電(dian)(dian)(dian)(dian)表(biao)(biao)(biao)的(de)接(jie)(jie)線(xian)形(xing)式(shi)很多,有(you)單相(xiang)(xiang)(xiang)電(dian)(dian)(dian)(dian)表(biao)(biao)(biao)的(de)接(jie)(jie)法(fa)(fa),也(ye)有(you)三(san)(san)相(xiang)(xiang)(xiang)電(dian)(dian)(dian)(dian)表(biao)(biao)(biao)的(de)接(jie)(jie)法(fa)(fa);有(you)直(zhi)接(jie)(jie)接(jie)(jie)線(xian)式(shi),也(ye)有(you)經過電(dian)(dian)(dian)(dian)流互(hu)感(gan)器和電(dian)(dian)(dian)(dian)壓(ya)互(hu)感(gan)器接(jie)(jie)線(xian)的(de)。其中,三(san)(san)相(xiang)(xiang)(xiang)電(dian)(dian)(dian)(dian)表(biao)(biao)(biao),主要計(ji)量(liang)的(de)是380V電(dian)(dian)(dian)(dian)壓(ya)的(de)三(san)(san)根火線(xian)的(de)“耗(hao)電(dian)(dian)(dian)(dian)量(liang)之和”,三(san)(san)相(xiang)(xiang)(xiang)電(dian)(dian)(dian)(dian)表(biao)(biao)(biao)有(you)三(san)(san)相(xiang)(xiang)(xiang)三(san)(san)線(xian)電(dian)(dian)(dian)(dian)表(biao)(biao)(biao)和三(san)(san)相(xiang)(xiang)(xiang)四線(xian)電(dian)(dian)(dian)(dian)表(biao)(biao)(biao)之分(fen)。下面(mian),就來了(le)解下三(san)(san)相(xiang)(xiang)(xiang)四線(xian)電(dian)(dian)(dian)(dian)表(biao)(biao)(biao)接(jie)(jie)線(xian)怎么接(jie)(jie),三(san)(san)相(xiang)(xiang)(xiang)四線(xian)電(dian)(dian)(dian)(dian)表(biao)(biao)(biao)互(hu)感(gan)器的(de)接(jie)(jie)法(fa)(fa)。
電(dian)表的(de)接(jie)線(xian)形式很多(duo),但(dan)是(shi)總的(de)來說,只有兩種回(hui)路(lu)(lu):電(dian)壓回(hui)路(lu)(lu)和(he)電(dian)流回(hui)路(lu)(lu)。電(dian)表接(jie)線(xian)的(de)一般原則是(shi):電(dian)流線(xian)圈(quan)與負(fu)(fu)載(zai)串聯,或接(jie)在電(dian)流互感(gan)器(qi)的(de)二次(ci)側(ce),電(dian)壓線(xian)圈(quan)與負(fu)(fu)載(zai)并聯或接(jie)在電(dian)壓互感(gan)器(qi)的(de)二次(ci)側(ce)。
三(san)(san)相(xiang)四線有(you)功電(dian)表(biao)由三(san)(san)個驅動部件組成,稱(cheng)三(san)(san)元件電(dian)表(biao),和單相(xiang)及(ji)三(san)(san)相(xiang)三(san)(san)線電(dian)表(biao)外(wai)觀上最大的不(bu)同是其共有(you)11個這么多接線端,此(ci)電(dian)表(biao)常用在動力和照(zhao)明混合的供電(dian)電(dian)路(lu)。接線圖如(ru)下:
上圖(左)為(wei)三相(xiang)四線(xian)有功電表直接(jie)(jie)接(jie)(jie)入,火線(xian)U、V、W分(fen)別接(jie)(jie)在1、4、7端(duan),3、6、9端(duan)接(jie)(jie)負(fu)載(zai),零線(xian)接(jie)(jie)10號(hao)端(duan),11號(hao)端(duan)接(jie)(jie)負(fu)載(zai)另一端(duan)。
上圖(右)為三相四線(xian)有功電(dian)(dian)表(biao)(biao)經電(dian)(dian)流(liu)(liu)互(hu)(hu)(hu)(hu)感(gan)(gan)器(qi)接(jie)(jie)入(ru),火(huo)線(xian)U、V、W分別(bie)接(jie)(jie)電(dian)(dian)流(liu)(liu)互(hu)(hu)(hu)(hu)感(gan)(gan)器(qi)一次(ci)(ci)(ci)側(ce)(ce)首端(duan)(duan)(duan)(duan)(duan)(duan)L1,一次(ci)(ci)(ci)側(ce)(ce)末(mo)端(duan)(duan)(duan)(duan)(duan)(duan)L2端(duan)(duan)(duan)(duan)(duan)(duan)接(jie)(jie)負載(zai),電(dian)(dian)度表(biao)(biao)1、4、7端(duan)(duan)(duan)(duan)(duan)(duan)分別(bie)接(jie)(jie)電(dian)(dian)流(liu)(liu)互(hu)(hu)(hu)(hu)感(gan)(gan)器(qi)二次(ci)(ci)(ci)側(ce)(ce)首端(duan)(duan)(duan)(duan)(duan)(duan)K1,3、6、9端(duan)(duan)(duan)(duan)(duan)(duan)分別(bie)接(jie)(jie)二次(ci)(ci)(ci)側(ce)(ce)末(mo)端(duan)(duan)(duan)(duan)(duan)(duan)K2,電(dian)(dian)表(biao)(biao)2、5、8端(duan)(duan)(duan)(duan)(duan)(duan)分別(bie)接(jie)(jie)電(dian)(dian)流(liu)(liu)互(hu)(hu)(hu)(hu)感(gan)(gan)器(qi)一次(ci)(ci)(ci)側(ce)(ce)L1端(duan)(duan)(duan)(duan)(duan)(duan),其連(lian)片應拆下。為保證(zheng)安(an)全,電(dian)(dian)流(liu)(liu)互(hu)(hu)(hu)(hu)感(gan)(gan)器(qi)二次(ci)(ci)(ci)側(ce)(ce)末(mo)端(duan)(duan)(duan)(duan)(duan)(duan)K2應分別(bie)接(jie)(jie)地(di)。右圖為接(jie)(jie)線(xian)圖的模(mo)擬演示,大(da)家注意電(dian)(dian)流(liu)(liu)互(hu)(hu)(hu)(hu)感(gan)(gan)器(qi)與電(dian)(dian)表(biao)(biao)的接(jie)(jie)線(xian)。
1、三相電源輸送的配線方法
三(san)相四線(xian)(xian)(xian)(xian)制(zhi)是指有(you)A、B、C、N,其中,N線(xian)(xian)(xian)(xian)是中線(xian)(xian)(xian)(xian),也(ye)叫(jiao)零線(xian)(xian)(xian)(xian)。N線(xian)(xian)(xian)(xian)是為了(le)從380V相間電(dian)壓中獲得220V線(xian)(xian)(xian)(xian)間電(dian)壓而設(she)的,有(you)的場合也(ye)可(ke)以用(yong)來進(jin)行零序電(dian)流檢測,以便進(jin)行三(san)相供(gong)電(dian)平衡的監控。A線(xian)(xian)(xian)(xian)用(yong)黃色(se),B線(xian)(xian)(xian)(xian)用(yong)藍(lan)色(se),C線(xian)(xian)(xian)(xian)用(yong)紅色(se),N線(xian)(xian)(xian)(xian)用(yong)褐(he)色(se),PE線(xian)(xian)(xian)(xian)用(yong)黃綠(lv)色(se)。
2、單相三線、三相四線、三相五線,三者有什么區別?
單相雙線----------1根火(huo)線1根零線
單(dan)相三線----------1根(gen)(gen)(gen)火線1根(gen)(gen)(gen)零線+1根(gen)(gen)(gen)地線
三相四線----------3根相線1根零線
三(san)相(xiang)五線(xian)----------3根(gen)(gen)相(xiang)線(xian)1根(gen)(gen)零線(xian)+1根(gen)(gen)地線(xian)
單相(xiang)電(dian)表,主要(yao)計(ji)量的是(shi)220V電(dian)壓的單根(gen)火線的“耗(hao)電(dian)量”,主要(yao)用在城鎮(zhen)居民(min)用電(dian),照(zhao)明用電(dian)。
三相電(dian)表,主要計(ji)量(liang)的(de)(de)(de)是380V電(dian)壓(ya)的(de)(de)(de)三根火線的(de)(de)(de)“耗(hao)電(dian)量(liang)之(zhi)和”,主要用(yong)(yong)在關口電(dian)能計(ji)量(liang),工礦商業企業等(deng)大的(de)(de)(de)用(yong)(yong)電(dian)單(dan)位,一般都在高壓(ya)線路里。它根據(ju)場合需要有(you)3線,4線和5線幾種方式:
三線----------3根(gen)火線(沒有零(ling)線N和接地線PE)
四線(xian)----------3根火(huo)線(xian)+1根零線(xian)N (TN-C系(xi)統(tong))
五(wu)線----------3根(gen)火線+1根(gen)零線N+1根(gen)接地線PE (TN-S系統)
3、三相電表為什么要加互感器?
一(yi)般小于100A的不需要加互感器(qi)(qi),而大(da)于100A加了互感器(qi)(qi)之后(hou)相當于把大(da)電(dian)(dian)流變(bian)成小電(dian)(dian)流后(hou)再進入(ru)電(dian)(dian)表(biao),這(zhe)個就不會燒壞電(dian)(dian)表(biao)。加了互感器(qi)(qi)后(hou)讀取電(dian)(dian)表(biao)數(shu)時應乘以互感器(qi)(qi)相應的倍數(shu)。
三(san)相四線(xian)(xian)(xian)制系統特點(dian)是:電源變壓器中性點(dian)接地,保(bao)護零線(xian)(xian)(xian)(PE)與工(gong)作零線(xian)(xian)(xian)(N)共用(簡稱PEN)。
適用于(yu)三相負(fu)荷基本平衡(heng)場合,如果三相負(fu)荷不平衡(heng),則PEN線中(zhong)有不平衡(heng)電(dian)流(liu),再加(jia)一些負(fu)荷設(she)備引起的(de)諧波電(dian)流(liu)也會注入PEN,從而中(zhong)性線N帶(dai)電(dian),且極有可能高于(yu)50V,它不但使設(she)備機殼帶(dai)電(dian),對(dui)人身造成不安全(quan),而且還(huan)無法取得穩定的(de)基準電(dian)位;
應將PEN線重復接地(di)(di),其作用(yong)是當(dang)接零(ling)的設備發生相(xiang)與外殼接觸時(shi),可以(yi)有(you)效地(di)(di)降低零(ling)線對(dui)地(di)(di)電壓。
缺陷:
(1)當三(san)相(xiang)負載不平衡時,在零(ling)(ling)線(xian)上出現不平衡電流,零(ling)(ling)線(xian)對地(di)呈(cheng)現電壓,觸(chu)及零(ling)(ling)線(xian)可(ke)能導致(zhi)觸(chu)電事故。
(2)通(tong)過(guo)漏(lou)電保(bao)護(hu)開(kai)(kai)關(guan)的(de)零線,只能作(zuo)(zuo)為(wei)工(gong)(gong)作(zuo)(zuo)零線,不能作(zuo)(zuo)為(wei)電氣(qi)設備的(de)保(bao)護(hu)零線,這(zhe)是由于(yu)漏(lou)電開(kai)(kai)關(guan)的(de)工(gong)(gong)作(zuo)(zuo)原理所(suo)決定(ding)的(de)。
(3)對接(jie)(jie)有二極(ji)漏(lou)電(dian)(dian)(dian)保(bao)(bao)護(hu)開關(guan)的單相用電(dian)(dian)(dian)設備,如用于(yu) TN-C系統中其金屬外殼的保(bao)(bao)護(hu)零(ling)線(xian),嚴禁與該電(dian)(dian)(dian)路的工作零(ling)線(xian)相連接(jie)(jie),也不允許接(jie)(jie)在(zai)漏(lou)電(dian)(dian)(dian)保(bao)(bao)護(hu)開關(guan)前面的 PEN線(xian)上,但(dan)在(zai)使用中極(ji)易(yi)發生誤(wu)接(jie)(jie)。
(4)重復接地裝置的連接線,嚴禁與通過漏電開關的工作零線相連接。TN-S供電系統,將工作零線與保護零線完全分開,從而克服了TN-C供電系統的缺陷,所以現在施工現場已經不再使用TN-C系統,推薦使用TN-S系統(tong)。
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