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最近在(zai)一個(ge)舊的(de)(de)廠房里安裝設備，現場變頻器一關(guan)(guan)閉維修(xiu)開關(guan)(guan)，配電(dian)箱里的(de)(de)塑殼(ke)就跳閘。老廠房120A的(de)(de)塑殼(ke)，自帶100ma的(de)(de)漏電(dian)保護，也是比較煩人(ren)，只能(neng)通過進線端引電(dian)。

在生活與生產中，經常要用(yong)(yong)(yong)(yong)到漏(lou)電(dian)開關。但變頻器(qi)有(you)些時(shi)候(hou)用(yong)(yong)(yong)(yong)的不多。大(da)部分(fen)廠家(jia)在車間安裝開關時(shi)，經常采用(yong)(yong)(yong)(yong)漏(lou)電(dian)開關作為總開關。當采用(yong)(yong)(yong)(yong)變頻控制(zhi)時(shi)，問題就出(chu)來了，漏(lou)電(dian)開關用(yong)(yong)(yong)(yong)一(yi)點時(shi)間后，總是跳閘。

在安裝有變頻器(qi)的機器(qi)的時候，要(yao)去掉漏電或者(zhe)另(ling)外單獨(du)采(cai)用塑殼(ke)式斷路器(qi)，免(mian)得開(kai)關(guan)跳閘。引起誤(wu)動作!

使用(yong)(yong)(yong)(yong)變頻(pin)器不能(neng)選用(yong)(yong)(yong)(yong)漏電(dian)(dian)(dian)電(dian)(dian)(dian)流(liu)是30MA的漏電(dian)(dian)(dian)開(kai)關，漏電(dian)(dian)(dian)開(kai)關不能(neng)作為保護人身安(an)全(quan)作用(yong)(yong)(yong)(yong)，主要(yao)原因就(jiu)是變頻(pin)器存在漏電(dian)(dian)(dian)流(liu)，會導致變頻(pin)器誤動作。如(ru)果一定要(yao)安(an)裝(zhuang)漏電(dian)(dian)(dian)開(kai)關，選用(yong)(yong)(yong)(yong)漏電(dian)(dian)(dian)電(dian)(dian)(dian)流(liu)100MA防止線路(lu)絕緣損(sun)壞發生火(huo)災(zai)的。

使用變頻器時，決不能使用漏電保護器。這是變頻器使用的一大原則。

有些客戶(hu)在使用變頻器(qi)時，為(wei)變頻器(qi)選了相(xiang)應的漏電(dian)保(bao)護器(qi)。最后的結果是：變頻器(qi)一起動(dong)，漏電(dian)保(bao)護器(qi)就動(dong)作，系統根本(ben)無法運行(xing)。

漏(lou)電保護器的(de)原理是(shi)，零(ling)序(xu)電流為零(ling)。使用變(bian)頻器時(shi)，零(ling)序(xu)電流不可能為零(ling)。

變頻(pin)器(qi)輸出側(ce)為PWM波(bo)，電(dian)(dian)(dian)機電(dian)(dian)(dian)纜(lan)與大(da)地(di)之間有長電(dian)(dian)(dian)纜(lan)的電(dian)(dian)(dian)容(rong)效(xiao)應，使用帶(dai)屏(ping)蔽層的電(dian)(dian)(dian)纜(lan)時，電(dian)(dian)(dian)容(rong)效(xiao)應更加明顯。在變頻(pin)器(qi)工(gong)作(zuo)時，電(dian)(dian)(dian)容(rong)在充放電(dian)(dian)(dian)，有電(dian)(dian)(dian)流(liu)通過電(dian)(dian)(dian)容(rong)流(liu)入大(da)地(di)，并從進(jin)(jin)線(xian)側(ce)的接地(di)線(xian)再(zai)流(liu)回變頻(pin)器(qi)，形成(cheng)電(dian)(dian)(dian)流(liu)回路。如(ru)果在進(jin)(jin)線(xian)側(ce)使用了漏電(dian)(dian)(dian)保(bao)護器(qi)，那么它會動作(zuo)，切斷系(xi)統(tong)運(yun)行。

所以，不要為你的變頻器配漏電保護器了。如果要保證安全，做好設備接地就行了。

如下圖所(suo)示，漏(lou)電(dian)(dian)(dian)(dian)(dian)保(bao)護開(kai)關(guan)檢(jian)測的是輸(shu)入(ru)共模電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)，也(ye)就是所(suo)說的對地(di)(di)漏(lou)電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)，檢(jian)測漏(lou)電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)的電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)互感器是同時穿過(guo)(guo)了R/S/T三根(gen)火線(xian)(xian)和(he)零(ling)線(xian)(xian)，在(zai)沒有(you)漏(lou)電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)的情況(kuang)下，不(bu)論接三相(xiang)負載還是接單相(xiang)負載，R/S/T和(he)N線(xian)(xian)這4根(gen)線(xian)(xian)中流(liu)(liu)(liu)(liu)過(guo)(guo)的電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)之和(he)總是為零(ling)。當(dang)(dang)負載側有(you)對地(di)(di)短路現象(xiang)或(huo)者對地(di)(di)有(you)較大(da)(da)的電(dian)(dian)(dian)(dian)(dian)容時，輸(shu)出側的電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)就會通(tong)過(guo)(guo)大(da)(da)地(di)(di)返回(hui)電(dian)(dian)(dian)(dian)(dian)網，此時流(liu)(liu)(liu)(liu)過(guo)(guo)電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)互感器的電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)之和(he)不(bu)為零(ling)，這個(ge)電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)就稱(cheng)之為漏(lou)電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)。當(dang)(dang)檢(jian)測到的電(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)大(da)(da)到一定程度就會觸發保(bao)護開(kai)關(guan)脫扣。

1、變頻器應用中為什么會產生較大的漏電流

普通電(dian)(dian)(dian)(dian)機的(de)(de)繞(rao)組(zu)和(he)機殼之(zhi)間(jian)(jian)存在(zai)著較大的(de)(de)分(fen)布電(dian)(dian)(dian)(dian)容(rong)，在(zai)電(dian)(dian)(dian)(dian)網供電(dian)(dian)(dian)(dian)的(de)(de)情況(kuang)下，電(dian)(dian)(dian)(dian)源線上只有50Hz的(de)(de)工頻(pin)(pin)電(dian)(dian)(dian)(dian)壓(ya)，由(you)于(yu)頻(pin)(pin)率很低(di)，通過分(fen)布電(dian)(dian)(dian)(dian)容(rong)的(de)(de)漏電(dian)(dian)(dian)(dian)流很小。但在(zai)用變(bian)(bian)頻(pin)(pin)器(qi)驅動(dong)電(dian)(dian)(dian)(dian)機時，由(you)于(yu)變(bian)(bian)頻(pin)(pin)器(qi)輸出(chu)(chu)的(de)(de)是幾kHz的(de)(de)PWM(高頻(pin)(pin)脈(mo)寬調制）的(de)(de)電(dian)(dian)(dian)(dian)壓(ya)波形，輸出(chu)(chu)電(dian)(dian)(dian)(dian)壓(ya)是在(zai)0V到(dao)530V之(zhi)間(jian)(jian)快速跳變(bian)(bian)的(de)(de)脈(mo)動(dong)電(dian)(dian)(dian)(dian)壓(ya)，該(gai)脈(mo)動(dong)電(dian)(dian)(dian)(dian)壓(ya)產生諧(xie)波，這些諧(xie)波對于(yu)同樣的(de)(de)電(dian)(dian)(dian)(dian)機同樣的(de)(de)分(fen)布電(dian)(dian)(dian)(dian)容(rong)，漏電(dian)(dian)(dian)(dian)流會(hui)增大百(bai)倍以上，因此容(rong)易發生一(yi)運行(xing)變(bian)(bian)頻(pin)(pin)，漏電(dian)(dian)(dian)(dian)開關就跳閘現(xian)象(xiang)。

2、變頻器輸入端安規電容的作用

輸入端安(an)規電(dian)容的(de)作用主(zhu)要是減小(xiao)(xiao)變頻器(qi)(qi)內(nei)部(bu)對(dui)外(wai)部(bu)電(dian)網(wang)的(de)干擾(rao)影響， 由于(yu)有幾(ji)組的(de)電(dian)容保護，變頻器(qi)(qi)可以承受較大(da)的(de)來(lai)自電(dian)網(wang)的(de)電(dian)壓突波，比如雷擊等，而不至(zhi)于(yu)損壞；由于(yu)變頻器(qi)(qi)中安(an)規電(dian)容取值很小(xiao)(xiao)（2200P），對(dui)于(yu)工(gong)頻的(de)阻抗很大(da)（1.4M），對(dui)漏(lou)電(dian)流的(de)貢獻(xian)很小(xiao)(xiao)（每相約0.15mA ,且三(san)相平衡時(shi)基(ji)波漏(lou)電(dian)流之和為(wei)零(ling)）。

但(dan)如(ru)果(guo)電(dian)網(wang)中的電(dian)壓諧波很高時，電(dian)網(wang)灌入變頻(pin)器的漏(lou)(lou)電(dian)流就會明(ming)顯加大，且三相(xiang)不會抵消(xiao)，漏(lou)(lou)電(dian)流的值與(yu)電(dian)壓諧波的頻(pin)率成(cheng)正比(bi)，與(yu)諧波電(dian)壓的幅值成(cheng)正比(bi)。因(yin)此容易發生漏(lou)(lou)電(dian)開關一合閘(zha)就會跳閘(zha)現象。

3、總結

上述漏電(dian)流可能(neng)會(hui)遠遠大(da)于50mA，而實際的具體數據，將(jiang)與(yu)以(yi)下幾個因(yin)素有關：    

3.1、電機(ji)電纜線的長(chang)度；    

3.2、電機(ji)電纜線是否有屏蔽；    

3.3、變(bian)頻(pin)器(qi)的調制頻(pin)率；    

3.4、是(shi)否使(shi)用無線電射(she)頻干擾(rao)（RFI）濾波器；  ;  

3.5、電(dian)機是否接地。

1、載波頻率：

載波頻率越(yue)高，漏電(dian)(dian)流越(yue)大，漏電(dian)(dian)流的有效(xiao)值與(yu)頻率約為開方關系。

2、輸出頻率：

在(zai)較(jiao)高輸(shu)(shu)出頻(pin)率的情況下，漏(lou)電(dian)流與輸(shu)(shu)出頻(pin)率關系不大，但(dan)在(zai)零頻(pin)附近(jin)時，由于變頻(pin)器三(san)相輸(shu)(shu)出的漏(lou)電(dian)流是疊加關系，漏(lou)電(dian)流的有(you)效值會變大。

3、“零地合一”接線方式對漏電流的影響：

所謂零地(di)合一(yi)指(zhi)的(de)(de)(de)是(shi)將(jiang)電(dian)(dian)網的(de)(de)(de)零線當作地(di)線接到變頻器的(de)(de)(de)PE端子(zi)，由于(yu)變頻器及負載對機(ji)(ji)(ji)殼(ke)的(de)(de)(de)漏電(dian)(dian)流是(shi)通過零線返回電(dian)(dian)網的(de)(de)(de)，而漏電(dian)(dian)保護開關檢(jian)測不到這部(bu)分漏電(dian)(dian)流，理論上講如果變頻器和電(dian)(dian)機(ji)(ji)(ji)負載的(de)(de)(de)機(ji)(ji)(ji)殼(ke)均不接大地(di)（主要是(shi)電(dian)(dian)機(ji)(ji)(ji)機(ji)(ji)(ji)殼(ke)），則漏電(dian)(dian)流可以為零，但實際上無法做到，只(zhi)能改善減(jian)小漏電(dian)(dian)流。

4、輸出電抗器的作用：

在變(bian)頻器U/V/W輸出端(duan)加電抗器,提高了負載的高頻阻抗，可以減小(xiao)漏電流。

變頻器一(yi)般(ban)情況不(bu)會(hui)使用漏電(dian)(dian)斷路器，一(yi)般(ban)采(cai)用接地(di)、等電(dian)(dian)位等措施(shi)來解(jie)決漏電(dian)(dian)問(wen)題。

但(dan)是，為了符合EN50178安全(quan)標(biao)準，必須保(bao)證變頻器(qi)可靠接(jie)地，接(jie)地線(xian)的(de)導線(xian)截面積要為普通接(jie)地線(xian)的(de)2倍或至少10mm2以(yi)上，以(yi)免造成(cheng)人(ren)身傷害。

對于必須要加裝漏(lou)(lou)(lou)電(dian)(dian)(dian)(dian)保(bao)護要求的(de)場合(he)，建議采用符合(he)IEC60755，或VDE0664-100標準所規定的(de)B型(xing)漏(lou)(lou)(lou)電(dian)(dian)(dian)(dian)保(bao)護開(kai)關(guan)(guan)。該漏(lou)(lou)(lou)電(dian)(dian)(dian)(dian)保(bao)護開(kai)關(guan)(guan)充分考(kao)慮到(dao)了(le)電(dian)(dian)(dian)(dian)磁(ci)兼容性(xing)變頻器的(de)特點，很好地解決了(le)具有三相整流裝置的(de)電(dian)(dian)(dian)(dian)氣設備的(de)漏(lou)(lou)(lou)電(dian)(dian)(dian)(dian)保(bao)護問題。

建議請(qing)采用完全(quan)電(dian)(dian)磁(ci)式(shi)，額定(ding)漏電(dian)(dian)動作(zuo)(zuo)電(dian)(dian)流值為(wei)200mA以上，動作(zuo)(zuo)延(yan)時(shi)0.4-1秒左右的漏電(dian)(dian)保(bao)護開關作(zuo)(zuo)變頻器的漏電(dian)(dian)保(bao)護。但不保(bao)證該漏電(dian)(dian)保(bao)護開關一(yi)定(ding)不會跳(tiao)閘(zha)，如跳(tiao)閘(zha)則調整變頻器載最低波頻率(lv)和延(yan)長漏電(dian)(dian)動作(zuo)(zuo)時(shi)間。

變頻(pin)器操(cao)作(zuo)輸出側的漏(lou)電流(liu)(liu)(liu)大(da)(da)約為工頻(pin)操(cao)作(zuo)時的3倍(bei)(bei)多，外加電動機等(deng)漏(lou)電流(liu)(liu)(liu)，選擇漏(lou)電保(bao)護器的動作(zuo)電流(liu)(liu)(liu)應該大(da)(da)于工頻(pin)時漏(lou)電流(liu)(liu)(liu)的10倍(bei)(bei)。必須考慮下列各因素才(cai)能(neng)決定系統(tong)漏(lou)電電流(liu)(liu)(liu)之大(da)(da)小，并選定適當的漏(lou)電保(bao)護開關及必要措施來改(gai)善送電后漏(lou)電保(bao)護開關跳脫之現象(xiang)。

1、一般漏電斷路開關之額定電流選擇計算公式如下：

 I△n ≧ 10×〔Ig1+Ign+3×(Ig2+Igm)〕注(zhu)：

Ig1、Ig2：實際運轉時(shi)電纜(lan)線之(zhi)漏(lou)電電流。         

Ign：變(bian)頻器輸入側噪聲濾波器之漏電(dian)(dian)電(dian)(dian)流。         

Igm：實際運轉時電(dian)機之漏電(dian)電(dian)流。

由上述公式之相關變動參數得知，會影響漏電電流大小之因素有：

1.1 電纜線的(de)漏電電流(liu)(有二部分(fen)）

漏電(dian)斷路(lu)開關(guan)濾波(bo)器的電(dian)纜(lan)線長(chang)之漏電(dian)電(dian)流。

變(bian)頻器、電(dian)機的電(dian)纜線長之漏電(dian)電(dian)流。

1.2 濾(lv)波器(qi)的漏電電流(liu)(包含變(bian)頻器(qi)在(zai)內)。

1.3 馬達(da)的漏電電流(liu)

2、各部分漏電電流值(單位：mA)

2.1 電(dian)(dian)(dian)纜線的漏(lou)電(dian)(dian)(dian)電(dian)(dian)(dian)流(liu)=A×(實際電(dian)(dian)(dian)纜線長/1000m);電(dian)(dian)(dian)纜廠商提供各線徑(jing)每1000m之漏(lou)電(dian)(dian)(dian)電(dian)(dian)(dian)流(liu)值(zhi)A。

 2.2 濾波器的漏電(dian)電(dian)流(包含變頻器在內)一由供應廠商(shang)提供。有的濾波器其漏電(dian)電(dian)流最大值為75mA。

2.3 電機的(de)漏電電流一電機供應(ying)廠商提供。

3、設計舉例

使用變頻器(qi)的數控車(che)床系(xi)統(tong)中，前(qian)端使用了漏電(dian)保護(hu)，但是經常跳脫，分析如下：變頻器(qi)功率(lv)5.5KW，漏電(dian)斷路器(qi)漏電(dian)電(dian)流(liu)75mA。以過(guo)去經驗來(lai)評估時，在一切正(zheng)常的情況下其(qi)中因電(dian)纜線長及電(dian)機本體的漏電(dian)電(dian)流(liu)影響不大(da)，主要影響因素有濾波(bo)器(qi)的漏電(dian)電(dian)流(liu)(含變頻器(qi)在內)及負載側是否依第(di)3種(zhong)接地施工(gong)，

故建議如下：

若電源側(ce)一定要裝漏電斷路(lu)開(kai)關(guan)，建議選(xuan)擇(ze)200mA以上(shang)的(de)感度電流且動作時間(jian)為 0.1秒以上(shang)之漏電斷路(lu)關(guan)開(kai)，但不保證該(gai)漏電斷路(lu)關(guan)開(kai)一定不會跳脫，必須(xu)符合(he)在(zai)它對象(電纜線長及電機)是(shi)正(zheng)常的(de)漏電流范圍內及負載側(ce)是(shi)依(yi)第3種接地施(shi)工下才有效。