電磁繼電器可以用低電壓(ya)、弱電流控(kong)制高電壓(ya)、強電流電路，還可實現遠(yuan)距離(li)操縱和生產自動化(hua)，在現代生活(huo)中(zhong)起著越(yue)來(lai)越(yue)重要的作(zuo)用。

二、電磁繼電器的工作原理

繼電(dian)(dian)(dian)(dian)(dian)器(qi)，一(yi)(yi)般(ban)(ban)指的(de)是(shi)電(dian)(dian)(dian)(dian)(dian)磁(ci)繼電(dian)(dian)(dian)(dian)(dian)器(qi)，也(ye)就是(shi)機械動(dong)作那種。繼電(dian)(dian)(dian)(dian)(dian)器(qi)的(de)作用本質是(shi)用一(yi)(yi)個(ge)回路（一(yi)(yi)般(ban)(ban)是(shi)小電(dian)(dian)(dian)(dian)(dian)流(liu)）去(qu)控制(zhi)另外一(yi)(yi)個(ge)回路（一(yi)(yi)般(ban)(ban)是(shi)大(da)電(dian)(dian)(dian)(dian)(dian)流(liu)）的(de)通(tong)斷(duan)，而(er)且(qie)這個(ge)控制(zhi)過程中，兩個(ge)回路一(yi)(yi)般(ban)(ban)是(shi)隔離(li)的(de)，它(ta)的(de)基本原理，是(shi)利用了(le)電(dian)(dian)(dian)(dian)(dian)磁(ci)效應來控制(zhi)機械觸點達到通(tong)斷(duan)目的(de)，給帶有鐵芯線圈(quan)通(tong)電(dian)(dian)(dian)(dian)(dian)-線圈(quan)電(dian)(dian)(dian)(dian)(dian)流(liu)產生(sheng)磁(ci)場-磁(ci)場吸(xi)附(fu)銜鐵動(dong)作通(tong)斷(duan)觸點，整個(ge)過程是(shi)“小電(dian)(dian)(dian)(dian)(dian)流(liu)-磁(ci)-機械-大(da)電(dian)(dian)(dian)(dian)(dian)流(liu)”這樣一(yi)(yi)個(ge)過程。

只要在線(xian)圈(quan)兩端加上一(yi)(yi)定(ding)的(de)(de)電(dian)壓，線(xian)圈(quan)中就(jiu)會(hui)流過一(yi)(yi)定(ding)的(de)(de)電(dian)流，從(cong)(cong)而產生(sheng)電(dian)磁(ci)效(xiao)應，銜鐵(tie)(tie)就(jiu)會(hui)在電(dian)磁(ci)力吸(xi)引的(de)(de)作(zuo)用下克服返(fan)(fan)回(hui)彈簧的(de)(de)拉力吸(xi)向鐵(tie)(tie)芯，從(cong)(cong)而帶動(dong)銜鐵(tie)(tie)的(de)(de)動(dong)觸點(dian)與靜觸點(dian)（常(chang)開觸點(dian)）吸(xi)合(he)。當線(xian)圈(quan)斷電(dian)后(hou)，電(dian)磁(ci)的(de)(de)吸(xi)力也隨之(zhi)消失(shi)，銜鐵(tie)(tie)就(jiu)會(hui)在彈簧的(de)(de)反作(zuo)用力返(fan)(fan)回(hui)原來(lai)的(de)(de)位(wei)置，使動(dong)觸點(dian)與原來(lai)的(de)(de)靜觸點(dian)（常(chang)閉(bi)觸點(dian)）釋(shi)放。這樣(yang)吸(xi)合(he)、釋(shi)放，從(cong)(cong)而達到了在電(dian)路中的(de)(de)導通、切斷的(de)(de)目的(de)(de)。對于繼電(dian)器(qi)的(de)(de)“常(chang)(chang)開(kai)、常(chang)(chang)閉(bi)”觸(chu)點，可以(yi)這樣(yang)來區(qu)分：繼(ji)電器線(xian)圈未通(tong)(tong)電時處(chu)于斷開(kai)狀態(tai)的靜觸(chu)點，稱為(wei)“常(chang)(chang)開(kai)觸(chu)點”；處(chu)于接通(tong)(tong)狀態(tai)的靜觸(chu)點稱為(wei)“常(chang)(chang)閉(bi)觸(chu)點”。

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三、電磁繼電器的應用

防訊(xun)報警器(qi)：水位上漲超過警戒(jie)線時，浮子(zi)上升，使控制電(dian)路接通(tong)，電(dian)磁鐵(tie)吸下銜鐵(tie)，于是報警器(qi)指示燈(deng)電(dian)路接通(tong)，燈(deng)亮報警。

溫度自動(dong)報(bao)(bao)警器：當溫度升(sheng)高到一(yi)定值時，水(shui)銀溫度計中水(shui)銀面(mian)上升(sheng)到金屬(shu)(shu)絲(si)處，水(shui)銀是導體。因(yin)此(ci)將電(dian)(dian)磁(ci)鐵電(dian)(dian)路(lu)接(jie)通，電(dian)(dian)磁(ci)鐵吸引(yin)彈簧(huang)片(pian)，使電(dian)(dian)鈴(ling)電(dian)(dian)路(lu)閉(bi)合，電(dian)(dian)鈴(ling)響報(bao)(bao)警，當溫度下降后，水(shui)銀面(mian)離開(kai)(kai)金屬(shu)(shu)絲(si)，電(dian)(dian)磁(ci)鐵電(dian)(dian)路(lu)斷開(kai)(kai)，彈簧(huang)片(pian)回原狀(zhuang)，電(dian)(dian)鈴(ling)電(dian)(dian)路(lu)斷開(kai)(kai)，電(dian)(dian)鈴(ling)不(bu)再發聲。