LED顯示屏是的主體元件是LED和驅動芯片,屬于微電子產品的集合體,LED的工作電壓在5V左右,一般工作電流為20毫安以下。它的工作特性決定了它面對靜電和異常電壓或電流沖擊的抗性十分脆弱。這就需要我們在生產和使用過程中認識到這一點并給予足夠的重視,采取措施對led顯示屏進行保護。而電源接地是LED顯示屏最常用的一種保護方法。下面鄭州LED顯示屏小編來給大家講解一下吧!
為(wei)(wei)(wei)什么電(dian)(dian)(dian)(dian)源(yuan)要接(jie)(jie)地(di)(di)?這(zhe)個(ge)(ge)和(he)開(kai)關(guan)電(dian)(dian)(dian)(dian)源(yuan)的(de)(de)工(gong)作模式有關(guan),我們LED顯示(shi)屏開(kai)關(guan)電(dian)(dian)(dian)(dian)源(yuan)是(shi)一(yi)(yi)種(zhong)通過濾(lv)(lv)(lv)波—整(zheng)流—脈沖調制—輸(shu)出整(zheng)流—濾(lv)(lv)(lv)波等(deng)一(yi)(yi)系列(lie)手(shou)段將交流(AC)220V市電(dian)(dian)(dian)(dian)轉化成(cheng)直流(DC)5V直流電(dian)(dian)(dian)(dian)源(yuan)穩(wen)定(ding)輸(shu)出的(de)(de)一(yi)(yi)種(zhong)設備。為(wei)(wei)(wei)了保(bao)證電(dian)(dian)(dian)(dian)源(yuan)AC/DC轉化的(de)(de)穩(wen)定(ding)性,電(dian)(dian)(dian)(dian)源(yuan)廠家按照國家3C強制標準在(zai)(zai)AC220V輸(shu)入(ru)端的(de)(de)電(dian)(dian)(dian)(dian)路設計中,從火線至(zhi)地(di)(di)線跨接(jie)(jie)一(yi)(yi)個(ge)(ge)EMI濾(lv)(lv)(lv)波電(dian)(dian)(dian)(dian)路。以(yi)(yi)保(bao)證AC220V輸(shu)入(ru)的(de)(de)穩(wen)定(ding)性,所(suo)(suo)(suo)以(yi)(yi)所(suo)(suo)(suo)有的(de)(de)電(dian)(dian)(dian)(dian)源(yuan)在(zai)(zai)工(gong)作是(shi)都會(hui)存在(zai)(zai)濾(lv)(lv)(lv)波漏(lou)(lou)電(dian)(dian)(dian)(dian),單個(ge)(ge)電(dian)(dian)(dian)(dian)源(yuan)的(de)(de)漏(lou)(lou)電(dian)(dian)(dian)(dian)流的(de)(de)3.5mA左右。漏(lou)(lou)電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)壓約為(wei)(wei)(wei)110V。在(zai)(zai)顯示(shi)屏不(bu)(bu)接(jie)(jie)地(di)(di)的(de)(de)情(qing)況下,漏(lou)(lou)電(dian)(dian)(dian)(dian)流不(bu)(bu)但可能引(yin)起芯(xin)片損(sun)壞(huai)或(huo)者燈(deng)管(guan)燒壞(huai)。如果(guo)使(shi)用20個(ge)(ge)電(dian)(dian)(dian)(dian)源(yuan)以(yi)(yi)上,累加的(de)(de)漏(lou)(lou)電(dian)(dian)(dian)(dian)流達到70mA以(yi)(yi)上。足(zu)以(yi)(yi)導致漏(lou)(lou)電(dian)(dian)(dian)(dian)保(bao)護器(qi)動(dong)作,切斷供電(dian)(dian)(dian)(dian)。這(zhe)個(ge)(ge)也(ye)是(shi)為(wei)(wei)(wei)什么我們顯示(shi)屏無法使(shi)用漏(lou)(lou)電(dian)(dian)(dian)(dian)保(bao)護器(qi)的(de)(de)原因。如果(guo)不(bu)(bu)接(jie)(jie)漏(lou)(lou)保(bao)而且顯示(shi)屏不(bu)(bu)接(jie)(jie)地(di)(di),電(dian)(dian)(dian)(dian)源(yuan)疊加的(de)(de)漏(lou)(lou)電(dian)(dian)(dian)(dian)流將超過人(ren)體(ti)安全電(dian)(dian)(dian)(dian)流,110V的(de)(de)電(dian)(dian)(dian)(dian)壓足(zu)以(yi)(yi)致人(ren)死地(di)(di)!而接(jie)(jie)地(di)(di)后,電(dian)(dian)(dian)(dian)源(yuan)外殼(ke)電(dian)(dian)(dian)(dian)壓對(dui)人(ren)體(ti)接(jie)(jie)近(jin)0。表明電(dian)(dian)(dian)(dian)源(yuan)與人(ren)體(ti)之間不(bu)(bu)存在(zai)(zai)電(dian)(dian)(dian)(dian)位差,漏(lou)(lou)電(dian)(dian)(dian)(dian)流被導入(ru)大地(di)(di)。所(suo)(suo)(suo)以(yi)(yi),LED顯示(shi)屏必須接(jie)(jie)地(di)(di)。
但(dan)是經常有客戶采用錯(cuo)誤的接地方(fang)法(fa)為顯示屏(ping)接地,常見(jian)的有:
1、認為戶外立柱式(shi)結構(gou)的立柱下端是與(yu)大地連(lian)接,所以不需(xu)要(yao)在做(zuo)顯示屏接地;
2、認為電源是鎖在(zai)箱體上,而(er)箱體之間是相(xiang)互用鎖扣與結構連接,所以結構接地(di)就(jiu)代表(biao)電源也接地(di)。
此兩(liang)類做法存(cun)在誤區,我們(men)的(de)(de)立柱是(shi)(shi)與地基的(de)(de)地腳螺栓保持連(lian)接(jie),而地腳螺栓是(shi)(shi)預(yu)埋在混(hun)凝土(tu)里面(mian)的(de)(de),混(hun)凝土(tu)的(de)(de)電(dian)(dian)阻(zu)在100-500Ω的(de)(de)范(fan)圍(wei)內,接(jie)地電(dian)(dian)阻(zu)過高(gao)將導(dao)致(zhi)(zhi)漏電(dian)(dian)流泄放不(bu)及(ji)時或(huo)存(cun)在殘(can)留。我們(men)的(de)(de)箱(xiang)體(ti)(ti)(ti)表(biao)面(mian)有噴涂油漆,而油漆是(shi)(shi)電(dian)(dian)的(de)(de)不(bu)良導(dao)體(ti)(ti)(ti),將會導(dao)致(zhi)(zhi)箱(xiang)體(ti)(ti)(ti)連(lian)接(jie)接(jie)地的(de)(de)接(jie)觸不(bu)良或(huo)接(jie)地電(dian)(dian)阻(zu)升高(gao),有可能出現電(dian)(dian)火花干擾屏體(ti)(ti)(ti)信號。隨著時間的(de)(de)推移,箱(xiang)體(ti)(ti)(ti)或(huo)結構表(biao)面(mian)將會出現氧化(hua)和銹蝕,螺絲等固定件(jian)也隨著溫差變化(hua)導(dao)致(zhi)(zhi)的(de)(de)熱脹冷縮逐漸(jian)松(song)動。將會導(dao)致(zhi)(zhi)結構接(jie)地的(de)(de)效(xiao)(xiao)果減弱甚至(zhi)完全(quan)失效(xiao)(xiao)。形成安(an)全(quan)隱患。導(dao)致(zhi)(zhi)漏流觸電(dian)(dian)、芯(xin)片受(shou)干擾損壞等安(an)全(quan)事故的(de)(de)發生。
那么,標準(zhun)的接(jie)地(di)應該是怎(zen)樣的呢?如下所示:電(dian)源輸入端(duan)(duan)有3個接(jie)線(xian)端(duan)(duan)子,分別(bie)是火線(xian)端(duan)(duan)子、零線(xian)端(duan)(duan)子和接(jie)地(di)端(duan)(duan)子。正確的接(jie)地(di)做法(fa)是使(shi)用(yong)接(jie)地(di)專(zhuan)用(yong)的黃綠雙色線(xian)將所有電(dian)源地(di)線(xian)端(duan)(duan)子串接(jie)并鎖緊,然后(hou)引出(chu)連接(jie)至接(jie)地(di)端(duan)(duan)。
如果現(xian)場(chang)(chang)沒有接(jie)(jie)(jie)地(di)(di)端子,可(ke)以(yi)(yi)連接(jie)(jie)(jie)至(zhi)鐵(tie)質自來(lai)水管或(huo)(huo)鐵(tie)質下水管道(dao)等(deng)埋設與大(da)(da)地(di)(di)并與大(da)(da)地(di)(di)保(bao)(bao)持良好接(jie)(jie)(jie)觸的管道(dao)上,為保(bao)(bao)證接(jie)(jie)(jie)觸良好應(ying)在此類自然(ran)接(jie)(jie)(jie)地(di)(di)體(ti)上焊接(jie)(jie)(jie)接(jie)(jie)(jie)線端子,然(ran)后將地(di)(di)線緊(jin)鎖(suo)在接(jie)(jie)(jie)線端子上,不得捆綁連接(jie)(jie)(jie)。但煤氣(qi)等(deng)易燃(ran)易爆和的管道(dao)不得使用。或(huo)(huo)者(zhe)現(xian)場(chang)(chang)埋設接(jie)(jie)(jie)地(di)(di)體(ti)。接(jie)(jie)(jie)地(di)(di)體(ti)可(ke)以(yi)(yi)采用角鋼或(huo)(huo)者(zhe)鋼管,水平(ping)或(huo)(huo)者(zhe)豎直埋入大(da)(da)地(di)(di)中作為簡易接(jie)(jie)(jie)地(di)(di)點,接(jie)(jie)(jie)地(di)(di)點應(ying)選擇偏僻(pi)的地(di)(di)方,以(yi)(yi)免行人(ren)或(huo)(huo)者(zhe)車輛破壞接(jie)(jie)(jie)地(di)(di)體(ti)。
我們(men)接(jie)(jie)(jie)地(di)(di)時(shi)(shi)接(jie)(jie)(jie)地(di)(di)電(dian)阻必須(xu)小于4歐姆,以(yi)保(bao)證漏電(dian)流的(de)及時(shi)(shi)泄(xie)放(fang)(fang)。需要注意的(de)是(shi),防(fang)雷(lei)接(jie)(jie)(jie)地(di)(di)端(duan)(duan)在泄(xie)放(fang)(fang)雷(lei)擊(ji)電(dian)流時(shi)(shi)由(you)于大地(di)(di)電(dian)流的(de)擴(kuo)散需要一定時(shi)(shi)間,短時(shi)(shi)間內會(hui)導(dao)致大地(di)(di)電(dian)位升(sheng)高(gao),如果LED顯(xian)(xian)示(shi)屏(ping)接(jie)(jie)(jie)地(di)(di)聯(lian)接(jie)(jie)(jie)至(zhi)防(fang)雷(lei)接(jie)(jie)(jie)地(di)(di)端(duan)(duan),這(zhe)時(shi)(shi)大地(di)(di)電(dian)位比顯(xian)(xian)示(shi)屏(ping)要高(gao),雷(lei)擊(ji)電(dian)流將會(hui)沿順這(zhe)地(di)(di)線(xian)傳遞至(zhi)屏(ping)體(ti),造(zao)成設備損壞。所以(yi)LED顯(xian)(xian)示(shi)屏(ping)這(zhe)種保(bao)護(hu)接(jie)(jie)(jie)地(di)(di)不(bu)得聯(lian)結至(zhi)防(fang)雷(lei)接(jie)(jie)(jie)地(di)(di)端(duan)(duan)上,保(bao)護(hu)接(jie)(jie)(jie)地(di)(di)端(duan)(duan)必須(xu)距(ju)離防(fang)雷(lei)接(jie)(jie)(jie)地(di)(di)端(duan)(duan)20米以(yi)上。防(fang)止地(di)(di)電(dian)位的(de)反擊(ji)。
LED接地注(zhu)意事項總(zong)結:
1、每個(ge)電源(yuan)都必須從接地(di)端子接地(di),并鎖緊(jin);
2、接地電阻不得大(da)于4Ω;
3、地線應為專(zhuan)屬導線,嚴禁和零線聯(lian)接(jie);
4、地線(xian)上不(bu)得安裝空開或熔斷器(qi);
5、地(di)(di)線(xian)和接地(di)(di)端子(zi)都應遠離防雷(lei)接地(di)(di)端20以上;
嚴禁部分(fen)設(she)備采用保護(hu)接(jie)(jie)(jie)地(di)來代(dai)替保護(hu)接(jie)(jie)(jie)零,造成保護(hu)接(jie)(jie)(jie)地(di)和保護(hu)接(jie)(jie)(jie)零混接(jie)(jie)(jie)錯接(jie)(jie)(jie)。當某一(yi)保護(hu)接(jie)(jie)(jie)地(di)設(she)備的(de)(de)絕緣損壞,發生相線(xian)碰(peng)殼(ke)時,零線(xian)出現對地(di)電壓,于是使保護(hu)接(jie)(jie)(jie)零設(she)備的(de)(de)外殼(ke)上就產生了危險(xian)電壓。
因此(ci),在同一母線(xian)供(gong)電的(de)(de)線(xian)路中,保(bao)(bao)護接地和保(bao)(bao)護接零不能混用,即不可把一部分電氣(qi)設備(bei)接零,而將另(ling)一部分電氣(qi)設備(bei)接地。一般市(shi)電都采用接零保(bao)(bao)護,故使用市(shi)電的(de)(de)電氣(qi)設備(bei),應(ying)采取接零保(bao)(bao)護。
4、保護(hu)接(jie)零注意事項
(1)在(zai)(zai)保護(hu)接(jie)(jie)零(ling)(ling)的(de)電(dian)(dian)氣系(xi)統中(zhong)。零(ling)(ling)線(xian)起(qi)著(zhu)至關(guan)重要的(de)作用。一(yi)旦零(ling)(ling)線(xian)斷(duan)開,接(jie)(jie)在(zai)(zai)斷(duan)線(xian)處(chu)后(hou)面的(de)一(yi)段線(xian)路(lu)的(de)電(dian)(dian)氣設(she)(she)備相當于(yu)沒(mei)有(you)了保護(hu)接(jie)(jie)零(ling)(ling)和保護(hu)接(jie)(jie)地(di),若在(zai)(zai)零(ling)(ling)線(xian)斷(duan)處(chu)后(hou)面有(you)電(dian)(dian)氣設(she)(she)備外殼(ke)漏電(dian)(dian)則不(bu)構成(cheng)短路(lu)回路(lu),而(er)使熔體熔斷(duan)。不(bu)但(dan)該臺設(she)(she)備外殼(ke)帶有(you)電(dian)(dian)壓(ya),而(er)且使得斷(duan)線(xian)處(chu)后(hou)面的(de)所(suo)有(you)設(she)(she)備的(de)外殼(ke)都存在(zai)(zai)接(jie)(jie)近電(dian)(dian)源相電(dian)(dian)壓(ya)的(de)對地(di)電(dian)(dian)壓(ya),觸電(dian)(dian)危(wei)險性將擴大。
所有電氣設備接(jie)保護接(jie)零線(xian)均應以(yi)并聯(lian)方式接(jie)在電源零線(xian)上,不允許(xu)串聯(lian),并用螺栓壓緊,牢固可靠(kao),接(jie)觸良(liang)好。在零線(xian)上,禁止安裝保險和(he)單獨開關。在特殊的環境(jing)中,零線(xian)做防腐處理也(ye)就不言而(er)喻(yu)了。
(2)中(zhong)性(xing)點(dian)(dian)不(bu)(bu)接(jie)地(di)的(de)三(san)相四線(xian)制配電(dian)系(xi)統中(zhong),不(bu)(bu)允許用(yong)保護接(jie)零(ling),只能用(yong)保護接(jie)地(di)。系(xi)統中(zhong)任意一相發生接(jie)地(di),整(zheng)個系(xi)統仍照常運行,但大地(di)與接(jie)地(di)線(xian)等電(dian)位,則(ze)接(jie)在零(ling)線(xian)上的(de)用(yong)電(dian)設備外殼(ke)對(dui)地(di)電(dian)壓降(jiang)等于接(jie)地(di)的(de)相線(xian)從接(jie)地(di)點(dian)(dian)到中(zhong)性(xing)點(dian)(dian)的(de)電(dian)壓值,是十分危(wei)險的(de)。
(3)在采用保護接(jie)零系統中還要在電源(yuan)中性點(dian)進行工作(zuo)接(jie)地和零線(xian)一定間隔(ge)距離及終端進行重(zhong)復接(jie)地。在中性點(dian)接(jie)地的(de)系統中除(chu)將變(bian)壓器中性點(dian)做接(jie)地外,沿零線(xian)走向的(de)一處或者(zhe)多處再次將零線(xian)接(jie)地叫重(zhong)復接(jie)地。
其(qi)作用是(shi)當(dang)電(dian)(dian)氣設(she)備外殼漏(lou)電(dian)(dian)時可(ke)以降(jiang)低(di)對地(di)電(dian)(dian)壓(ya)。當(dang)零線(xian)斷(duan)時也(ye)減輕觸電(dian)(dian)危險(xian)(xian)。當(dang)電(dian)(dian)氣設(she)備外殼漏(lou)電(dian)(dian)時,經相線(xian)、零線(xian)構成(cheng)短路(lu)回(hui)路(lu),短路(lu)電(dian)(dian)流(liu)將熔斷(duan)保險(xian)(xian)。設(she)備外殼隨之斷(duan)電(dian)(dian),不(bu)會出現(xian)觸電(dian)(dian)危險(xian)(xian)。但是(shi)保險(xian)(xian)熔斷(duan)之前(qian)設(she)備帶電(dian)(dian),對人(ren)身還是(shi)有危險(xian)(xian)的。若在接近設(she)備處再加接地(di)裝置,即實(shi)行重復(fu)接地(di),帶電(dian)(dian)設(she)備的導體部分(fen)對地(di)電(dian)(dian)壓(ya)降(jiang)低(di)。
(4)保護(hu)接零必須有可靠靈敏(min)的短路(lu)保護(hu)裝置(zhi)來配合,因此,熔斷(duan)絲嚴禁(jin)用(yong)銅絲等金屬材料來代替符合要求的金屬熔斷(duan)絲,否則接零保護(hu)將失去其保護(hu)作用(yong)。
以上都是鄭州(zhou)LED顯示(shi)屏小(xiao)編(bian)為大家(jia)講解的(de)相關內容,希望可以幫助到(dao)大家(jia)!