繼電(dian)器(qi)主要用于(yu)控(kong)制(zhi)(zhi)與保護電(dian)路(lu)作(zuo)信號(hao)(hao)轉換用。它具有輸(shu)(shu)入(ru)電(dian)路(lu)（又(you)(you)稱感應(ying)元(yuan)件(jian)）和(he)(he)輸(shu)(shu)出電(dian)路(lu)（又(you)(you)稱執行元(yuan)件(jian)）。當感應(ying)元(yuan)件(jian)中的輸(shu)(shu)入(ru)量(liang)（如電(dian)流、電(dian)壓(ya)(ya)、溫(wen)度(du)(du)、壓(ya)(ya)力等）變(bian)化到(dao)某一(yi)(yi)定值(zhi)時繼電(dian)器(qi)動作(zuo)，執行元(yuan)件(jian)便接通和(he)(he)斷開控(kong)制(zhi)(zhi)回路(lu)。繼電(dian)器(qi)是一(yi)(yi)種傳遞信號(hao)(hao)的電(dian)器(qi)，用來(lai)接通和(he)(he)分斷控(kong)制(zhi)(zhi)電(dian)路(lu)。繼電(dian)器(qi)的輸(shu)(shu)入(ru)信號(hao)(hao)可以(yi)是電(dian)壓(ya)(ya)、電(dian)流等量(liang)，也可以(yi)是溫(wen)度(du)(du)、速度(du)(du)、光(guang)、油(you)壓(ya)(ya)等非(fei)電(dian)氣量(liang)，而輸(shu)(shu)出則都是觸頭動作(zuo)。
繼電器的動作迅(xun)速，反應靈敏，是自動化基(ji)本元件之一(yi)。
繼(ji)電(dian)(dian)(dian)器(qi)(qi)的種類和形(xing)式很多，按其(qi)動作原理可分為電(dian)(dian)(dian)磁繼(ji)電(dian)(dian)(dian)器(qi)(qi)、熱力繼(ji)電(dian)(dian)(dian)器(qi)(qi)、速度(du)繼(ji)電(dian)(dian)(dian)器(qi)(qi)及壓力繼(ji)電(dian)(dian)(dian)器(qi)(qi)等。
控制繼(ji)電(dian)(dian)(dian)(dian)器(qi)(qi)(qi)(qi)(qi)種類繁多，常用(yong)的有電(dian)(dian)(dian)(dian)流繼(ji)電(dian)(dian)(dian)(dian)器(qi)(qi)(qi)(qi)(qi)、電(dian)(dian)(dian)(dian)壓繼(ji)電(dian)(dian)(dian)(dian)器(qi)(qi)(qi)(qi)(qi)、中間繼(ji)電(dian)(dian)(dian)(dian)器(qi)(qi)(qi)(qi)(qi)、時間繼(ji)電(dian)(dian)(dian)(dian)器(qi)(qi)(qi)(qi)(qi)、熱繼(ji)電(dian)(dian)(dian)(dian)器(qi)(qi)(qi)(qi)(qi)以及溫度、壓力、計數、頻率、速(su)度繼(ji)電(dian)(dian)(dian)(dian)器(qi)(qi)(qi)(qi)(qi)等(deng)等(deng)，下面對經(jing)常使用(yong)的幾(ji)種繼(ji)電(dian)(dian)(dian)(dian)器(qi)(qi)(qi)(qi)(qi)做(zuo)一簡單(dan)介紹(shao)。
一、電壓、電流繼電器
根據(ju)輸入（線(xian)圈(quan)）電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)大小(xiao)而動作(zuo)(zuo)的(de)(de)繼(ji)(ji)(ji)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)器(qi)(qi)(qi)(qi)(qi)稱為(wei)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)繼(ji)(ji)(ji)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)器(qi)(qi)(qi)(qi)(qi)。按用途(tu)還可以分為(wei)過電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)繼(ji)(ji)(ji)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)器(qi)(qi)(qi)(qi)(qi)和(he)欠電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)繼(ji)(ji)(ji)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)器(qi)(qi)(qi)(qi)(qi)。過電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)繼(ji)(ji)(ji)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)器(qi)(qi)(qi)(qi)(qi)的(de)(de)任務是當電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路發生短路及過流(liu)(liu)(liu)(liu)時(shi)立即(ji)將(jiang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路切(qie)斷，因(yin)此(ci)(ci)過電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)繼(ji)(ji)(ji)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)器(qi)(qi)(qi)(qi)(qi)線(xian)圈(quan)中通過的(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)小(xiao)于整(zheng)定(ding)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)時(shi)，繼(ji)(ji)(ji)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)器(qi)(qi)(qi)(qi)(qi)不動作(zuo)(zuo)，只(zhi)有超過整(zheng)定(ding)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)時(shi)，繼(ji)(ji)(ji)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)器(qi)(qi)(qi)(qi)(qi)才動作(zuo)(zuo)。過電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)繼(ji)(ji)(ji)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)器(qi)(qi)(qi)(qi)(qi)動作(zuo)(zuo)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)整(zheng)定(ding)范(fan)圍(wei): 交流(liu)(liu)(liu)(liu)過流(liu)(liu)(liu)(liu)繼(ji)(ji)(ji)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)器(qi)(qi)(qi)(qi)(qi)為(wei)（110％～350％）IN，直流(liu)(liu)(liu)(liu)過流(liu)(liu)(liu)(liu)繼(ji)(ji)(ji)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)器(qi)(qi)(qi)(qi)(qi)為(wei)（70％～300％）IN。欠電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)繼(ji)(ji)(ji)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)器(qi)(qi)(qi)(qi)(qi)的(de)(de)任務是當電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)過低時(shi)立即(ji)將(jiang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路切(qie)斷，因(yin)此(ci)(ci)欠電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)繼(ji)(ji)(ji)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)器(qi)(qi)(qi)(qi)(qi)線(xian)圈(quan)中通過的(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)大于或(huo)等于整(zheng)定(ding)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)時(shi)，繼(ji)(ji)(ji)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)器(qi)(qi)(qi)(qi)(qi)吸(xi)合(he)，只(zhi)有電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)低于整(zheng)定(ding)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)時(shi)，繼(ji)(ji)(ji)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)器(qi)(qi)(qi)(qi)(qi)才釋(shi)(shi)放(fang)。欠電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)繼(ji)(ji)(ji)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)器(qi)(qi)(qi)(qi)(qi)動作(zuo)(zuo)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)整(zheng)定(ding)范(fan)圍(wei): 吸(xi)合(he)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)為(wei)（30％～50％）IN，釋(shi)(shi)放(fang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)為(wei)（10％～20％）IN。欠電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)繼(ji)(ji)(ji)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)器(qi)(qi)(qi)(qi)(qi)一般是自動復(fu)位的(de)(de)。
與此類(lei)似，電(dian)(dian)壓(ya)繼(ji)電(dian)(dian)器(qi)是根據輸(shu)入(ru)電(dian)(dian)壓(ya)大小(xiao)而動作的(de)繼(ji)電(dian)(dian)器(qi)。過電(dian)(dian)壓(ya)繼(ji)電(dian)(dian)器(qi)動作電(dian)(dian)壓(ya)整定范圍(wei)為(wei)（105％～120％）UN。欠電(dian)(dian)壓(ya)繼(ji)電(dian)(dian)器(qi)吸合電(dian)(dian)壓(ya)調整范圍(wei)為(wei)（30％～50％）UN，釋放電(dian)(dian)壓(ya)調整范圍(wei)為(wei)（7％～20％）UN。
電(dian)磁式(shi)繼電(dian)器(qi)在(zai)電(dian)路(lu)中圖(tu)形和文(wen)字符號如圖(tu)1所示(shi)。
圖1 電磁式繼(ji)電器的圖形和(he)文字符號
二、時間繼電器
從得到的(de)輸(shu)入信(xin)號（線(xian)圈的(de)通電(dian)(dian)或斷(duan)(duan)電(dian)(dian)）開始，經過一定的(de)延時后才(cai)輸(shu)出(chu)信(xin)號（觸頭的(de)閉合或斷(duan)(duan)開）的(de)繼電(dian)(dian)器(qi)(qi)，稱為(wei)時間(jian)繼電(dian)(dian)器(qi)(qi)。時間(jian)繼電(dian)(dian)器(qi)(qi)的(de)種類很多，常用的(de)有空氣式(shi)、電(dian)(dian)動式(shi)、式(shi)等。
1、空(kong)氣式時間(jian)繼電(dian)器
空(kong)(kong)氣(qi)式(shi)時(shi)間繼電(dian)器(qi)由電(dian)磁機構、工(gong)作(zuo)觸頭(tou)和(he)氣(qi)室三(san)部分組成，它(ta)的(de)(de)延(yan)時(shi)是靠空(kong)(kong)氣(qi)的(de)(de)阻(zu)尼作(zuo)用來(lai)實現的(de)(de)。常見(jian)的(de)(de)型(xing)號有(you)JS7-A系列(lie)(lie)，按其控制原理(li)(li)有(you)通電(dian)延(yan)時(shi)和(he)斷電(dian)延(yan)時(shi)兩(liang)種類型(xing)。圖2所(suo)示(shi)為JS7-A系列(lie)(lie)空(kong)(kong)氣(qi)阻(zu)尼式(shi)時(shi)間繼電(dian)器(qi)的(de)(de)工(gong)作(zuo)原理(li)(li)圖。
當(dang)通電(dian)延時(shi)型時(shi)間(jian)繼電(dian)器(qi)的(de)(de)電(dian)磁鐵(tie)線圈(quan)1通電(dian)后，將銜(xian)(xian)鐵(tie)吸(xi)下，于是頂桿6與(yu)(yu)銜(xian)(xian)鐵(tie)間(jian)出現一(yi)(yi)個空隙(xi)，當(dang)與(yu)(yu)頂桿相(xiang)連(lian)的(de)(de)活(huo)塞(sai)在彈(dan)簧(huang)7的(de)(de)作用下由上(shang)向下移動時(shi)，在橡皮膜(mo)上(shang)面形成空氣(qi)稀薄的(de)(de)空間(jian)（氣(qi)室），空氣(qi)由進氣(qi)孔逐漸進入氣(qi)室，活(huo)塞(sai)因(yin)受(shou)到空氣(qi)的(de)(de)阻(zu)力，不能迅速下降，在降到一(yi)(yi)定(ding)位置(zhi)時(shi)，杠桿15使觸頭14動作（常開(kai)觸點閉(bi)合，常閉(bi)觸點斷開(kai)）。線圈(quan)斷電(dian)時(shi)，彈(dan)簧(huang)使銜(xian)(xian)鐵(tie)和活(huo)塞(sai)等(deng)復(fu)位，空氣(qi)經橡皮膜(mo)與(yu)(yu)頂桿6之間(jian)推開(kai)的(de)(de)氣(qi)隙(xi)迅速排出，觸點瞬(shun)時(shi)復(fu)位。
斷(duan)電(dian)(dian)(dian)延時型時間繼電(dian)(dian)(dian)器與(yu)(yu)通電(dian)(dian)(dian)延時型時間繼電(dian)(dian)(dian)器的原理(li)與(yu)(yu)結構均相同，只是將其電(dian)(dian)(dian)磁(ci)機構翻轉180°安裝，即為斷(duan)電(dian)(dian)(dian)延時型。
空氣阻尼式時(shi)間繼(ji)電器的延(yan)時(shi)時(shi)間有0.4～180 s和0.4～60 s兩種規格。它具有延(yan)時(shi)范圍較寬，結(jie)構簡單(dan)，工作可靠，價格低(di)廉(lian)，壽命(ming)長(chang)等優點，是機床交流控制線路中(zhong)常用的時(shi)間繼(ji)電器。
表1所示為JS7-A系列空(kong)氣阻尼式時間(jian)繼(ji)電(dian)器的技術數據，其中JS7-2A型和JS7-4A型既帶有延(yan)時動作觸頭(tou)，又(you)帶有瞬(shun)時動作觸頭(tou)。
圖2 JS7-A系(xi)列時間繼電器工作原理圖
通(tong)電延(yan)時型；（b）斷電延(yan)時型
表1 JS7-A系(xi)列(lie)空(kong)氣阻尼式時間(jian)繼電器的技術數(shu)據
按照(zhao)通電(dian)延(yan)時(shi)和(he)斷電(dian)延(yan)時(shi)兩種形式，空氣阻尼式時(shi)間(jian)繼電(dian)器的(de)延(yan)時(shi)觸頭有: 延(yan)時(shi)打(da)開(kai)常開(kai)觸頭、延(yan)時(shi)打(da)開(kai)常閉觸頭、延(yan)時(shi)閉合常開(kai)觸頭和(he)延(yan)時(shi)閉合常閉觸頭。時(shi)間(jian)繼電(dian)器的(de)圖形符(fu)號(hao)如(ru)圖3所示，文字符(fu)號(hao)為KT。
圖3 時間繼(ji)電器的圖形符號
（a）線(xian)圈(quan)的一般符號；（b）通(tong)電延時線(xian)圈(quan)；（c）斷電延時線(xian)圈(quan)；
（d）延時閉合常(chang)開(kai)觸(chu)(chu)頭；（e）延時斷(duan)開(kai)常(chang)閉觸(chu)(chu)頭；（f）延時斷(duan)開(kai)常(chang)開(kai)觸(chu)(chu)頭；
（g）延時閉合常閉觸(chu)頭(tou)(tou)；（h）瞬(shun)動(dong)常開觸(chu)頭(tou)(tou)；（i）瞬(shun)動(dong)常閉觸(chu)頭(tou)(tou)
2、電(dian)動(dong)式時(shi)間(jian)繼電(dian)器
電動式時(shi)(shi)間繼(ji)電器由同步(bu)電動機、減速齒輪(lun)機構、電磁離合(he)系統及執行(xing)機構組成。電動式時(shi)(shi)間繼(ji)電器延時(shi)(shi)時(shi)(shi)間長(chang)，可(ke)達數十(shi)小時(shi)(shi)，延時(shi)(shi)精度高，但結構復(fu)雜，體積(ji)較(jiao)大。常用的有(you)JS10、JS11系列(lie)和7PR系列(lie)。
3、電(dian)子式時間繼電(dian)器
早期產(chan)(chan)品多(duo)(duo)是阻容式(shi)，近期開發的產(chan)(chan)品多(duo)(duo)為數字式(shi)，又(you)稱計(ji)數式(shi)。其結構(gou)由脈沖(chong)發生(sheng)器(qi)(qi)、計(ji)數器(qi)(qi)、數字顯示(shi)器(qi)(qi)、放大器(qi)(qi)及執(zhi)行機構(gou)組成。電子式(shi)時(shi)間(jian)(jian)繼電器(qi)(qi)具(ju)有(you)(you)延時(shi)時(shi)間(jian)(jian)長、調節方(fang)便、精(jing)度高的優點。有(you)(you)的還帶有(you)(you)數字顯示(shi)，應用很廣，可取(qu)代阻容式(shi)、空氣式(shi)、電動式(shi)等時(shi)間(jian)(jian)繼電器(qi)(qi)。我國(guo)生(sheng)產(chan)(chan)的產(chan)(chan)品有(you)(you)JSS1系列。
三、中間繼電器
中間繼電器的作(zuo)用(yong)是將一個輸入信(xin)(xin)號(hao)變成多個輸出(chu)信(xin)(xin)號(hao)或將信(xin)(xin)號(hao)放大(da)(da)（即增(zeng)大(da)(da)觸(chu)頭容量）。
常用的(de)(de)中(zhong)間(jian)繼電(dian)(dian)(dian)器有(you)JZ7系列(lie)。下(xia)面以 JZ7-62為(wei)例(li)說明其型號意義。JZ為(wei)中(zhong)間(jian)繼電(dian)(dian)(dian)器的(de)(de)代號，7為(wei)設(she)計(ji)序號，62表示有(you)6對常開觸(chu)頭(tou)、2對常閉觸(chu)頭(tou)。表2所示為(wei)JZ7系列(lie)中(zhong)間(jian)繼電(dian)(dian)(dian)器的(de)(de)主(zhu)要(yao)技術數據。
表2 JZ7系列中間繼電器的主要技(ji)術(shu)數據(ju)
四、熱繼電器
熱繼電(dian)器是專門用(yong)來對連續運行的(de)電(dian)動(dong)機(ji)進(jin)行過載及斷相保護，以防止電(dian)動(dong)機(ji)過熱而燒毀的(de)保護電(dian)器。
熱(re)(re)(re)(re)繼(ji)(ji)電(dian)(dian)(dian)(dian)(dian)(dian)器的(de)(de)(de)主要(yao)參數(shu)有(you)熱(re)(re)(re)(re)繼(ji)(ji)電(dian)(dian)(dian)(dian)(dian)(dian)器額定(ding)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)、相數(shu)，熱(re)(re)(re)(re)元(yuan)件額定(ding)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)，整(zheng)定(ding)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)及調節范(fan)圍等(deng)。熱(re)(re)(re)(re)繼(ji)(ji)電(dian)(dian)(dian)(dian)(dian)(dian)器的(de)(de)(de)額定(ding)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)是(shi)(shi)指(zhi)熱(re)(re)(re)(re)繼(ji)(ji)電(dian)(dian)(dian)(dian)(dian)(dian)器中可以安裝的(de)(de)(de)熱(re)(re)(re)(re)元(yuan)件的(de)(de)(de)最大(da)整(zheng)定(ding)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)值。熱(re)(re)(re)(re)元(yuan)件的(de)(de)(de)額定(ding)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)是(shi)(shi)指(zhi)熱(re)(re)(re)(re)元(yuan)件的(de)(de)(de)最大(da)整(zheng)定(ding)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)值。熱(re)(re)(re)(re)繼(ji)(ji)電(dian)(dian)(dian)(dian)(dian)(dian)器的(de)(de)(de)整(zheng)定(ding)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)是(shi)(shi)指(zhi)熱(re)(re)(re)(re)元(yuan)件能(neng)夠長期(qi)通過而不(bu)致引起熱(re)(re)(re)(re)繼(ji)(ji)電(dian)(dian)(dian)(dian)(dian)(dian)器動作的(de)(de)(de)最大(da)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)值。通常熱(re)(re)(re)(re)繼(ji)(ji)電(dian)(dian)(dian)(dian)(dian)(dian)器的(de)(de)(de)整(zheng)定(ding)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)是(shi)(shi)按電(dian)(dian)(dian)(dian)(dian)(dian)動機(ji)的(de)(de)(de)額定(ding)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)設(she)定(ding)的(de)(de)(de)。對于某一熱(re)(re)(re)(re)元(yuan)件的(de)(de)(de)熱(re)(re)(re)(re)繼(ji)(ji)電(dian)(dian)(dian)(dian)(dian)(dian)器，可手動調節整(zheng)定(ding)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)旋(xuan)鈕，通過偏心輪機(ji)構(gou)調整(zheng)雙金屬片與導板的(de)(de)(de)距離(li)，能(neng)在一定(ding)范(fan)圍內(nei)調節其(qi)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)的(de)(de)(de)整(zheng)定(ding)值，使(shi)熱(re)(re)(re)(re)繼(ji)(ji)電(dian)(dian)(dian)(dian)(dian)(dian)器更好地保護電(dian)(dian)(dian)(dian)(dian)(dian)動機(ji)。JR16、JR20系列是(shi)(shi)目前廣泛(fan)應(ying)用的(de)(de)(de)熱(re)(re)(re)(re)繼(ji)(ji)電(dian)(dian)(dian)(dian)(dian)(dian)器。
在電氣原理圖(tu)中，熱繼電器的(de)熱元件和(he)常閉觸頭的(de)圖(tu)形和(he)文(wen)字符號如圖(tu)4所示。
圖4 熱(re)繼電器的圖形和文字符號
熱元件；（b）常閉觸(chu)頭(tou)
五、速度繼電器
速(su)(su)(su)度(du)(du)繼電(dian)器根據電(dian)磁感應(ying)原理制成，用來(lai)在三相交流異步電(dian)動(dong)(dong)(dong)機反(fan)接制動(dong)(dong)(dong)轉(zhuan)速(su)(su)(su)過零時(shi)(shi)，，動(dong)(dong)(dong)切(qie)除反(fan)相序電(dian)源(yuan)。速(su)(su)(su)度(du)(du)繼電(dian)器的動(dong)(dong)(dong)作(zuo)(zuo)轉(zhuan)速(su)(su)(su)一(yi)般不(bu)低于120 r/min，復位轉(zhuan)速(su)(su)(su)約在100 r/min以下。啟動(dong)(dong)(dong)時(shi)(shi)，，果(guo)轉(zhuan)速(su)(su)(su)達到其動(dong)(dong)(dong)作(zuo)(zuo)轉(zhuan)速(su)(su)(su)，則其常開觸(chu)頭(tou)閉(bi)合，常閉(bi)觸(chu)頭(tou)斷開；停車時(shi)(shi)，，果(guo)轉(zhuan)速(su)(su)(su)低于復位轉(zhuan)速(su)(su)(su)，則其常閉(bi)觸(chu)頭(tou)閉(bi)合，常開觸(chu)頭(tou)斷開。工(gong)作(zuo)(zuo)時(shi)(shi)，允許的轉(zhuan)速(su)(su)(su)高達1000～3600r/min。由速(su)(su)(su)度(du)(du)繼電(dian)器正轉(zhuan)和(he)反(fan)轉(zhuan)切(qie)換觸(chu)點的動(dong)(dong)(dong)作(zuo)(zuo)，來(lai)反(fan)映電(dian)動(dong)(dong)(dong)機轉(zhuan)向和(he)速(su)(su)(su)度(du)(du)的變(bian)化。常用的型號有JY1和(he)JF20系(xi)列。速(su)(su)(su)度(du)(du)繼電(dian)器的圖形及文字符號如(ru)圖5所示。
圖(tu)5 速度繼電器的圖(tu)形和文字符(fu)號
; 轉子(zi)；（b）常(chang)開(kai)觸(chu)頭；（c）常(chang)閉觸(chu)頭