過和熱繼電器的區別：
過(guo)電(dian)(dian)流(liu)繼(ji)電(dian)(dian)器(qi)(qi)是用(yong)于回路中電(dian)(dian)流(liu)跨(kua)過(guo)設定值(zhi)時動作，熱繼(ji)電(dian)(dian)器(qi)(qi)通(tong)常用(yong)于電(dian)(dian)機(ji)的(de)過(guo)載(zai)維護，避(bi)免(mian)電(dian)(dian)機(ji)過(guo)載(zai)；熱繼(ji)電(dian)(dian)器(qi)(qi)是用(yong)于電(dian)(dian)動機(ji)或其它電(dian)(dian)氣(qi)設備、電(dian)(dian)氣(qi)線路的(de)過(guo)載(zai)維護的(de)維護電(dian)(dian)器(qi)(qi)。
電(dian)(dian)(dian)動(dong)(dong)(dong)機(ji)(ji)(ji)在實習(xi)作業中，如拖(tuo)動(dong)(dong)(dong)出產機(ji)(ji)(ji)械進(jin)(jin)行作業進(jin)(jin)程中，若(ruo)機(ji)(ji)(ji)械呈現不(bu)正常(chang)的(de)狀況或電(dian)(dian)(dian)路(lu)反常(chang)使(shi)(shi)電(dian)(dian)(dian)動(dong)(dong)(dong)時(shi)(shi)機(ji)(ji)(ji)到過(guo)(guo)載(zai)(zai)(zai)，則(ze)電(dian)(dian)(dian)動(dong)(dong)(dong)機(ji)(ji)(ji)轉速降低、繞(rao)(rao)組(zu)(zu)中的(de)電(dian)(dian)(dian)流(liu)將增大(da)，使(shi)(shi)電(dian)(dian)(dian)動(dong)(dong)(dong)機(ji)(ji)(ji)的(de)繞(rao)(rao)組(zu)(zu)溫(wen)度增加。若(ruo)過(guo)(guo)載(zai)(zai)(zai)電(dian)(dian)(dian)流(liu)不(bu)大(da)且(qie)過(guo)(guo)載(zai)(zai)(zai)的(de)時(shi)(shi)刻(ke)較短(duan)，電(dian)(dian)(dian)動(dong)(dong)(dong)機(ji)(ji)(ji)繞(rao)(rao)組(zu)(zu)不(bu)跨過(guo)(guo)容許溫(wen)升(sheng)(sheng)，這種過(guo)(guo)載(zai)(zai)(zai)是(shi)容許的(de)。但若(ruo)過(guo)(guo)載(zai)(zai)(zai)時(shi)(shi)刻(ke)長，過(guo)(guo)載(zai)(zai)(zai)電(dian)(dian)(dian)流(liu)大(da)，電(dian)(dian)(dian)動(dong)(dong)(dong)機(ji)(ji)(ji)繞(rao)(rao)組(zu)(zu)的(de)溫(wen)升(sheng)(sheng)就(jiu)會(hui)跨過(guo)(guo)容許值，使(shi)(shi)電(dian)(dian)(dian)動(dong)(dong)(dong)機(ji)(ji)(ji)繞(rao)(rao)組(zu)(zu)老化，縮短(duan)電(dian)(dian)(dian)動(dong)(dong)(dong)機(ji)(ji)(ji)的(de)運用(yong)壽數，嚴峻時(shi)(shi)乃至(zhi)會(hui)使(shi)(shi)電(dian)(dian)(dian)動(dong)(dong)(dong)機(ji)(ji)(ji)繞(rao)(rao)組(zu)(zu)焚毀。所以(yi)，這種過(guo)(guo)載(zai)(zai)(zai)是(shi)電(dian)(dian)(dian)動(dong)(dong)(dong)機(ji)(ji)(ji)不(bu)能接(jie)受的(de)。熱繼電(dian)(dian)(dian)器(qi)即是(shi)運用(yong)電(dian)(dian)(dian)流(liu)的(de)熱效應原理，在呈現電(dian)(dian)(dian)動(dong)(dong)(dong)機(ji)(ji)(ji)不(bu)能接(jie)受的(de)過(guo)(guo)載(zai)(zai)(zai)時(shi)(shi)堵截電(dian)(dian)(dian)動(dong)(dong)(dong)機(ji)(ji)(ji)電(dian)(dian)(dian)路(lu)，為(wei)電(dian)(dian)(dian)動(dong)(dong)(dong)機(ji)(ji)(ji)供應過(guo)(guo)載(zai)(zai)(zai)維護的(de)維護電(dian)(dian)(dian)器(qi)。
運用熱(re)(re)繼電(dian)(dian)器(qi)(qi)對電(dian)(dian)動(dong)機進行(xing)過(guo)(guo)載維護(hu)時，將(jiang)熱(re)(re)元件與(yu)電(dian)(dian)動(dong)機的定子繞(rao)組串(chuan)聯，將(jiang)熱(re)(re)繼電(dian)(dian)器(qi)(qi)的常(chang)閉觸頭串(chuan)聯在溝通觸摸器(qi)(qi)的電(dian)(dian)磁線(xian)圈的操控電(dian)(dian)路(lu)中，并(bing)調度(du)(du)整定電(dian)(dian)流(liu)調度(du)(du)旋鈕，使(shi)人(ren)字(zi)形(xing)(xing)撥(bo)桿與(yu)推桿相(xiang)距一恰當間隔。當電(dian)(dian)動(dong)機正常(chang)作業時，經過(guo)(guo)熱(re)(re)元件的電(dian)(dian)流(liu)即為電(dian)(dian)動(dong)機的額(e)外電(dian)(dian)流(liu)，熱(re)(re)元件發熱(re)(re)，雙金屬片(pian)受熱(re)(re)后(hou)曲折，使(shi)推桿剛好與(yu)人(ren)字(zi)形(xing)(xing)撥(bo)桿觸摸，而又(you)不(bu)能(neng)推進聽字(zi)形(xing)(xing)撥(bo)桿。常(chang)閉觸頭處于閉合狀況，溝通觸摸器(qi)(qi)堅持(chi)吸合，電(dian)(dian)動(dong)機正常(chang)作業。
若電動機呈現(xian)過(guo)載狀況，繞組中電流(liu)增(zeng)大，經過(guo)熱繼電器(qi)元件中的電流(liu)增(zeng)大使雙金屬片(pian)溫度(du)升得更高，曲折程(cheng)度(du)加大，推進(jin)聽(ting)字形撥(bo)桿，人(ren)字形撥(bo)桿推進(jin)常閉觸頭，使觸頭斷(duan)開而斷(duan)開溝通觸摸器(qi)線圈電路(lu)，使觸摸器(qi)開釋、堵截電動機的電源，電動機泊車(che)而得到(dao)維護(hu)。
可見，熱繼電器(qi)通常是直接斷開(kai)觸(chu)摸器(qi)的操控回路來斷開(kai)主回路的。
過電(dian)流(liu)繼電(dian)器：用于(yu)電(dian)機或(huo)其(qi)它(ta)電(dian)氣設備，在電(dian)流(liu)跨過設定(ding)值時動作（吸合）。堵截主電(dian)路，或(huo)宣告(gao)信號。
