由于地鐵車輛(liang)的機構特點(dian)決定了車輛(liang)設備(bei)內部布局十分密集，進而使得車輛(liang)內部的電(dian)(dian)磁環境變得更為復雜，考慮到抑制電(dian)(dian)磁干(gan)擾(rao)，必須將地鐵車輛(liang)上(shang)的電(dian)(dian)氣(qi)、電(dian)(dian)子設備(bei)進行接地。如(ru)何進行接地呢？針對(dui)該(gai)問題(ti)，鈞和電(dian)(dian)子做如(ru)下分享：

一是，接(jie)地的作用

接(jie)(jie)地(di)是(shi)為了防止電(dian)(dian)(dian)(dian)器元件受到過(guo)(guo)電(dian)(dian)(dian)(dian)流損傷而將(jiang)電(dian)(dian)(dian)(dian)流導(dao)入大(da)地(di)的(de)一種(zhong)電(dian)(dian)(dian)(dian)氣連接(jie)(jie)方式。對于低壓(ya)弱(ruo)電(dian)(dian)(dian)(dian)流的(de)信號(hao)傳輸電(dian)(dian)(dian)(dian)纜來說，外部(bu)的(de)電(dian)(dian)(dian)(dian)磁(ci)(ci)干擾(rao)會對傳輸的(de)電(dian)(dian)(dian)(dian)氣信號(hao)產(chan)生影響，在電(dian)(dian)(dian)(dian)纜外部(bu)加裝(zhuang)金屬屏(ping)蔽(bi)網(wang)并可(ke)靠接(jie)(jie)地(di)，可(ke)以有效地(di)避免此類(lei)電(dian)(dian)(dian)(dian)磁(ci)(ci)干擾(rao)。在地(di)鐵(tie)車(che)輛(liang)方面，“地(di)”就是(shi)車(che)體(ti)外殼的(de)金屬結構，將(jiang)車(che)輛(liang)電(dian)(dian)(dian)(dian)器通(tong)過(guo)(guo)接(jie)(jie)地(di)線和車(che)體(ti)連接(jie)(jie)，并通(tong)過(guo)(guo)特定的(de)接(jie)(jie)地(di)裝(zhuang)置將(jiang)車(che)體(ti)與轉向架連接(jie)(jie)，最終通(tong)過(guo)(guo)鋼軌(gui)引入大(da)地(di)。

二是，地(di)鐵車(che)輛(liang)設(she)備(bei)接(jie)地(di)的(de)方式

1.單點接地

單(dan)點(dian)(dian)接(jie)地是為(wei)許多在一起的電(dian)路提(ti)供公共電(dian)勢參考點(dian)(dian)的方法，即把整個電(dian)路系統中(zhong)的一個結構點(dian)(dian)作(zuo)為(wei)接(jie)地參考點(dian)(dian)，所有對地連接(jie)都接(jie)在這一點(dian)(dian)。工作(zuo)頻率(lv)低(di)于1MHz經常采用單(dan)點(dian)(dian)接(jie)地。單(dan)點(dian)(dian)接(jie)地又可分為(wei)串聯(lian)(lian)單(dan)點(dian)(dian)接(jie)地和(he)并聯(lian)(lian)單(dan)點(dian)(dian)接(jie)地。

2.多點接(jie)地

設(she)備(bei)內電路都以機(ji)殼(ke)(ke)為(wei)(wei)參考(kao)點(dian)，而各個設(she)備(bei)的(de)機(ji)殼(ke)(ke)又(you)都以地(di)(di)為(wei)(wei)參考(kao)點(dian)。多點(dian)接(jie)地(di)(di)容易產生公共阻(zu)抗耦合問題。一般在工作(zuo)頻(pin)率(lv)高于10MHz時(shi)采(cai)用多點(dian)接(jie)地(di)(di)。由(you)于接(jie)地(di)(di)線感(gan)抗與頻(pin)率(lv)和長度成正比，工作(zuo)頻(pin)率(lv)高時(shi)會增加共地(di)(di)阻(zu)抗，增大電磁(ci)干擾，因此(ci)要求(qiu)接(jie)地(di)(di)線盡量(liang)短，也就是常(chang)說的(de)就近接(jie)地(di)(di)。多點(dian)接(jie)地(di)(di)方(fang)式的(de)基本(ben)方(fang)法(fa)是車體(ti)同(tong)時(shi)作(zuo)為(wei)(wei)安(an)全接(jie)地(di)(di)、等(deng)電勢(shi)接(jie)地(di)(di)、回流地(di)(di)和屏(ping)蔽(bi)接(jie)地(di)(di)。它相對常(chang)規的(de)單點(dian)接(jie)地(di)(di)而言，對車輛更(geng)為(wei)(wei)簡單有效。

3.混合接地

混(hun)合接(jie)地(di)結合了單點(dian)(dian)接(jie)地(di)和多(duo)點(dian)(dian)接(jie)地(di)的特(te)性。

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