1、漏電問題產生的原因

在有的(de)現場使用(yong)變(bian)頻(pin)器控制電機(ji)會出現漏電問題，漏電電壓有幾(ji)十(shi)伏到200伏不等(deng)，在這里(li)針對此故障的(de)原因進行(xing)理論的(de)分析和(he)說(shuo)明如下(xia)。

根(gen)據變(bian)頻器控制電機運行的(de)功(gong)能圖(tu)（圖(tu)1）

三相電(dian)(dian)(dian)經(jing)過整流經(jing)濾(lv)波電(dian)(dian)(dian)容供電(dian)(dian)(dian)給逆變橋（IGBT），再經(jing)逆變器輸(shu)出頻率(lv)、電(dian)(dian)(dian)壓可(ke)調的三相電(dian)(dian)(dian)去控(kong)制電(dian)(dian)(dian)機的運(yun)行(xing)。

我們都知道電(dian)(dian)(dian)(dian)(dian)(dian)動(dong)(dong)(dong)機(ji)的(de)(de)(de)(de)(de)(de)三相(xiang)定子繞組流過(guo)電(dian)(dian)(dian)(dian)(dian)(dian)流產生(sheng)(sheng)旋(xuan)轉磁場，根據磁電(dian)(dian)(dian)(dian)(dian)(dian)感(gan)(gan)應(ying)(ying)的(de)(de)(de)(de)(de)(de)原(yuan)理，電(dian)(dian)(dian)(dian)(dian)(dian)動(dong)(dong)(dong)機(ji)的(de)(de)(de)(de)(de)(de)外殼就(jiu)(jiu)會(hui)(hui)(hui)產生(sheng)(sheng)感(gan)(gan)應(ying)(ying)電(dian)(dian)(dian)(dian)(dian)(dian)動(dong)(dong)(dong)勢(shi)，此(ci)電(dian)(dian)(dian)(dian)(dian)(dian)動(dong)(dong)(dong)勢(shi)的(de)(de)(de)(de)(de)(de)大小(xiao)(xiao)就(jiu)(jiu)取(qu)決于(yu)變(bian)頻(pin)(pin)(pin)器IGBT的(de)(de)(de)(de)(de)(de)開(kai)(kai)(kai)關(guan)頻(pin)(pin)(pin)率(lv)(lv)(lv)的(de)(de)(de)(de)(de)(de)大小(xiao)(xiao)，由于(yu)高(gao)(gao)性(xing)能的(de)(de)(de)(de)(de)(de)控(kong)制(zhi)要求高(gao)(gao)的(de)(de)(de)(de)(de)(de)開(kai)(kai)(kai)關(guan)頻(pin)(pin)(pin)率(lv)(lv)(lv)，其(qi)開(kai)(kai)(kai)關(guan)速(su)(su)度(du)很(hen)快，則DV/DT偏大，同時這(zhe)個感(gan)(gan)應(ying)(ying)電(dian)(dian)(dian)(dian)(dian)(dian)動(dong)(dong)(dong)勢(shi)就(jiu)(jiu)偏大，人觸(chu)摸上(shang)(shang)就(jiu)(jiu)有電(dian)(dian)(dian)(dian)(dian)(dian)擊(ji)的(de)(de)(de)(de)(de)(de)感(gan)(gan)覺(jue)。理論上(shang)(shang)IGBT的(de)(de)(de)(de)(de)(de)開(kai)(kai)(kai)關(guan)速(su)(su)度(du)越(yue)快，電(dian)(dian)(dian)(dian)(dian)(dian)機(ji)外殼上(shang)(shang)的(de)(de)(de)(de)(de)(de)感(gan)(gan)應(ying)(ying)電(dian)(dian)(dian)(dian)(dian)(dian)動(dong)(dong)(dong)勢(shi)就(jiu)(jiu)越(yue)高(gao)(gao)，而變(bian)頻(pin)(pin)(pin)器對電(dian)(dian)(dian)(dian)(dian)(dian)機(ji)的(de)(de)(de)(de)(de)(de)控(kong)制(zhi)精(jing)度(du)和(he)響(xiang)應(ying)(ying)就(jiu)(jiu)越(yue)高(gao)(gao)，人觸(chu)摸之后被電(dian)(dian)(dian)(dian)(dian)(dian)的(de)(de)(de)(de)(de)(de)感(gan)(gan)覺(jue)就(jiu)(jiu)越(yue)高(gao)(gao)，反之，IGBT的(de)(de)(de)(de)(de)(de)開(kai)(kai)(kai)關(guan)頻(pin)(pin)(pin)率(lv)(lv)(lv)慢，感(gan)(gan)應(ying)(ying)電(dian)(dian)(dian)(dian)(dian)(dian)就(jiu)(jiu)小(xiao)(xiao)，人觸(chu)摸的(de)(de)(de)(de)(de)(de)感(gan)(gan)覺(jue)就(jiu)(jiu)小(xiao)(xiao)，所以國內(nei)的(de)(de)(de)(de)(de)(de)低(di)端(duan)變(bian)頻(pin)(pin)(pin)器設計的(de)(de)(de)(de)(de)(de)開(kai)(kai)(kai)關(guan)頻(pin)(pin)(pin)率(lv)(lv)(lv)偏低(di)，控(kong)制(zhi)電(dian)(dian)(dian)(dian)(dian)(dian)機(ji)后感(gan)(gan)應(ying)(ying)電(dian)(dian)(dian)(dian)(dian)(dian)小(xiao)(xiao)，人摸上(shang)(shang)沒啥感(gan)(gan)覺(jue)，但其(qi)控(kong)制(zhi)性(xing)較(jiao)(jiao)差(cha)，動(dong)(dong)(dong)態響(xiang)應(ying)(ying)較(jiao)(jiao)慢。奧圣變(bian)頻(pin)(pin)(pin)器性(xing)能和(he)動(dong)(dong)(dong)態響(xiang)應(ying)(ying)都較(jiao)(jiao)好，因而我司的(de)(de)(de)(de)(de)(de)IGBT的(de)(de)(de)(de)(de)(de)開(kai)(kai)(kai)關(guan)頻(pin)(pin)(pin)率(lv)(lv)(lv)和(he)速(su)(su)度(du)都較(jiao)(jiao)高(gao)(gao)，感(gan)(gan)應(ying)(ying)電(dian)(dian)(dian)(dian)(dian)(dian)動(dong)(dong)(dong)勢(shi)相(xiang)應(ying)(ying)會(hui)(hui)(hui)大些。因為工頻(pin)(pin)(pin)運行電(dian)(dian)(dian)(dian)(dian)(dian)機(ji)是的(de)(de)(de)(de)(de)(de)頻(pin)(pin)(pin)率(lv)(lv)(lv)只有50HZ，所以一(yi)邊情況下不會(hui)(hui)(hui)有漏(lou)(lou)電(dian)(dian)(dian)(dian)(dian)(dian)的(de)(de)(de)(de)(de)(de)感(gan)(gan)覺(jue)，而變(bian)頻(pin)(pin)(pin)控(kong)制(zhi)時，開(kai)(kai)(kai)關(guan)頻(pin)(pin)(pin)率(lv)(lv)(lv)很(hen)高(gao)(gao)，電(dian)(dian)(dian)(dian)(dian)(dian)機(ji)外殼就(jiu)(jiu)會(hui)(hui)(hui)有漏(lou)(lou)電(dian)(dian)(dian)(dian)(dian)(dian)的(de)(de)(de)(de)(de)(de)感(gan)(gan)覺(jue)。

2、漏電問題的解決方案

為(wei)了避免(mian)這(zhe)(zhe)個(ge)問題的(de)(de)發生(sheng)，在硬(ying)件設計的(de)(de)時候，就加入了感(gan)應(ying)電(dian)(dian)(dian)(dian)浪(lang)涌(yong)濾波(bo)器(qi)(qi)電(dian)(dian)(dian)(dian)路（其等效電(dian)(dian)(dian)(dian)路如圖1所示），并(bing)將浪(lang)涌(yong)濾波(bo)器(qi)(qi)的(de)(de)接(jie)(jie)(jie)地(di)端于變(bian)(bian)頻(pin)器(qi)(qi)的(de)(de)外殼相(xiang)連(lian)，同(tong)(tong)時在變(bian)(bian)頻(pin)器(qi)(qi)的(de)(de)配線(xian)說(shuo)明中，要求(qiu)將電(dian)(dian)(dian)(dian)機(ji)(ji)(ji)的(de)(de)接(jie)(jie)(jie)地(di)端同(tong)(tong)變(bian)(bian)頻(pin)器(qi)(qi)的(de)(de)接(jie)(jie)(jie)地(di)B相(xiang)連(lian)，將輸入電(dian)(dian)(dian)(dian)源(yuan)(yuan)的(de)(de)地(di)（大(da)地(di)）同(tong)(tong)變(bian)(bian)頻(pin)器(qi)(qi)的(de)(de)接(jie)(jie)(jie)地(di)A相(xiang)連(lian)，從而使電(dian)(dian)(dian)(dian)機(ji)(ji)(ji)的(de)(de)感(gan)應(ying)電(dian)(dian)(dian)(dian)通過電(dian)(dian)(dian)(dian)機(ji)(ji)(ji)與變(bian)(bian)頻(pin)器(qi)(qi)的(de)(de)接(jie)(jie)(jie)地(di)和變(bian)(bian)頻(pin)器(qi)(qi)與電(dian)(dian)(dian)(dian)源(yuan)(yuan)的(de)(de)接(jie)(jie)(jie)地(di)線(xian)形成回路，使電(dian)(dian)(dian)(dian)機(ji)(ji)(ji)的(de)(de)地(di)變(bian)(bian)頻(pin)器(qi)(qi)的(de)(de)地(di)和電(dian)(dian)(dian)(dian)源(yuan)(yuan)的(de)(de)地(di)在同(tong)(tong)一電(dian)(dian)(dian)(dian)位上，他們之間的(de)(de)電(dian)(dian)(dian)(dian)位差是為(wei)0伏(fu)電(dian)(dian)(dian)(dian)壓，這(zhe)(zhe)樣(yang)人站在大(da)地(di)上面(mian)接(jie)(jie)(jie)觸到電(dian)(dian)(dian)(dian)機(ji)(ji)(ji)的(de)(de)外殼、設備(bei)的(de)(de)機(ji)(ji)(ji)架、變(bian)(bian)頻(pin)器(qi)(qi)的(de)(de)外殼就不會有(you)被電(dian)(dian)(dian)(dian)的(de)(de)感(gan)覺了。

但是有(you)些工(gong)廠內為(wei)了配線方便，高壓(ya)配電房內沒有(you)把地(di)線拉入車(che)間，甚至錯誤(wu)的(de)(de)認為(wei)大(da)地(di)就是地(di)線，這(zhe)種想(xiang)(xiang)法是錯誤(wu)的(de)(de)，大(da)家(jia)不(bu)妨想(xiang)(xiang)一想(xiang)(xiang)，如果大(da)地(di)可以當地(di)線，那我們日常生活中(zhong)何(he)必拉N線盒地(di)線呢？發電站里(li)的(de)(de)N線也是和(he)地(di)線連在一起(qi)的(de)(de)啊？我們不(bu)用(yong)拉N線盒地(di)線不(bu)是省很(hen)多電線嗎？為(wei)啥浪費人力、物力、時間呢？然而(er)現實中(zhong)有(you)很(hen)多工(gong)廠沒有(you)拉電源地(di)線的(de)(de)，設(she)備沒法找到接(jie)地(di)點，而(er)電機在使用(yong)中(zhong)卻有(you)感應漏電的(de)(de)情況，遇(yu)到這(zhe)種情況，我們提供兩種方案：

方(fang)案1：將電機(ji)的(de)接(jie)(jie)地端、機(ji)架(jia)外殼、變頻器的(de)接(jie)(jie)地端接(jie)(jie)在一起

（圖3）

電(dian)(dian)機、變(bian)頻(pin)器、機架(jia)三個(ge)電(dian)(dian)線連在一起之后，使(shi)他(ta)們處于(yu)同一電(dian)(dian)位，并經過變(bian)頻(pin)器內部的(de)浪(lang)(lang)涌吸收、泄放(fang)，使(shi)感(gan)(gan)應電(dian)(dian)壓大大減小，這樣(yang)不至(zhi)于(yu)讓人又觸電(dian)(dian)的(de)感(gan)(gan)覺，也(ye)就(jiu)是說(shuo)沒有地線也(ye)沒有關系，只要(yao)就(jiu)幾(ji)個(ge)的(de)地連在一起就(jiu)好了，這樣(yang)變(bian)頻(pin)器內部的(de)浪(lang)(lang)涌濾(lv)波(bo)器才起作用(yong)到作用(yong)。

方(fang)案(an)2：一(yi)(yi)般情況下(xia)經過方(fang)案(an)1的(de)處(chu)理(li)，不至(zhi)于(yu)會有電(dian)(dian)人的(de)現(xian)象，但由于(yu)特殊的(de)原因(yin)，感(gan)(gan)應電(dian)(dian)壓(ya)還是比較(jiao)高，還可以(yi)電(dian)(dian)人，那就(jiu)在方(fang)案(an)1的(de)前提下(xia)再在變(bian)頻器(qi)的(de)輸入電(dian)(dian)源端增加一(yi)(yi)個感(gan)(gan)應電(dian)(dian)浪涌(yong)濾波(bo)器(qi)。

（圖4）

并(bing)將感應(ying)電(dian)(dian)(dian)浪(lang)涌濾(lv)波器(qi)(qi)的(de)(de)(de)(de)地(di)(di)與電(dian)(dian)(dian)動(dong)機的(de)(de)(de)(de)地(di)(di)、變(bian)頻器(qi)(qi)的(de)(de)(de)(de)地(di)(di)接在(zai)一(yi)起（如圖4中的(de)(de)(de)(de)紅色線(xian)所示）讓感應(ying)電(dian)(dian)(dian)浪(lang)涌濾(lv)波器(qi)(qi)再一(yi)次對電(dian)(dian)(dian)機的(de)(de)(de)(de)感應(ying)電(dian)(dian)(dian)進行吸收和泄放，進一(yi)步(bu)減小感應(ying)電(dian)(dian)(dian)壓，達到(dao)防止(zhi)漏電(dian)(dian)(dian)電(dian)(dian)(dian)人的(de)(de)(de)(de)目前的(de)(de)(de)(de)。增(zeng)加(jia)的(de)(de)(de)(de)感應(ying)電(dian)(dian)(dian)浪(lang)涌濾(lv)波器(qi)(qi)的(de)(de)(de)(de)電(dian)(dian)(dian)路(lu)原理與變(bian)頻器(qi)(qi)內(nei)部(bu)的(de)(de)(de)(de)浪(lang)涌濾(lv)波電(dian)(dian)(dian)路(lu)是一(yi)樣的(de)(de)(de)(de)，是由于體積太(tai)大，沒法設(she)計安裝(zhuang)在(zai)變(bian)頻器(qi)(qi)內(nei)部(bu)電(dian)(dian)(dian)路(lu)里面，因此做成(cheng)外接方式(shi)。

我們(men)曾經過(guo)大(da)量的實(shi)驗證明，通過(guo)方(fang)案二(er)這種接(jie)(jie)法的現(xian)場整改，在沒有(you)接(jie)(jie)電(dian)源(yuan)的地(di)線(xian)的應用(yong)(yong)場合下，都能將電(dian)動機(ji)運轉產生的感(gan)(gan)應電(dian)壓減小(xiao)到20V以下，確保現(xian)場操作人員的安(an)全(quan)，不(bu)(bu)會再有(you)被漏電(dian)電(dian)人的感(gan)(gan)覺。但是，方(fang)案二(er)中如果接(jie)(jie)有(you)電(dian)源(yuan)線(xian)的地(di)線(xian)，那么也就不(bu)(bu)用(yong)(yong)外接(jie)(jie)感(gan)(gan)應電(dian)浪涌濾波器都可以了。

另外(wai)，如(ru)果現場(chang)是(shi)有多(duo)臺變頻(pin)器(qi)(qi)控制電(dian)(dian)動機(ji)運轉時，且不(bu)方便安(an)裝多(duo)個(ge)感應(ying)(ying)電(dian)(dian)浪(lang)(lang)(lang)涌(yong)濾波(bo)器(qi)(qi)的(de)(de)，并(bing)不(bu)一(yi)(yi)定是(shi)要求每臺變頻(pin)器(qi)(qi)都配一(yi)(yi)下(xia)感應(ying)(ying)電(dian)(dian)浪(lang)(lang)(lang)涌(yong)濾波(bo)器(qi)(qi)，也可以只(zhi)接(jie)(jie)一(yi)(yi)個(ge)或(huo)兩個(ge)感應(ying)(ying)電(dian)(dian)浪(lang)(lang)(lang)涌(yong)濾波(bo)器(qi)(qi)，并(bing)將濾波(bo)器(qi)(qi)的(de)(de)接(jie)(jie)地端(duan)與現場(chang)幾臺變頻(pin)器(qi)(qi)的(de)(de)接(jie)(jie)地端(duan)、現場(chang)電(dian)(dian)動機(ji)的(de)(de)接(jie)(jie)地端(duan)、設備(bei)機(ji)架接(jie)(jie)在一(yi)(yi)起(qi)，如(ru)圖5所示(shi)：由于每臺變頻(pin)器(qi)(qi)內部都有感應(ying)(ying)電(dian)(dian)浪(lang)(lang)(lang)涌(yong)濾波(bo)器(qi)(qi)電(dian)(dian)路，但如(ru)果電(dian)(dian)機(ji)的(de)(de)接(jie)(jie)地線(xian)沒有接(jie)(jie)回(hui)到變頻(pin)器(qi)(qi)的(de)(de)接(jie)(jie)地端(duan)子去(qu)的(de)(de)話，感應(ying)(ying)電(dian)(dian)浪(lang)(lang)(lang)涌(yong)濾波(bo)器(qi)(qi)也就不(bu)起(qi)作(zuo)用(yong)了，所以現場(chang)應(ying)(ying)用(yong)中電(dian)(dian)動機(ji)的(de)(de)接(jie)(jie)地端(duan)一(yi)(yi)定要與變頻(pin)器(qi)(qi)的(de)(de)接(jie)(jie)地端(duan)接(jie)(jie)到一(yi)(yi)起(qi)。

當然有(you)(you)(you)些設備在某些場合(he)電(dian)(dian)(dian)機(ji)不(bu)(bu)(bu)接地(di)(di)線(xian)也不(bu)(bu)(bu)會有(you)(you)(you)漏電(dian)(dian)(dian)的(de)(de)(de)感覺，這與(yu)本文前(qian)面(mian)所說(shuo)的(de)(de)(de)“大地(di)(di)雖(sui)然也是屬(shu)于導(dao)體，但(dan)大地(di)(di)畢竟是有(you)(you)(you)阻值的(de)(de)(de)，而(er)且根據不(bu)(bu)(bu)同的(de)(de)(de)土(tu)地(di)(di)的(de)(de)(de)土(tu)壤成(cheng)份，阻值也大小不(bu)(bu)(bu)一(yi)”原理是一(yi)樣的(de)(de)(de)。但(dan)是按照正確的(de)(de)(de)用(yong)電(dian)(dian)(dian)安全規范(fan)，是要求電(dian)(dian)(dian)機(ji)良(liang)好(hao)接地(di)(di)的(de)(de)(de)，但(dan)條(tiao)件不(bu)(bu)(bu)允許（如沒有(you)(you)(you)電(dian)(dian)(dian)源接地(di)(di)端）的(de)(de)(de)，電(dian)(dian)(dian)動機(ji)的(de)(de)(de)地(di)(di)、電(dian)(dian)(dian)柜(ju)外(wai)殼與(yu)變頻器的(de)(de)(de)地(di)(di)總可以接在一(yi)起(qi)的(de)(de)(de)。