一、電解電容在電路中的作用 1,濾波作用,在電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路中,整流(liu)(liu)(liu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路將交流(liu)(liu)(liu)變成(cheng)脈(mo)(mo)動的(de)(de)直(zhi)流(liu)(liu)(liu),而在整流(liu)(liu)(liu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路之(zhi)后(hou)接(jie)入一(yi)(yi)個較(jiao)大容量的(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)解電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)容,利(li)用其充放電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)特(te)性,使整流(liu)(liu)(liu)后(hou)的(de)(de)脈(mo)(mo)動直(zhi)流(liu)(liu)(liu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)變成(cheng)相對(dui)比較(jiao)穩定(ding)的(de)(de)直(zhi)流(liu)(liu)(liu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)。在實際中,為(wei)了防止(zhi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路各部(bu)分供電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)因負(fu)載變化而產生變化,所(suo)以在電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)的(de)(de)輸出端及負(fu)載的(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)輸入端一(yi)(yi)般接(jie)有(you)數十至數百微法的(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)解電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)容.由(you)于大容量的(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)解電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)容一(yi)(yi)般具有(you)一(yi)(yi)定(ding)的(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)感,對(dui)高頻及脈(mo)(mo)沖(chong)干擾(rao)信號不能有(you)效地濾除,故在其兩端并聯(lian)了一(yi)(yi)只容量為(wei)0.001--0.lpF的(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)容,以濾除高頻及脈(mo)(mo)沖(chong)干擾(rao).
2,耦合作用:在(zai)低(di)頻(pin)信號的傳遞與放大過程中,為防(fang)止前后兩級電(dian)(dian)路的靜(jing)態工作點相互影(ying)響,常采用電(dian)(dian)容(rong)(rong)藕(ou)合.為了防(fang)止信號中韻低(di)頻(pin)分量(liang)損失過大,一般總采用容(rong)(rong)量(liang)較大的電(dian)(dian)解電(dian)(dian)容(rong)(rong)。
二、電解電容的判斷方法 電(dian)解(jie)(jie)電(dian)容(rong)(rong)(rong)常(chang)見的故障有(you),容(rong)(rong)(rong)量(liang)(liang)減少,容(rong)(rong)(rong)量(liang)(liang)消失、擊(ji)穿(chuan)短(duan)路(lu)及漏電(dian),其(qi)(qi)中容(rong)(rong)(rong)量(liang)(liang)變化是因(yin)電(dian)解(jie)(jie)電(dian)容(rong)(rong)(rong)在使(shi)用(yong)或(huo)(huo)放置過程中其(qi)(qi)內部的電(dian)解(jie)(jie)液逐漸干涸引(yin)起,而(er)擊(ji)穿(chuan)與漏電(dian)一般為所加(jia)的電(dian)壓過高(gao)或(huo)(huo)本身質(zhi)量(liang)(liang)不(bu)佳引(yin)起。判斷電(dian)源電(dian)容(rong)(rong)(rong)的好(hao)壞一般采用(yong)萬用(yong)表(biao)(biao)(biao)(biao)的電(dian)阻(zu)檔進行(xing)(xing)測(ce)(ce)量(liang)(liang).具體(ti)方法為:將電(dian)容(rong)(rong)(rong)兩管(guan)腳短(duan)路(lu)進行(xing)(xing)放電(dian),用(yong)萬用(yong)表(biao)(biao)(biao)(biao)的黑表(biao)(biao)(biao)(biao)筆接電(dian)解(jie)(jie)電(dian)容(rong)(rong)(rong)的正(zheng)極。紅表(biao)(biao)(biao)(biao)筆接負極(對指(zhi)針(zhen)式萬用(yong)表(biao)(biao)(biao)(biao),用(yong)數字式萬用(yong)表(biao)(biao)(biao)(biao)測(ce)(ce)量(liang)(liang)時(shi)(shi)表(biao)(biao)(biao)(biao)筆互(hu)調),正(zheng)常(chang)時(shi)(shi)表(biao)(biao)(biao)(biao)針(zhen)應先向(xiang)電(dian)阻(zu)小(xiao)(xiao)(xiao)的方向(xiang)擺(bai)動(dong),然后逐漸返(fan)回直至無窮(qiong)大處(chu)。表(biao)(biao)(biao)(biao)針(zhen)的擺(bai)動(dong)幅度越(yue)大或(huo)(huo)返(fan)回的速度越(yue)慢,說(shuo)明電(dian)容(rong)(rong)(rong)的容(rong)(rong)(rong)量(liang)(liang)越(yue)大,反之則說(shuo)明電(dian)容(rong)(rong)(rong)的容(rong)(rong)(rong)量(liang)(liang)越(yue)小(xiao)(xiao)(xiao).如表(biao)(biao)(biao)(biao)針(zhen)指(zhi)在中間某處(chu)不(bu)再變化,說(shuo)明此(ci)電(dian)容(rong)(rong)(rong)漏電(dian),如電(dian)阻(zu)指(zhi)示值很小(xiao)(xiao)(xiao)或(huo)(huo)為零,則表(biao)(biao)(biao)(biao)明此(ci)電(dian)容(rong)(rong)(rong)已擊(ji)穿(chuan)短(duan)路(lu).因(yin)萬用(yong)表(biao)(biao)(biao)(biao)使(shi)用(yong)的電(dian)池電(dian)壓一般很低,所以在測(ce)(ce)量(liang)(liang)低耐壓的電(dian)容(rong)(rong)(rong)時(shi)(shi)比(bi)較準確,而(er)當(dang)電(dian)容(rong)(rong)(rong)的耐壓較高(gao)時(shi)(shi),打(da)時(shi)(shi)盡管(guan)測(ce)(ce)量(liang)(liang)正(zheng)常(chang),但加(jia)上(shang)高(gao)壓時(shi)(shi)則有(you)可能發生漏電(dian)或(huo)(huo)擊(ji)穿(chuan)現象(xiang).
三、電解電容的使用注意事項 1、電(dian)(dian)(dian)(dian)解電(dian)(dian)(dian)(dian)容(rong)(rong)(rong)由(you)于(yu)有正(zheng)(zheng)負極(ji)(ji)性,因(yin)此在電(dian)(dian)(dian)(dian)路(lu)中(zhong)使(shi)用時(shi)不能顛倒聯接(jie)。在電(dian)(dian)(dian)(dian)源電(dian)(dian)(dian)(dian)路(lu)中(zhong),輸(shu)(shu)出(chu)正(zheng)(zheng)電(dian)(dian)(dian)(dian)壓(ya)時(shi)電(dian)(dian)(dian)(dian)解電(dian)(dian)(dian)(dian)容(rong)(rong)(rong)的(de)正(zheng)(zheng)極(ji)(ji)接(jie)電(dian)(dian)(dian)(dian)源輸(shu)(shu)出(chu)端,負極(ji)(ji)接(jie)地(di),輸(shu)(shu)出(chu)負電(dian)(dian)(dian)(dian)壓(ya)時(shi)則負極(ji)(ji)接(jie)輸(shu)(shu)出(chu)端,正(zheng)(zheng)極(ji)(ji)接(jie)地(di).當電(dian)(dian)(dian)(dian)源電(dian)(dian)(dian)(dian)路(lu)中(zhong)的(de)濾(lv)波電(dian)(dian)(dian)(dian)容(rong)(rong)(rong)極(ji)(ji)性接(jie)反時(shi),因(yin)電(dian)(dian)(dian)(dian)容(rong)(rong)(rong)的(de)濾(lv)波作用大(da)(da)大(da)(da)降低,一方面引(yin)起(qi)電(dian)(dian)(dian)(dian)源輸(shu)(shu)出(chu)電(dian)(dian)(dian)(dian)壓(ya)波動,另一方面又因(yin)反向(xiang)通電(dian)(dian)(dian)(dian)使(shi)此時(shi)相當于(yu)一個電(dian)(dian)(dian)(dian)阻的(de)電(dian)(dian)(dian)(dian)解電(dian)(dian)(dian)(dian)容(rong)(rong)(rong)發熱(re).當反向(xiang)電(dian)(dian)(dian)(dian)壓(ya)超過某值(zhi)時(shi),電(dian)(dian)(dian)(dian)容(rong)(rong)(rong)的(de)反向(xiang)漏電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)阻將變得很小,這樣通電(dian)(dian)(dian)(dian)工作不久,即(ji)可使(shi)電(dian)(dian)(dian)(dian)容(rong)(rong)(rong)因(yin)過熱(re)而炸裂損壞.
2.加(jia)在電(dian)(dian)解電(dian)(dian)容(rong)兩端的(de)電(dian)(dian)壓(ya)不能超過其允許工作電(dian)(dian)壓(ya),在設計(ji)實(shi)際電(dian)(dian)路時(shi)應根據具體情況留有(you)一(yi)定的(de)余量,在設計(ji)穩壓(ya)電(dian)(dian)源(yuan)(yuan)的(de)濾波電(dian)(dian)容(rong)時(shi),如(ru)(ru)果交流(liu)電(dian)(dian)源(yuan)(yuan)電(dian)(dian)壓(ya)為220~時(shi)變(bian)壓(ya)器(qi)次級(ji)的(de)整(zheng)流(liu)電(dian)(dian)壓(ya)可達22V,此時(shi)選(xuan)(xuan)擇(ze)耐壓(ya)為25V的(de)電(dian)(dian)解電(dian)(dian)容(rong)一(yi)般可以滿足要求.但是,假(jia)如(ru)(ru)交流(liu)電(dian)(dian)源(yuan)(yuan)電(dian)(dian)壓(ya)波動很大且有(you)可能上升到250V以上時(shi),好選(xuan)(xuan)擇(ze)耐壓(ya)30V以上的(de)電(dian)(dian)解電(dian)(dian)容(rong)。
3,電解電容在電路(lu)中不應靠近大(da)功率(lv)發熱(re)元件,以防因受熱(re)而(er)使(shi)電解液(ye)加速干涸(he).
4、對于有正(zheng)負(fu)極(ji)(ji)性(xing)的(de)(de)信號的(de)(de)濾(lv)波,可采取兩個(ge)電(dian)解電(dian)容同極(ji)(ji)性(xing)串聯(lian)的(de)(de)方法,當作一個(ge)無極(ji)(ji)性(xing)的(de)(de)電(dian)容
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