什么是的返回系數？
電(dian)(dian)流(liu)繼(ji)(ji)電(dian)(dian)器(qi)的(de)(de)返(fan)(fan)回(hui)系數就(jiu)是(shi)繼(ji)(ji)電(dian)(dian)器(qi)的(de)(de)返(fan)(fan)回(hui)量數值(zhi)(zhi)與動(dong)作量數值(zhi)(zhi)的(de)(de)比值(zhi)(zhi)。比如過流(liu)繼(ji)(ji)電(dian)(dian)器(qi)的(de)(de)返(fan)(fan)回(hui)系數就(jiu)是(shi)返(fan)(fan)回(hui)系數=返(fan)(fan)回(hui)電(dian)(dian)流(liu)/動(dong)作電(dian)(dian)流(liu)，該值(zhi)(zhi)反應繼(ji)(ji)電(dian)(dian)器(qi)的(de)(de)靈(ling)敏性，該值(zhi)(zhi)愈接(jie)近1，則(ze)繼(ji)(ji)電(dian)(dian)器(qi)就(jiu)愈靈(ling)敏，但是(shi)靈(ling)敏度太高的(de)(de)繼(ji)(ji)電(dian)(dian)器(qi)很多時候是(shi)不(bu)適用的(de)(de)，所(suo)以繼(ji)(ji)電(dian)(dian)保護對繼(ji)(ji)電(dian)(dian)器(qi)的(de)(de)返(fan)(fan)回(hui)系數有專門(men)的(de)(de)要求，既不(bu)能過高也(ye)不(bu)能過低。
電流繼電器的返回系數為什么恒小于1？
電(dian)流(liu)繼電(dian)器是過流(liu)動作，小(xiao)于(yu)整定值后返(fan)回(hui)(hui)(hui);為了(le)避免電(dian)流(liu)在整定值附近(jin)時導致繼電(dian)器頻繁啟(qi)動返(fan)回(hui)(hui)(hui)，一(yi)般要設一(yi)個返(fan)回(hui)(hui)(hui)值，例如0.97，電(dian)流(liu)小(xiao)于(yu)0.97才返(fan)回(hui)(hui)(hui)。因(yin)此返(fan)回(hui)(hui)(hui)值要小(xiao)于(yu)1。
繼電(dian)(dian)(dian)(dian)器是(shi)一(yi)種電(dian)(dian)(dian)(dian)子控(kong)制器件(jian)，它具(ju)有(you)控(kong)制系(xi)統（又稱(cheng)輸入(ru)回路(lu)）和(he)被控(kong)制系(xi)統（又稱(cheng)輸出回路(lu)），通常應用(yong)于自動控(kong)制電(dian)(dian)(dian)(dian)路(lu)中(zhong)(zhong)，它實際上是(shi)用(yong)較(jiao)小的電(dian)(dian)(dian)(dian)流去控(kong)制較(jiao)大電(dian)(dian)(dian)(dian)流的一(yi)種“自動開(kai)關”。故在電(dian)(dian)(dian)(dian)路(lu)中(zhong)(zhong)起著(zhu)自動調節、安(an)全保護(hu)、轉換電(dian)(dian)(dian)(dian)路(lu)等作用(yong)。
如何調整電流繼電器的返回系數？
影(ying)響(xiang)返回系(xi)數(shu)的(de)因素(su)較(jiao)多，如(ru)軸尖的(de)光潔度、軸承清潔情況(kuang)、靜(jing)觸點位置等。但影(ying)響(xiang)較(jiao)顯著(zhu)地是舌(she)片(pian)端(duan)部與磁(ci)極(ji)間(jian)的(de)間(jian)隙和舌(she)片(pian)的(de)位置。 返回系(xi)數(shu)的(de)調整(zheng)方法有：
1、改(gai)(gai)變(bian)(bian)(bian)(bian)舌(she)片(pian)(pian)的(de)(de)起(qi)(qi)始(shi)(shi)角(jiao)和終止(zhi)角(jiao) 調整(zheng)繼電(dian)(dian)器左上方的(de)(de)舌(she)片(pian)(pian)起(qi)(qi)始(shi)(shi)位(wei)置(zhi)(zhi)(zhi)(zhi)限制螺桿(gan)(gan)，以改(gai)(gai)變(bian)(bian)(bian)(bian)舌(she)片(pian)(pian)起(qi)(qi)始(shi)(shi)位(wei)置(zhi)(zhi)(zhi)(zhi)角(jiao)，此(ci)時只能(neng)改(gai)(gai)變(bian)(bian)(bian)(bian)動(dong)作(zuo)電(dian)(dian)流，而(er)對返(fan)回(hui)(hui)電(dian)(dian)流幾乎沒有影(ying)響。故(gu)用改(gai)(gai)變(bian)(bian)(bian)(bian)舌(she)片(pian)(pian)的(de)(de)起(qi)(qi)始(shi)(shi)角(jiao)來調整(zheng)動(dong)作(zuo)電(dian)(dian)流和返(fan)回(hui)(hui)系(xi)(xi)數(shu)。舌(she)片(pian)(pian)起(qi)(qi)始(shi)(shi)位(wei)置(zhi)(zhi)(zhi)(zhi)離開(kai)磁極(ji)(ji)的(de)(de)距離愈(yu)大(da)(da)，返(fan)回(hui)(hui)系(xi)(xi)數(shu)愈(yu)小；反之(zhi)，返(fan)回(hui)(hui)系(xi)(xi)數(shu)愈(yu)大(da)(da)。 調整(zheng)繼電(dian)(dian)器右上方的(de)(de)舌(she)片(pian)(pian)終止(zhi)位(wei)置(zhi)(zhi)(zhi)(zhi)限制螺桿(gan)(gan)，以改(gai)(gai)變(bian)(bian)(bian)(bian)舌(she)片(pian)(pian)終止(zhi)位(wei)置(zhi)(zhi)(zhi)(zhi)角(jiao)，此(ci)時只能(neng)改(gai)(gai)變(bian)(bian)(bian)(bian)返(fan)回(hui)(hui)電(dian)(dian)流而(er)對動(dong)作(zuo)電(dian)(dian)流則(ze)無影(ying)響。故(gu)用改(gai)(gai)變(bian)(bian)(bian)(bian)舌(she)片(pian)(pian)的(de)(de)種植角(jiao)來調整(zheng)返(fan)回(hui)(hui)電(dian)(dian)流和返(fan)回(hui)(hui)系(xi)(xi)數(shu)。舌(she)片(pian)(pian)周昂志位(wei)置(zhi)(zhi)(zhi)(zhi)與磁極(ji)(ji)的(de)(de)間隙越(yue)大(da)(da)，返(fan)回(hui)(hui)系(xi)(xi)數(shu)愈(yu)大(da)(da)；反之(zhi)，返(fan)回(hui)(hui)系(xi)(xi)數(shu)愈(yu)小；
2、不改變舌片(pian)的(de)起始角和終止角，而變更舌片(pian)兩端的(de)彎曲(qu)程度(du)以(yi)改變舌片(pian)與磁極間的(de)距離，也(ye)能達到(dao)調整返(fan)(fan)回系(xi)數(shu)的(de)目的(de)。該距離越大返(fan)(fan)回系(xi)數(shu)越大，反之返(fan)(fan)回系(xi)數(shu)越小；
3、適(shi)當調整觸電壓力也能改變返回(hui)系數，但應注意觸電壓力不宜過小。
