一、工作(zuo)原理簡(jian)介
BYST-230A電纜識別儀是用于將某一特定(ding)電(dian)纜從(cong)一束電(dian)纜中識別出來的專用儀器。
BYST-230A電纜識別儀是一小型化手提式(shi)，緊湊型儀器(qi)，裝(zhuang)在鋁合金(jin)箱(xiang)內(nei)，由一個信號發生(sheng)器(qi)，一個帶卡鉗的(de)接收機(ji)及連線構成。
為(wei)了(le)可靠(kao)準確(que)地識(shi)別電纜，需要給被(bei)識(shi)別電纜加一特殊的(de)信號，該信號要被(bei)專用(yong)接收(shou)機接收(shou)，利用(yong)這一特性便能識(shi)別出(chu)要找的(de)電纜。
該儀器按下述原理(li)工作：
發生器將周(zhou)期性(xing)(xing)的(de)單極(ji)性(xing)(xing)電(dian)(dian)(dian)(dian)(dian)(dian)壓脈沖饋(kui)(kui)入要識別(bie)的(de)電(dian)(dian)(dian)(dian)(dian)(dian)纜(lan)中(zhong)，該電(dian)(dian)(dian)(dian)(dian)(dian)纜(lan)需要在(zai)遠端接(jie)地，以(yi)保證(zheng)有足夠大(da)的(de)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)流(liu)(liu)(liu)(liu)過電(dian)(dian)(dian)(dian)(dian)(dian)纜(lan)。該系統要設(she)計成返(fan)(fan)(fan)回電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)不要從(cong)同一(yi)(yi)電(dian)(dian)(dian)(dian)(dian)(dian)纜(lan)中(zhong)返(fan)(fan)(fan)回，能做(zuo)到(dao)這(zhe)(zhe)一(yi)(yi)點，饋(kui)(kui)入電(dian)(dian)(dian)(dian)(dian)(dian)纜(lan)中(zhong)的(de)脈沖電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)的(de)方向可(ke)做(zuo)為一(yi)(yi)明顯(xian)的(de)識別(bie)標準，流(liu)(liu)(liu)(liu)出(chu)去的(de)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)僅從(cong)這(zhe)(zhe)一(yi)(yi)根電(dian)(dian)(dian)(dian)(dian)(dian)纜(lan)通過，所有其它鄰近電(dian)(dian)(dian)(dian)(dian)(dian)纜(lan)中(zhong)流(liu)(liu)(liu)(liu)過的(de)都是返(fan)(fan)(fan)回電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)，但它們的(de)極(ji)性(xing)(xing)相(xiang)反。除了(le)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)方向這(zhe)(zhe)一(yi)(yi)實際(ji)差異外，電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)幅度也是一(yi)(yi)識別(bie)特征，流(liu)(liu)(liu)(liu)出(chu)去的(de)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)僅通過一(yi)(yi)根電(dian)(dian)(dian)(dian)(dian)(dian)纜(lan)、而(er)返(fan)(fan)(fan)回電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)可(ke)通過幾根電(dian)(dian)(dian)(dian)(dian)(dian)纜(lan)、這(zhe)(zhe)意味著(zhu)流(liu)(liu)(liu)(liu)出(chu)去的(de)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)比流(liu)(liu)(liu)(liu)過其它電(dian)(dian)(dian)(dian)(dian)(dian)纜(lan)的(de)返(fan)(fan)(fan)回電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)大(da)。
接(jie)收機的(de)(de)任務是(shi)探測(ce)流(liu)(liu)(liu)(liu)過(guo)電(dian)(dian)(dian)(dian)(dian)(dian)纜電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)方(fang)向(xiang)(xiang)(xiang)以及它的(de)(de)大(da)小。為(wei)達到(dao)這(zhe)一目的(de)(de)，電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)卡(ka)鉗(qian)(qian)被(bei)用作傳感器(qi)，它帶(dai)有(you)一放(fang)大(da)器(qi)并(bing)串(chuan)聯在(zai)電(dian)(dian)(dian)(dian)(dian)(dian)路中(zhong)(zhong)，卡(ka)鉗(qian)(qian)鉗(qian)(qian)住被(bei)測(ce)電(dian)(dian)(dian)(dian)(dian)(dian)纜，電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)流(liu)(liu)(liu)(liu)過(guo)電(dian)(dian)(dian)(dian)(dian)(dian)纜產生(sheng)的(de)(de)磁場(chang)在(zai)卡(ka)鉗(qian)(qian)的(de)(de)線(xian)(xian)圈中(zhong)(zhong)感應出(chu)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)，該電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)極(ji)(ji)性由電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)方(fang)向(xiang)(xiang)(xiang)和卡(ka)鉗(qian)(qian)線(xian)(xian)圈的(de)(de)方(fang)向(xiang)(xiang)(xiang)決定(ding)。為(wei)了得到(dao)明顯(xian)有(you)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)方(fang)向(xiang)(xiang)(xiang)的(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)極(ji)(ji)性，對一束電(dian)(dian)(dian)(dian)(dian)(dian)纜中(zhong)(zhong)所有(you)電(dian)(dian)(dian)(dian)(dian)(dian)纜進行測(ce)試都采取相同正(zheng)確的(de)(de)繞組方(fang)向(xiang)(xiang)(xiang)，這(zhe)就(jiu)是(shi)卡(ka)鉗(qian)(qian)上標有(you)箭(jian)頭的(de)(de)原(yuan)因。卡(ka)鉗(qian)(qian)上箭(jian)頭的(de)(de)方(fang)向(xiang)(xiang)(xiang)應指(zhi)向(xiang)(xiang)(xiang)電(dian)(dian)(dian)(dian)(dian)(dian)纜遠端(duan)，卡(ka)鉗(qian)(qian)線(xian)(xian)圈中(zhong)(zhong)感應的(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)在(zai)表頭中(zhong)(zhong)顯(xian)示(shi)出(chu)來，如果(guo)卡(ka)鉗(qian)(qian)按上述方(fang)式連接(jie)，指(zhi)針擺動方(fang)向(xiang)(xiang)(xiang)可顯(xian)示(shi)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)方(fang)向(xiang)(xiang)(xiang)，即只有(you)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)流(liu)(liu)(liu)(liu)出(chu)的(de)(de)這(zhe)根電(dian)(dian)(dian)(dian)(dian)(dian)纜指(zhi)針向(xiang)(xiang)(xiang)右(you)偏(pian)，這(zhe)根就(jiu)是(shi)要找的(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)纜。所有(you)其它電(dian)(dian)(dian)(dian)(dian)(dian)纜只流(liu)(liu)(liu)(liu)過(guo)返回(hui)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)，指(zhi)針向(xiang)(xiang)(xiang)左(zuo)偏(pian)、或無(wu)脈動電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)，指(zhi)針不偏(pian)轉(zhuan)。接(jie)收機上的(de)(de)放(fang)大(da)調節(jie)器(qi)可調整信號(hao)強度(du)。
二、BYST-230A電纜(lan)識別(bie)儀外型(xing)及功能介紹
識別儀(yi)主(zhu)機及(ji)接收機外(wai)型如圖1所示
圖1 識別(bie)儀(yi)外(wai)型及功能圖
主機(ji)外型尺寸：400mm×270mm×210mm
接收機(ji)外型(xing)尺寸：155mm×205mm×50mm
識別儀主機各部分功能如(ru)下：
1.電(dian)源開關：控制整機電(dian)源通(tong)斷。
2.電(dian)(dian)(dian)源(yuan)輸(shu)入插座(zuo)：用(yong)儀(yi)器所配專用(yong)電(dian)(dian)(dian)源(yuan)線(xian)，輸(shu)入50HZ、220V交流電(dian)(dian)(dian)源(yuan)。儀(yi)器使用(yong)時，應(ying)獨立(li)使用(yong)三(san)孔電(dian)(dian)(dian)源(yuan)插座(zuo)，插座(zuo)接(jie)地(di)線(xian)就近(jin)直接(jie)接(jie)地(di)。
3.保險(xian)座：儀器使用10A保險(xian)芯，損(sun)壞(huai)時應(ying)換同規(gui)格保險(xian)芯。
4.黑接(jie)線(xian)(xian)柱：測(ce)(ce)試(shi)時，用配套(tao)黑色測(ce)(ce)試(shi)線(xian)(xian)（Ф4插(cha)(cha)頭）插(cha)(cha)入此插(cha)(cha)孔，另(ling)一端測(ce)(ce)試(shi)夾接(jie)系統(tong)地。
5.紅(hong)接線(xian)柱：測(ce)(ce)(ce)試(shi)時，用配套紅(hong)色測(ce)(ce)(ce)試(shi)線(xian)（Ф4插頭）插入(ru)此插孔，另一端測(ce)(ce)(ce)試(shi)夾接被測(ce)(ce)(ce)電纜芯(xin)線(xian)。
6.表頭：指示(shi)輸出電流大小。
7.輸(shu)出調節：用于調整主機電流大(da)小，使用時根據測試電纜長(chang)短(duan)及接收(shou)器指示大(da)小適當調節。順時針(zhen)旋轉輸(shu)出電流增(zeng)大(da)。
接收機各部(bu)分功能如(ru)下：
1.電(dian)源開關：接收機(ji)電(dian)源接通與關斷。
2.幅度調節：順時針旋(xuan)轉，接(jie)收機電表指(zhi)示值增(zeng)大，逆時針旋(xuan)轉，指(zhi)示值變小。
3.表(biao)頭：指示輸入(ru)信號幅度大小(xiao)與極性。
4.電源指(zhi)示(shi)燈：電源開關接(jie)通(tong)時，指(zhi)示(shi)燈亮。
三、BYST-230A電纜(lan)識別儀工作方法(fa)
電纜識(shi)別(bie)儀信(xin)號發生器由交流電源(yuan)供電，它對已(yi)斷(duan)電的、要識(shi)別(bie)的電纜加上固定周期單極(ji)性的直流脈沖。發生器輸出(chu)線(xian)連(lian)在(zai)電纜芯線(xian)和接地(di)(di)點或地(di)(di)釘上，該電纜線(xian)鎧裝(zhuang)與(yu)大地(di)(di)斷(duan)開(kai)，芯線(xian)在(zai)遠端與(yu)接地(di)(di)點或地(di)(di)釘相(xiang)連(lian)，該回路(lu)可傳導脈沖電流，它可由識(shi)別(bie)儀上的表(biao)頭讀出(chu)，電流大小由環(huan)(huan)路(lu)電阻(zu)決定，環(huan)(huan)路(lu)電阻(zu)應盡可能小。識(shi)別(bie)儀接線(xian)圖(tu)如(ru)圖(tu)2所示
圖2 識別儀接線(xian)圖
發(fa)射機(ji)(ji)與接收(shou)機(ji)(ji)開始正常工(gong)作后，卡鉗線圈中(zhong)感應(ying)的(de)電(dian)(dian)壓(ya)在接收(shou)機(ji)(ji)表(biao)頭中(zhong)顯示出(chu)來，表(biao)頭指針(zhen)(zhen)擺(bai)動方向(xiang)(xiang)可(ke)顯示電(dian)(dian)流(liu)(liu)方向(xiang)(xiang)，即只有電(dian)(dian)流(liu)(liu)流(liu)(liu)出(chu)的(de)這根電(dian)(dian)纜指針(zhen)(zhen)向(xiang)(xiang)右偏(pian)并(bing)且擺(bai)幅較大，這根就(jiu)是要(yao)找的(de)電(dian)(dian)纜。所有其它電(dian)(dian)纜只流(liu)(liu)過返(fan)回電(dian)(dian)流(liu)(liu)，指針(zhen)(zhen)向(xiang)(xiang)左偏(pian)并(bing)且擺(bai)幅極(ji)小。接收(shou)機(ji)(ji)上的(de)輸出(chu)調節(jie)旋鈕(niu)可(ke)調整信(xin)號強(qiang)度。
1.儀器供電
電纜識別(bie)儀(yi)主機(ji)由交流220V供(gong)電，接收(shou)機(ji)由一節(jie)9V電池供(gong)電、電池裝在(zai)接收(shou)機(ji)手把后蓋內。擰開后蓋兩側螺絲、拉出后蓋，可更換電池。
2.卡鉗
卡鉗是一電流變換器(qi)，鉗口內部尺寸為(wei)120mm。卡鉗側面有一箭頭，它應(ying)指(zhi)向被測電纜的遠端。
當電(dian)(dian)(dian)流(liu)(liu)流(liu)(liu)過測試電(dian)(dian)(dian)纜，在卡鉗內感應出(chu)電(dian)(dian)(dian)壓(ya)，電(dian)(dian)(dian)壓(ya)幅(fu)度由電(dian)(dian)(dian)流(liu)(liu)強度決(jue)定，其(qi)極性由電(dian)(dian)(dian)流(liu)(liu)方向決(jue)定。
3.安全測試
一定要進(jin)(jin)行(xing)以下安全測試(shi)，以避免造**員傷亡或損壞電(dian)(dian)(dian)纜識(shi)別儀及其它設備。使(shi)用電(dian)(dian)(dian)纜識(shi)別儀時，要對被測電(dian)(dian)(dian)纜進(jin)(jin)行(xing)帶(dai)電(dian)(dian)(dian)檢查(cha)，并確(que)保該(gai)電(dian)(dian)(dian)纜處于無(wu)電(dian)(dian)(dian)狀(zhuang)態。
將儀器(qi)接(jie)入被(bei)測電(dian)纜前，要對其附近末加(jia)保護的儀器(qi)或電(dian)纜進(jin)行安全檢查，并將這(zhe)些(xie)帶電(dian)部分用(yong)絕緣(yuan)材料進(jin)行安全保護。