零線：
通常電力(li)傳(chuan)輸(shu)是以三(san)(san)(san)(san)相四線的(de)方式，三(san)(san)(san)(san)相電的(de)三(san)(san)(san)(san)根頭稱(cheng)為相線，三(san)(san)(san)(san)相電的(de)三(san)(san)(san)(san)根尾連接(jie)在一(yi)起稱(cheng)中性線也(ye)叫'零(ling)線'。叫零(ling)線的(de)原(yuan)因是三(san)(san)(san)(san)相平衡時刻中性線中沒有電流通過了，再(zai)就是它直接(jie)或間(jian)接(jie)的(de)接(jie)到大(da)地(di)，跟(gen)大(da)地(di)電壓也(ye)接(jie)近(jin)零(ling)。
三相四線制:
低(di)壓配電(dian)(dian)(dian)(dian)網中(zhong)(zhong)(zhong)(zhong)，輸電(dian)(dian)(dian)(dian)線(xian)(xian)(xian)(xian)(xian)(xian)路(lu)一(yi)(yi)般采用(yong)三相(xiang)(xiang)四線(xian)(xian)(xian)(xian)(xian)(xian)制(zhi)，其中(zhong)(zhong)(zhong)(zhong)三條線(xian)(xian)(xian)(xian)(xian)(xian)路(lu)分別代表A,B,C三相(xiang)(xiang)，另一(yi)(yi)條是(shi)中(zhong)(zhong)(zhong)(zhong)性(xing)線(xian)(xian)(xian)(xian)(xian)(xian)N(如果(guo)(guo)該回路(lu)電(dian)(dian)(dian)(dian)源(yuan)側的(de)(de)(de)中(zhong)(zhong)(zhong)(zhong)性(xing)點接(jie)地(di)，則中(zhong)(zhong)(zhong)(zhong)性(xing)線(xian)(xian)(xian)(xian)(xian)(xian)也稱為零(ling)線(xian)(xian)(xian)(xian)(xian)(xian)(老式(shi)叫法(fa)，應逐漸避免，改稱PEN)，如果(guo)(guo)不接(jie)地(di)，則從嚴格意義上來(lai)說，中(zhong)(zhong)(zhong)(zhong)性(xing)線(xian)(xian)(xian)(xian)(xian)(xian)不能稱為零(ling)線(xian)(xian)(xian)(xian)(xian)(xian))。在進(jin)(jin)入用(yong)戶的(de)(de)(de)單相(xiang)(xiang)輸電(dian)(dian)(dian)(dian)線(xian)(xian)(xian)(xian)(xian)(xian)路(lu)中(zhong)(zhong)(zhong)(zhong)，有(you)兩(liang)條線(xian)(xian)(xian)(xian)(xian)(xian)，一(yi)(yi)條我們稱為相(xiang)(xiang)線(xian)(xian)(xian)(xian)(xian)(xian)L，另一(yi)(yi)條我們稱為中(zhong)(zhong)(zhong)(zhong)線(xian)(xian)(xian)(xian)(xian)(xian)N，中(zhong)(zhong)(zhong)(zhong)線(xian)(xian)(xian)(xian)(xian)(xian)正常情況下要通過電(dian)(dian)(dian)(dian)流以構成單相(xiang)(xiang)線(xian)(xian)(xian)(xian)(xian)(xian)路(lu)中(zhong)(zhong)(zhong)(zhong)電(dian)(dian)(dian)(dian)流的(de)(de)(de)回路(lu)。而(er)三相(xiang)(xiang)系統中(zhong)(zhong)(zhong)(zhong)，三相(xiang)(xiang)平(ping)衡時，中(zhong)(zhong)(zhong)(zhong)性(xing)線(xian)(xian)(xian)(xian)(xian)(xian)(零(ling)線(xian)(xian)(xian)(xian)(xian)(xian))是(shi)無電(dian)(dian)(dian)(dian)流的(de)(de)(de)，故稱三相(xiang)(xiang)四線(xian)(xian)(xian)(xian)(xian)(xian)制(zhi);在380V低(di)壓配電(dian)(dian)(dian)(dian)網中(zhong)(zhong)(zhong)(zhong)為了從380V線(xian)(xian)(xian)(xian)(xian)(xian)間電(dian)(dian)(dian)(dian)壓中(zhong)(zhong)(zhong)(zhong)獲得220V相(xiang)(xiang)間電(dian)(dian)(dian)(dian)壓而(er)設N線(xian)(xian)(xian)(xian)(xian)(xian)，有(you)的(de)(de)(de)場合也可以用(yong)來(lai)進(jin)(jin)行零(ling)序(xu)電(dian)(dian)(dian)(dian)流檢(jian)測，以便進(jin)(jin)行三相(xiang)(xiang)供電(dian)(dian)(dian)(dian)平(ping)衡的(de)(de)(de)監控。
配電(dian)室變壓器輸出三根(gen)火(huo)(huo)(huo)線(xian)、一根(gen)中(zhong)性線(xian)(接地(di)則也(ye)稱為(wei)(wei)為(wei)(wei)零線(xian))。三根(gen)火(huo)(huo)(huo)線(xian)(相(xiang)線(xian))每一根(gen)與零線(xian)是220v稱單相(xiang)。火(huo)(huo)(huo)線(xian)與火(huo)(huo)(huo)線(xian)為(wei)(wei)雙(shuang)相(xiang)(兩相(xiang))380v。三根(gen)火(huo)(huo)(huo)線(xian)全使用(yong)為(wei)(wei)三相(xiang)，每兩根(gen)都是380v。由一條火(huo)(huo)(huo)線(xian)與一條零線(xian)組成的電(dian)路稱為(wei)(wei)單相(xiang)電(dian)路。由三條火(huo)(huo)(huo)線(xian)組成的電(dian)路稱為(wei)(wei)三相(xiang)電(dian)路。兩相(xiang)中(zhong)國(guo)不使用(yong)。
三相五線制
是(shi)指A、B、C、N和(he)(he)PE線(xian)(xian)(xian)，其中(zhong)，PE線(xian)(xian)(xian)是(shi)保(bao)護(hu)地(di)(di)線(xian)(xian)(xian)，也叫安全(quan)線(xian)(xian)(xian)，是(shi)專門用(yong)于(yu)接到(dao)諸(zhu)如設備外殼(ke)等保(bao)證用(yong)電安全(quan)之(zhi)用(yong)的(de)(de)。PE線(xian)(xian)(xian)在供(gong)電變壓器側和(he)(he)N線(xian)(xian)(xian)接到(dao)一起，但進入用(yong)戶側后絕不能當作(zuo)(zuo)零(ling)線(xian)(xian)(xian)使用(yong)，否則，發生混亂后就與三(san)(san)相四線(xian)(xian)(xian)制無異了。由于(yu)這種混亂容(rong)(rong)易(yi)讓人喪失警惕，可能在實際中(zhong)更加容(rong)(rong)易(yi)發生觸電事(shi)故。零(ling)線(xian)(xian)(xian)與PE線(xian)(xian)(xian)的(de)(de)根本區別(bie)在于(yu)：零(ling)線(xian)(xian)(xian)構成回路，PE線(xian)(xian)(xian)僅起保(bao)護(hu)作(zuo)(zuo)用(yong)。現在民用(yong)住宅供(gong)電已經(jing)規定要(yao)使用(yong)三(san)(san)相五線(xian)(xian)(xian)制，如果(guo)你的(de)(de)不是(shi)，可以要(yao)求(qiu)整改。為了安全(quan)，要(yao)斬(zhan)釘截鐵地(di)(di)要(yao)求(qiu)使用(yong)三(san)(san)相五線(xian)(xian)(xian)制!
顏色規范
應(ying)用中(zhong)最好使用標準、規(gui)范的(de)導線(xian)顏(yan)色(se)(se)：A相(xiang)用黃色(se)(se)，B相(xiang)用綠色(se)(se)，C相(xiang)用紅色(se)(se)，N線(xian)用淡藍色(se)(se)，PE線(xian)用黃綠雙色(se)(se)。在(zai)進入用戶的(de)單相(xiang)輸電(dian)(dian)線(xian)路(lu)中(zhong)，有兩條線(xian)，一條我們稱為(wei)火線(xian)L(Line)，用棕色(se)(se);另一條為(wei)零線(xian)N(Neutral中(zhong)性線(xian))，用淡藍色(se)(se)，中(zhong)線(xian)正常(chang)情況下要通過電(dian)(dian)流(liu)以(yi)構成(cheng)單相(xiang)線(xian)路(lu)中(zhong)電(dian)(dian)流(liu)的(de)回路(lu);另外(wai)三孔插(cha)座上(左零有火，中(zhong)為(wei)地(di))，會有接地(di)線(xian)，將一些電(dian)(dian)器的(de)外(wai)殼(ke)接地(di)，即(ji)為(wei)接地(di)保(bao)護線(xian)PE，用黃綠雙色(se)(se)線(xian)。
重復接地
不論(lun)N線(xian)(xian)(中性線(xian)(xian))還是(shi)PE線(xian)(xian)(保(bao)護(hu)接(jie)地(di)線(xian)(xian))，在(zai)用(yong)戶側(ce)都要(yao)采用(yong)重(zhong)復接(jie)地(di)，以提高可(ke)靠性。但是(shi)，重(zhong)復接(jie)地(di)只是(shi)重(zhong)復接(jie)地(di)，它只能在(zai)接(jie)地(di)點或靠近接(jie)地(di)的(de)位置接(jie)到一起，但絕不表明可(ke)以在(zai)任意位置特別是(shi)戶內可(ke)以接(jie)到一起。這一點一定(ding)要(yao)切記!
“單相三線”：
是火線L、零(ling)線N和(he)接地(di)線GND。L和(he)N之間電(dian)(dian)壓(ya)為220V交流(liu)電(dian)(dian)。也就是單相(xiang)交流(liu)電(dian)(dian)。民用(yong)電(dian)(dian)源都是采用(yong)單相(xiang)交流(liu)220V電(dian)(dian)壓(ya)供電(dian)(dian)。
“雙相三線”：
是指(zhi)兩(liang)根火線L1和L2加(jia)一根零線GND。L1和L2之間(jian)電(dian)壓為380V交流電(dian)。
可以將插座開關上的火線和零線互換嗎?
實際上，如果采用(yong)兩芯插(cha)頭(中國(guo)國(guo)家(jia)標準之一(yi))，無所謂互換(huan)的。唯一(yi)的問題，可能導(dao)致用(yong)電器的電源開關切斷零(ling)線，從而使(shi)得電器在關斷狀態下帶電，安(an)全(quan)隱患較(jiao)大。但目前(qian)普遍采用(yong)雙刀(dao)開關，幾無影響。
零線接地嗎?
零線不(bu)允許(xu)任何個(ge)人擅自接地,只允許(xu)在(zai)變壓器端接地。
即(ji)比(bi)如(ru)高壓送電(dian)過來(10KV或20KV這些(xie))然后在(zai)變(bian)(bian)電(dian)臺的地(di)(di)(di)(di)(di)方(fang)，將低壓輸(shu)出繞組(zu)(3相(xiang)380V)中的中性(xing)(xing)線(xian)(零(ling)線(xian))接(jie)(jie)(jie)地(di)(di)(di)(di)(di)，為了(le)是保持(chi)3相(xiang)能(neng)夠由于零(ling)線(xian)對地(di)(di)(di)(di)(di)放(fang)電(dian)，而(er)使三相(xiang)平(ping)衡(heng)，如(ru)果零(ling)線(xian)不(bu)接(jie)(jie)(jie)地(di)(di)(di)(di)(di)那么負載不(bu)平(ping)衡(heng)時(shi)中性(xing)(xing)點就會(hui)漂移，一旦漂移就會(hui)導(dao)致(zhi)某一相(xiang)電(dian)壓過高燒(shao)毀設(she)備。而(er)接(jie)(jie)(jie)入用戶的設(she)備通常都(dou)無(wu)法經受這些(xie)電(dian)壓變(bian)(bian)化(hua)。所以變(bian)(bian)壓器端必須接(jie)(jie)(jie)地(di)(di)(di)(di)(di)，但只允許一次接(jie)(jie)(jie)地(di)(di)(di)(di)(di)，即(ji)在(zai)變(bian)(bian)壓器的地(di)(di)(di)(di)(di)方(fang)接(jie)(jie)(jie)，其他地(di)(di)(di)(di)(di)方(fang)禁止(zhi)接(jie)(jie)(jie)地(di)(di)(di)(di)(di)。用戶端是絕對禁止(zhi)接(jie)(jie)(jie)地(di)(di)(di)(di)(di)的，如(ru)果你零(ling)線(xian)接(jie)(jie)(jie)地(di)(di)(di)(di)(di)，假設(she)安裝(zhuang)了(le)漏電(dian)保護(hu)開(kai)關，保護(hu)開(kai)關會(hui)動作，而(er)如(ru)果你安裝(zhuang)了(le)一些(xie)保護(hu)斷路器，那么斷路器可能(neng)不(bu)會(hui)動作，甚至(zhi)電(dian)流(liu)超載也不(bu)會(hui)。
什么是變壓器中性點?(中性點接地，則為零線)
三相電力變壓器的一(yi)次側(初級)或二次側(次級)的三相繞組作星形(xing)聯(lian)結時(shi)三相繞組接(jie)入(或接(jie)出)電源，末端并聯(lian)成一(yi)點(dian)(dian)(dian)，這個點(dian)(dian)(dian)就(jiu)是中性(xing)點(dian)(dian)(dian).在三相四線供電線路中，中性(xing)點(dian)(dian)(dian)應接(jie)地(di)，又稱為(wei)零(ling)線.
Tips:
所謂交流(liu)電(dian)，一般指(zhi)大小(xiao)和方向隨時間作(zuo)周期性變(bian)化的電(dian)壓(ya)或電(dian)流(liu)。它(ta)的最(zui)基本的形式是正弦電(dian)流(liu)。
當沒(mei)有(you)形成回(hui)路(lu)(lu)時(shi)，火(huo)線有(you)隨正(zheng)弦上下(xia)波動的電(dian)(dian)壓，但沒(mei)有(you)電(dian)(dian)流(liu)，零(ling)線中也(ye)沒(mei)有(you)電(dian)(dian)流(liu)，而且零(ling)線此時(shi)對地電(dian)(dian)壓一(yi)般為0V;當220v電(dian)(dian)壓形成回(hui)路(lu)(lu)，若零(ling)線接(jie)地良(liang)好，電(dian)(dian)壓很低，可(ke)以(yi)忽略，若接(jie)地不良(liang)可(ke)能會出(chu)現較大壓差，此時(shi)零(ling)線、火(huo)線均有(you)電(dian)(dian)流(liu)流(liu)過。