為了(le)做(zuo)好低(di)壓(ya)(ya)配電(dian)(dian)(dian)(dian)系統(tong)的(de)(de)防(fang)(fang)雷(lei)，便(bian)于浪涌保護器的(de)(de)選(xuan)型、防(fang)(fang)雷(lei)工(gong)程(cheng)的(de)(de)設計與(yu)施工(gong)，我們首先要(yao)了(le)解低(di)壓(ya)(ya)配電(dian)(dian)(dian)(dian)系統(tong)的(de)(de)接(jie)地(di)型式。【鈞和電(dian)(dian)(dian)(dian)子?浪涌保護器】今天為您分享“低(di)壓(ya)(ya)配電(dian)(dian)(dian)(dian)系統(tong)的(de)(de)TN接(jie)地(di)型式”。

根據國際電(dian)(dian)工委員(yuan)會（IEC）關于電(dian)(dian)氣(qi)裝置(zhi)的(de)規定，按照(zhao)電(dian)(dian)源中性點(dian)的(de)接地狀態、中性線（N線）和保護線(PE線)的(de)配置(zhi)方式(shi)，我國現行規程(cheng)將低壓配電(dian)(dian)系(xi)統(tong)(tong)接地分(fen)為(wei)(wei)TN系(xi)統(tong)(tong)、TT系(xi)統(tong)(tong)和IT系(xi)統(tong)(tong)三種(zhong)型(xing)式(shi)，其中TN系(xi)統(tong)(tong)分(fen)為(wei)(wei)TN-S系(xi)統(tong)(tong)、TN-C系(xi)統(tong)(tong)和TN-C-S系(xi)統(tong)(tong)三種(zhong)。

TN系統(tong)低壓配電(dian)系統(tong)是電(dian)源(yuan)端有(you)一點直接接地，用電(dian)設備的外露可導電(dian)部分通(tong)過(guo)中(zhong)性線(xian)（N線(xian)）或保(bao)護線(xian)（PE線(xian)）與(yu)電(dian)源(yuan)端的接地電(dian)連(lian)接。按照中(zhong)性線(xian)與(yu)保(bao)護線(xian)的配置方式(shi)，TN系統(tong)有(you)以下三種(zhong)型式(shi)：

一、TN-C系(xi)統，即三相四線制保(bao)護接(jie)零系(xi)統

在TN-C系統(tong)(tong)中，整個系統(tong)(tong)的(de)(de)中性線(xian)(xian)(xian)與保(bao)(bao)護(hu)線(xian)(xian)(xian)合(he)并(bing)為PEN線(xian)(xian)(xian)，又稱為保(bao)(bao)護(hu)中性線(xian)(xian)(xian)；該(gai)系統(tong)(tong)具有簡單、經(jing)濟的(de)(de)優點。當(dang)發生接(jie)地短(duan)路故(gu)(gu)障時(shi)(shi)，故(gu)(gu)障電(dian)流(liu)大，可采(cai)用過電(dian)流(liu)保(bao)(bao)護(hu)電(dian)器切(qie)斷(duan)電(dian)源，來(lai)保(bao)(bao)證安全。但在有單相(xiang)負(fu)荷或(huo)三相(xiang)不平衡負(fu)荷以及(ji)由諧波(bo)電(dian)流(liu)負(fu)荷的(de)(de)線(xian)(xian)(xian)路中，PEN線(xian)(xian)(xian)流(liu)過電(dian)流(liu)所產生的(de)(de)壓(ya)降會加(jia)在電(dian)器設備(bei)的(de)(de)金(jin)屬外(wai)殼或(huo)線(xian)(xian)(xian)路金(jin)屬套(tao)管上，對(dui)敏(min)感性的(de)(de)電(dian)子信息設備(bei)不利。同時(shi)(shi)由于PEN線(xian)(xian)(xian)在同一(yi)建筑內(nei)往往相(xiang)互連通，因此(ci)，當(dang)PEN線(xian)(xian)(xian)斷(duan)線(xian)(xian)(xian)或(huo)相(xiang)線(xian)(xian)(xian)直接(jie)與大地短(duan)路時(shi)(shi)，都將呈(cheng)現相(xiang)當(dang)高(gao)的(de)(de)對(dui)地故(gu)(gu)障電(dian)壓(ya)，這時(shi)(shi)事故(gu)(gu)范圍可能(neng)擴(kuo)大。

由于TN-C系統(tong)安全水平較低，在民用建筑中這(zhe)種接地(di)型式已經不再使用，僅在有專業人員維護管理的一(yi)般(ban)工(gong)業廠房中應用。

二、TN-S系統(tong)，即三相五(wu)線制系統(tong)

在TN-S系(xi)統(tong)中(zhong)，整(zheng)個系(xi)統(tong)的(de)中(zhong)性(xing)線(xian)與保(bao)護(hu)線(xian)是分開(kai)的(de)。由于(yu)正常工(gong)作時，PE線(xian)不通(tong)過負荷(he)電(dian)流，與PE線(xian)相連的(de)電(dian)氣設備(bei)的(de)外露可導(dao)電(dian)部分在正常工(gong)作時不帶電(dian)位，所以適用于(yu)數據處理和(he)電(dian)子(zi)信息設備(bei)的(de)供電(dian)。在民用建筑(zhu)內，由于(yu)目前家用電(dian)氣都提供接保(bao)護(hu)線(xian)用的(de)三(san)眼插頭(tou)，采用TN-S系(xi)統(tong)供電(dian)，既方(fang)便又安全。

三、TN-C-S系統

該(gai)系(xi)統中有(you)一(yi)部(bu)分中性(xing)(xing)線(xian)(xian)(xian)(xian)與(yu)(yu)保(bao)護線(xian)(xian)(xian)(xian)是(shi)(shi)合一(yi)的(de)，有(you)一(yi)部(bu)分是(shi)(shi)分開(kai)(kai)的(de)。通常PEN線(xian)(xian)(xian)(xian)在電(dian)纜進戶處起分為保(bao)護線(xian)(xian)(xian)(xian)和(he)中性(xing)(xing)線(xian)(xian)(xian)(xian)，分開(kai)(kai)后(hou)N線(xian)(xian)(xian)(xian)應(ying)對地絕緣(yuan)。PEN線(xian)(xian)(xian)(xian)自分開(kai)(kai)后(hou)，PE線(xian)(xian)(xian)(xian)與(yu)(yu)N線(xian)(xian)(xian)(xian)不能再合并(bing)，否(fou)則將(jiang)喪失分開(kai)(kai)后(hou)形成的(de)TN-S系(xi)統的(de)優點。為防止(zhi)分開(kai)(kai)后(hou)的(de)PE線(xian)(xian)(xian)(xian)和(he)N線(xian)(xian)(xian)(xian)混淆，應(ying)按導體(ti)的(de)顏色和(he)數字標(biao)識(shi)規(gui)定，給PE線(xian)(xian)(xian)(xian)和(he)PEN線(xian)(xian)(xian)(xian)涂以黃(huang)綠相間的(de)色標(biao)，給N線(xian)(xian)(xian)(xian)涂以淺藍色色標(biao)。

TN-C-S是一種(zhong)廣(guang)泛應用(yong)(yong)的(de)(de)接地(di)型(xing)式。當民用(yong)(yong)建筑由裝設(she)在(zai)戶外的(de)(de)變(bian)(bian)壓器(qi)供電時，由變(bian)(bian)壓器(qi)進入(ru)建筑物的(de)(de)配(pei)電線(xian)路可采(cai)用(yong)(yong)TN-C系(xi)統(tong)，進入(ru)建筑物后經重復接地(di)改為TN-S系(xi)統(tong)。這(zhe)種(zhong)系(xi)統(tong)線(xian)路簡單又能保(bao)證一定的(de)(de)安全水平(ping)。在(zai)電源側的(de)(de)PEN導體上難(nan)免有(you)一定電壓降，但對于固定設(she)備及民用(yong)(yong)建筑的(de)(de)用(yong)(yong)電設(she)備不會(hui)有(you)什么影響。

備注：

1.各種接地(di)型(xing)式中(zhong)字母的代號意義(yi)為：

T表示低壓系統電源端有一點直接(jie)接(jie)地；

I表示低壓系統電(dian)源端的所有帶電(dian)部分與地絕(jue)緣或有一點(dian)經阻(zu)抗(kang)接地；

2.第二個字母表示(shi)電氣裝置的外露可導電部分與地(di)的關系：

T表示電(dian)(dian)氣(qi)裝(zhuang)置的外露(lu)可導電(dian)(dian)部分直接接地(di)，且此接地(di)點在電(dian)(dian)氣(qi)上獨立于電(dian)(dian)源(yuan)的接地(di)點；

N表示(shi)外露可導電部分與電源(yuan)端(duan)的接(jie)(jie)地(di)點有直接(jie)(jie)電氣連接(jie)(jie)。

3.橫線(xian)后的字(zi)母用來(lai)表(biao)示中(zhong)性(xing)線(xian)與保護(hu)線(xian)的組合情況：

S表示(shi)中性線(xian)和保護(hu)線(xian)是分開(kai)的；

C表示中(zhong)性線和保護線是合一的(de)。