。①Alpeth：纜(lan)(lan)(lan)心外(wai)(wai)擠(ji)壓(ya)一(yi)層(ceng)(ceng)(ceng)聚(ju)(ju)乙烯護(hu)層(ceng)(ceng)(ceng)，再(zai)搭接地縱(zong)向包(bao)裹0.2毫米(mi)皺紋(wen)鋁帶，充以聚(ju)(ju)異(yi)丁烯絕緣復合物后外(wai)(wai)敷一(yi)層(ceng)(ceng)(ceng)熱塑性膠粘層(ceng)(ceng)(ceng)，最外(wai)(wai)面(mian)擠(ji)壓(ya)一(yi)層(ceng)(ceng)(ceng)聚(ju)(ju)乙烯護(hu)套。②Stalpeth：皺紋(wen)鋁帶外(wai)(wai)縱(zong)包(bao)一(yi)層(ceng)(ceng)(ceng)皺紋(wen)鋼(gang)帶，外(wai)(wai)覆(fu)一(yi)層(ceng)(ceng)(ceng)熱塑性材料(liao)(liao)，最外(wai)(wai)層(ceng)(ceng)(ceng)再(zai)擠(ji)壓(ya)一(yi)層(ceng)(ceng)(ceng)聚(ju)(ju)乙烯護(hu)套。③Lepeth：纜(lan)(lan)(lan)心上包(bao)覆(fu)一(yi)層(ceng)(ceng)(ceng)聚(ju)(ju)乙烯護(hu)套，其外(wai)(wai)敷一(yi)層(ceng)(ceng)(ceng)粘性熱塑性材料(liao)(liao)，最外(wai)(wai)面(mian)擠(ji)壓(ya)一(yi)層(ceng)(ceng)(ceng)鉛管。