電機用了變(bian)頻器出現漏電是什么情(qing)況?原來是這樣的

　　一、變頻器輸出是以PWM(脈寬調制，類似高(gao)速開關)方式控制，因(yin)此會(hui)發(fa)生高(gao)頻率的漏電電流(liu)。

　　變頻器(qi)、前級(ji)供電(dian)變壓器(qi)、電(dian)動(dong)機三個(ge)傳動(dong)設備的PE點 要連在一起后(hou)，再統一去接地。

　　變頻(pin)器是高頻(pin)方波電(dian)(dian)壓輸(shu)出，由于在電(dian)(dian)機內部(bu)線圈與電(dian)(dian)機外殼之間有(you)等效電(dian)(dian)容存(cun)在，從(cong)而(er)產生泄漏電(dian)(dian)流。如果不(bu)接地或接地不(bu)良，就會有(you)漏電(dian)(dian)現象。

　　影響漏電電流大(da)小之因素有：

　　(1)電(dian)(dian)纜(lan)線(xian)的漏(lou)(lou)電(dian)(dian)電(dian)(dian)流(liu)(liu)漏(lou)(lou)電(dian)(dian)斷路(lu)開關、濾波器的電(dian)(dian)纜(lan)線(xian)長(chang)之(zhi)漏(lou)(lou)電(dian)(dian)電(dian)(dian)流(liu)(liu)。 變頻(pin)器、馬達的電(dian)(dian)纜(lan)線(xian)長(chang)之(zhi)漏(lou)(lou)電(dian)(dian)電(dian)(dian)流(liu)(liu)。

　　(2)濾波(bo)器的漏(lou)電電流 (包含變頻器在內(nei))。

　　(3)馬(ma)達(da)的漏電(dian)電(dian)流。

　　有(you)的(de)現場使用變(bian)頻器(qi)控(kong)制電(dian)(dian)(dian)機，會出現漏電(dian)(dian)(dian)問(wen)題，漏電(dian)(dian)(dian)電(dian)(dian)(dian)壓有(you)幾十伏(fu)到二百(bai)伏(fu)電(dian)(dian)(dian)壓不等。針對這(zhe)個問(wen)題，特對此種現象(xiang)產(chan)生(sheng)的(de)原(yuan)因進(jin)行分析如下：

　　二、根據變(bian)頻器(qi)控(kong)制(zhi)電(dian)(dian)(dian)機(ji)運(yun)行的功能框圖，三相(xiang)電(dian)(dian)(dian)源(yuan)經(jing)過(guo)變(bian)頻器(qi)整(zheng)流橋整(zheng)流之(zhi)后，經(jing)電(dian)(dian)(dian)容濾波(bo)送到逆變(bian)橋(IGBT)，再經(jing)過(guo)逆變(bian)橋輸(shu)出頻率、電(dian)(dian)(dian)壓可調(diao)的三 相(xiang)交流電(dian)(dian)(dian)去控(kong)制(zhi)電(dian)(dian)(dian)機(ji)的運(yun)行。

　　三(san)相(xiang)互差120度(du)的(de)交流(liu)電(dian)在(zai)電(dian)動機的(de)三(san)相(xiang)定子(zi)(zi)線(xian)圈繞組(zu)里流(liu)過，產生旋(xuan)(xuan)(xuan)轉(zhuan)磁(ci)場，使(shi)電(dian)動機的(de)轉(zhuan)子(zi)(zi)在(zai)定子(zi)(zi)繞組(zu)旋(xuan)(xuan)(xuan)轉(zhuan)磁(ci)場的(de)作用下自(zi)動旋(xuan)(xuan)(xuan)轉(zhuan)起來(lai)。

　　電(dian)(dian)(dian)(dian)(dian)(dian)(dian)動(dong)(dong)機(ji)(ji)(ji)的(de)三相定(ding)子繞(rao)組流(liu)過(guo)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)之后產生(sheng)了旋轉磁場，而根據(ju)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)磁感(gan)(gan)應(ying)的(de)原理，電(dian)(dian)(dian)(dian)(dian)(dian)(dian)動(dong)(dong)機(ji)(ji)(ji)的(de)外(wai)殼就(jiu)(jiu)(jiu)(jiu)會產生(sheng)感(gan)(gan)應(ying)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)動(dong)(dong)勢(shi)。此感(gan)(gan)應(ying)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)動(dong)(dong)勢(shi)的(de)大小(xiao)，就(jiu)(jiu)(jiu)(jiu)取決于變(bian)頻(pin)器IGBT的(de)開(kai)(kai)關(guan)(guan)頻(pin)率(lv)(lv)的(de)大小(xiao)和(he)C×DV/DT(與IGBT的(de)開(kai)(kai)關(guan)(guan)的(de)速度(du)有關(guan)(guan))。如果這(zhe)個(ge)感(gan)(gan)應(ying)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)動(dong)(dong)勢(shi)較大，那(nei)么(me)人觸(chu)摸到就(jiu)(jiu)(jiu)(jiu)會感(gan)(gan)覺被電(dian)(dian)(dian)(dian)(dian)(dian)(dian)擊一樣。理論上IGBT的(de)開(kai)(kai)關(guan)(guan)頻(pin)率(lv)(lv)越(yue)(yue)高，電(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)(ji)外(wai)殼的(de)感(gan)(gan)應(ying)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)動(dong)(dong)勢(shi)的(de) 值(即感(gan)(gan)應(ying)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓)就(jiu)(jiu)(jiu)(jiu)越(yue)(yue)高，而變(bian)頻(pin)器對(dui)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)(ji)的(de)控制精度(du)和(he)動(dong)(dong)態響應(ying)也就(jiu)(jiu)(jiu)(jiu)越(yue)(yue)高，人體觸(chu)摸之后被電(dian)(dian)(dian)(dian)(dian)(dian)(dian)的(de)感(gan)(gan)覺就(jiu)(jiu)(jiu)(jiu)越(yue)(yue)大;反(fan)之，IGBT的(de)開(kai)(kai)關(guan)(guan)頻(pin)率(lv)(lv)越(yue)(yue)低，電(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)(ji)外(wai)殼的(de)感(gan)(gan)應(ying)動(dong)(dong)勢(shi)的(de) 值(感(gan)(gan)應(ying)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓)就(jiu)(jiu)(jiu)(jiu)越(yue)(yue)低，而從體觸(chu)摸到之后被電(dian)(dian)(dian)(dian)(dian)(dian)(dian)的(de)感(gan)(gan)覺就(jiu)(jiu)(jiu)(jiu)越(yue)(yue)小(xiao)。

　　由于異步電(dian)(dian)動機運轉，電(dian)(dian)機外殼都會有感(gan)應(ying)電(dian)(dian)壓(即所(suo)(suo)謂的(de)漏電(dian)(dian))，所(suo)(suo)以(yi)(yi)(yi)，電(dian)(dian)機制造(zao)廠才(cai)會在(zai)電(dian)(dian)動機出廠的(de)時(shi)候，在(zai)其(qi)接(jie)線(xian)盒里(li)面安上接(jie)地端子，方(fang)便用戶在(zai)應(ying)用時(shi)連接(jie)大(da)地以(yi)(yi)(yi) 其(qi)感(gan)應(ying)電(dian)(dian)動勢(shi)(即 感(gan)應(ying)漏電(dian)(dian)電(dian)(dian)壓)，以(yi)(yi)(yi)解決(jue)人體接(jie)觸電(dian)(dian)動機時(shi)被電(dian)(dian)的(de)感(gan)覺。

　　工頻(pin)(pin)(pin)運行電(dian)(dian)(dian)機(ji)(ji)時，工頻(pin)(pin)(pin)的(de)開關(guan)(guan)頻(pin)(pin)(pin)率約為50HZ，很低，所(suo)以(yi)一般情(qing)況下幾(ji)乎不會有(you)漏電(dian)(dian)(dian)的(de)感覺(除非電(dian)(dian)(dian)機(ji)(ji)絕緣很差)。而(er)變(bian)頻(pin)(pin)(pin)器控(kong)制時，由于其開關(guan)(guan)頻(pin)(pin)(pin)率都比工頻(pin)(pin)(pin)頻(pin)(pin)(pin)率高得多(duo)，所(suo)以(yi)變(bian)頻(pin)(pin)(pin)器在控(kong)制電(dian)(dian)(dian)動(dong)機(ji)(ji)轉動(dong)時，電(dian)(dian)(dian)機(ji)(ji)外殼(ke)就會有(you)漏電(dian)(dian)(dian)的(de)感覺。