一、 電容器損耗與檢測
電容(rong)(rong)器(qi)的(de)損耗(hao)(hao)由(you)介質(zhi)損耗(hao)(hao)和金屬部分損耗(hao)(hao)組(zu)成(cheng)(cheng)。介質(zhi)損耗(hao)(hao)是由(you)介質(zhi)本身決定,即由(you)介質(zhi)薄膜的(de)性能——漏導引起的(de)。當使用頻率(lv)很低時,電容(rong)(rong)器(qi)的(de)損耗(hao)(hao)主要由(you)介質(zhi)損耗(hao)(hao)決定。其(qi)值隨(sui)頻率(lv)上(shang)升而(er)成(cheng)(cheng)反比下降。
(漏導(dao):任何電介質都不(bu)是理想的絕緣體,在電場的作用下,總有(you)一(yi)定的電流(liu)流(liu)過,這種(zhong)電流(liu)很小(xiao),稱作漏導(dao)電流(liu)或漏導(dao)。)
金(jin)屬部分損(sun)(sun)耗(hao),其公(gong)式為:tgδ=ωcRs=2πfcRs(R為電(dian)容器(qi)(qi)等效串(chuan)聯(lian)電(dian)阻),因(yin)而當使(shi)(shi)用(yong)(yong)(yong)頻率很(hen)(hen)高(gao)時,金(jin)屬部分損(sun)(sun)耗(hao)為主要損(sun)(sun)耗(hao)。Rs由(you)電(dian)容器(qi)(qi)引(yin)出線電(dian)阻、極板電(dian)阻、極板與引(yin)出線之(zhi)間連(lian)接(jie)(jie)引(yin)起(qi)的接(jie)(jie)觸電(dian)阻總和。如果連(lian)接(jie)(jie)不(bu)好(hao),接(jie)(jie)觸電(dian)阻較(jiao)大(da),那么電(dian)容器(qi)(qi)在(zai)(zai)高(gao)頻情況(kuang)下的損(sun)(sun)耗(hao)就(jiu)很(hen)(hen)大(da)。使(shi)(shi)得電(dian)容器(qi)(qi)在(zai)(zai)高(gao)頻情況(kuang)下使(shi)(shi)用(yong)(yong)(yong),發熱(re)嚴重,導(dao)致損(sun)(sun)壞。因(yin)而使(shi)(shi)用(yong)(yong)(yong)頻率較(jiao)高(gao)時,須用(yong)(yong)(yong)高(gao)頻測(ce)試,剔(ti)除端面接(jie)(jie)觸不(bu)良(liang)者。盡量消除使(shi)(shi)用(yong)(yong)(yong)時的潛在(zai)(zai)危險。而用(yong)(yong)(yong)低頻1KHz就(jiu)不(bu)能很(hen)(hen)好(hao)有效地剔(ti)除接(jie)(jie)觸不(bu)良(liang)者。況(kuang)且(qie),CBB類1KHz損(sun)(sun)耗(hao)指(zhi)標(biao)為≤0.0003,數值偏小,有時測(ce)試儀表之(zhi)間的誤差可(ke)能達到0.0002。因(yin)而,建議對用(yong)(yong)(yong)在(zai)(zai)使(shi)(shi)用(yong)(yong)(yong)頻率較(jiao)高(gao)的燈上時,至(zhi)少用(yong)(yong)(yong)10KHz測(ce)試,指(zhi)標(biao)≤0.0010,更有把握。我公(gong)司(si)在(zai)(zai)給上海(hai)光達照(zhao)(zhao)明(ming)公(gong)司(si)、深圳垅運(yun)(中電(dian))照(zhao)(zhao)明(ming)公(gong)司(si)等生產燈和鎮流器(qi)(qi)的廠(chang)家供(gong)貨,都用(yong)(yong)(yong)10KHz檢(jian)測(ce),多年來(lai),保證了它們完好(hao)無損(sun)(sun)的使(shi)(shi)用(yong)(yong)(yong)。
二(er)、電容器耐(nai)壓與(yu)檢測
薄(bo)膜電(dian)(dian)(dian)(dian)容(rong)器(qi)(qi)(qi)介(jie)(jie)(jie)質的(de)(de)(de)(de)(de)(de)厚(hou)度(du)是以(yi)其額(e)定(ding)(ding)電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)大小來選(xuan)取的(de)(de)(de)(de)(de)(de),即介(jie)(jie)(jie)質厚(hou)度(du)決(jue)定(ding)(ding)著額(e)定(ding)(ding)電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)的(de)(de)(de)(de)(de)(de)大小,其工作電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya),在頻率適宜的(de)(de)(de)(de)(de)(de)情(qing)況下(xia),一(yi)般應(ying)(ying)不(bu)(bu)大于(yu)(yu)額(e)定(ding)(ding)電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)。而瞬時承受電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya),即耐電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya),按國際國內標(biao)準大測(ce)試電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)為2倍電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya),重復(fu)進行(xing)耐電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)試驗(yan)對(dui)電(dian)(dian)(dian)(dian)容(rong)器(qi)(qi)(qi)有損(sun)傷(shang),因(yin)而過(guo)高(gao)(gao)的(de)(de)(de)(de)(de)(de)耐電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)超過(guo)介(jie)(jie)(jie)質薄(bo)膜的(de)(de)(de)(de)(de)(de)承受有力,會損(sun)傷(shang)介(jie)(jie)(jie)質對(dui)電(dian)(dian)(dian)(dian)容(rong)器(qi)(qi)(qi)也(ye)(ye)是不(bu)(bu)利(li)的(de)(de)(de)(de)(de)(de)。經過(guo)我們(men)多年的(de)(de)(de)(de)(de)(de)試驗(yan),這(zhe)(zhe)些潛在的(de)(de)(de)(de)(de)(de)危險,會減少(shao)其使用(yong)壽命(ming)。因(yin)而建議客戶(hu)給(gei)出(chu)的(de)(de)(de)(de)(de)(de)電(dian)(dian)(dian)(dian)容(rong)器(qi)(qi)(qi)耐電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)指(zhi)標(biao)應(ying)(ying)不(bu)(bu)大于(yu)(yu)2倍。而且在這(zhe)(zhe)種條件下(xia),電(dian)(dian)(dian)(dian)容(rong)器(qi)(qi)(qi)廠家為了更好地保證(zheng)客戶(hu)使用(yong),還(huan)要高(gao)(gao)于(yu)(yu)2倍進行(xing)內控(kong),但這(zhe)(zhe)些余(yu)量我們(men)也(ye)(ye)是靠增加(jia)介(jie)(jie)(jie)質厚(hou)度(du)來保證(zheng)的(de)(de)(de)(de)(de)(de)。如果客戶(hu)給(gei)大于(yu)(yu)2倍甚至3倍的(de)(de)(de)(de)(de)(de)指(zhi)標(biao),那我們(men)仍要加(jia)嚴(yan),這(zhe)(zhe)樣(yang)無限制的(de)(de)(de)(de)(de)(de)加(jia)下(xia)去,對(dui)電(dian)(dian)(dian)(dian)容(rong)器(qi)(qi)(qi)是一(yi)種損(sun)害,對(dui)照明產(chan)(chan)(chan)品也(ye)(ye)是一(yi)種損(sun)害,即使當(dang)時生產(chan)(chan)(chan)、檢(jian)測(ce)過(guo)程中沒有體現出(chu)來,但是卻為日后用(yong)戶(hu)的(de)(de)(de)(de)(de)(de)使用(yong)埋下(xia)了隱患,這(zhe)(zhe)對(dui)電(dian)(dian)(dian)(dian)容(rong)器(qi)(qi)(qi)供應(ying)(ying)商,照明產(chan)(chan)(chan)品制造商及消(xiao)費者(zhe)三方都(dou)是不(bu)(bu)利(li)的(de)(de)(de)(de)(de)(de)。因(yin)為我們(men)共同的(de)(de)(de)(de)(de)(de)目標(biao)就(jiu)是滿(man)足消(xiao)費者(zhe)的(de)(de)(de)(de)(de)(de)使用(yong)。
三、金屬(shu)化內串電容(rong)器與箔(bo)式(shi)內串電容(rong)器的區別
1.電容器的(de)(de)好壞,除用(yong)容量(liang)、損耗、絕緣、耐壓(ya)四個基(ji)本參(can)數衡量(liang)檢測外(wai)。它的(de)(de)耐脈沖(chong)(chong)(chong)電壓(ya)沖(chong)(chong)(chong)擊和(he)承(cheng)受電流大小(xiao)等性(xing)能(neng)也是需要考(kao)慮的(de)(de)。在燈的(de)(de)電路中使用(yong)的(de)(de)電容器這(zhe)兩點(dian)更需要注意。鑒于(yu)這(zhe)兩點(dian)性(xing)能(neng)的(de)(de)考(kao)慮,腳(jiao)距為10的(de)(de)體(ti)(ti)積較(jiao)小(xiao)的(de)(de)金屬(shu)化內串(chuan)(chuan)不好腳(jiao)距為15體(ti)(ti)積較(jiao)大的(de)(de)箔(bo)式內串(chuan)(chuan)的(de)(de)結構(gou)(gou),因(yin)為金屬(shu)化內串(chuan)(chuan)結構(gou)(gou)的(de)(de)極板與引(yin)(yin)(yin)出(chu)的(de)(de)連接(jie)(jie)端(duan)面(mian)(mian)(mian)是介(jie)質薄(bo)膜,而(er)該連接(jie)(jie)部位的(de)(de)接(jie)(jie)觸(chu)電阻較(jiao)大,加(jia)脈沖(chong)(chong)(chong)時,瞬間流過的(de)(de)電流很(hen)大,引(yin)(yin)(yin)起發熱(re)(re),而(er)塑料薄(bo)膜介(jie)質不耐熱(re)(re),遇熱(re)(re)收(shou)縮,造成端(duan)面(mian)(mian)(mian)接(jie)(jie)觸(chu)惡化,使等效串(chuan)(chuan)聯電阻更大,如(ru)此(ci),惡性(xing)循環,會很(hen)快使薄(bo)膜電容失效,而(er)鋁(lv)(lv)箔(bo)做端(duan)面(mian)(mian)(mian)的(de)(de)肉串(chuan)(chuan)結構(gou)(gou),端(duan)面(mian)(mian)(mian)極板與引(yin)(yin)(yin)出(chu)線相連接(jie)(jie)的(de)(de)部分是金屬(shu)鋁(lv)(lv),金屬(shu)耐熱(re)(re),因(yin)而(er)加(jia)上脈沖(chong)(chong)(chong),有大電流流過時,產生的(de)(de)熱(re)(re)量(liang)不會使其收(shou)縮,仍能(neng)保證(zheng)端(duan)面(mian)(mian)(mian)良好的(de)(de)接(jie)(jie)觸(chu)。所以,從耐脈沖(chong)(chong)(chong)擊角度考(kao)慮,箔(bo)式內串(chuan)(chuan)分壓(ya)結構(gou)(gou)優于(yu)金屬(shu)化內串(chuan)(chuan)結構(gou)(gou)。
2.電(dian)(dian)流流過(guo)的(de)(de)路徑是(shi)(shi)(shi)極(ji)(ji)板(ban)、接(jie)觸端面、引出線(xian)(xian)這(zhe)幾(ji)個金(jin)(jin)(jin)屬(shu)(shu)部(bu)分及其連接(jie)處,在(zai)引出線(xian)(xian)相(xiang)同,不考慮接(jie)觸電(dian)(dian)阻(zu)(zu)的(de)(de)情況下,金(jin)(jin)(jin)屬(shu)(shu)化(hua)(hua)(hua)電(dian)(dian)極(ji)(ji)的(de)(de)電(dian)(dian)阻(zu)(zu)要大(da)于(yu)(yu)(yu)箔式(shi)(shi)電(dian)(dian)極(ji)(ji)電(dian)(dian)阻(zu)(zu)兩個數(shu)量級。因為金(jin)(jin)(jin)屬(shu)(shu)化(hua)(hua)(hua)電(dian)(dian)極(ji)(ji)是(shi)(shi)(shi)在(zai)介質薄膜表面蒸鍍上一層(ceng)薄薄的(de)(de)金(jin)(jin)(jin)屬(shu)(shu)鋁(lv),其厚度不過(guo)0.05~0.1um。而(er)鋁(lv)箔的(de)(de)厚度為6um,因而(er),金(jin)(jin)(jin)屬(shu)(shu)化(hua)(hua)(hua)電(dian)(dian)極(ji)(ji)極(ji)(ji)電(dian)(dian)阻(zu)(zu)要遠(yuan)大(da)于(yu)(yu)(yu)箔式(shi)(shi)電(dian)(dian)極(ji)(ji)的(de)(de)電(dian)(dian)阻(zu)(zu),使(shi)得金(jin)(jin)(jin)屬(shu)(shu)部(bu)分的(de)(de)損耗大(da)于(yu)(yu)(yu)箔式(shi)(shi)。尤其是(shi)(shi)(shi)頻率(lv)較高時,在(zai)流過(guo)電(dian)(dian)流相(xiang)同時,金(jin)(jin)(jin)屬(shu)(shu)化(hua)(hua)(hua)電(dian)(dian)極(ji)(ji)發熱遠(yuan)大(da)于(yu)(yu)(yu)箔式(shi)(shi)電(dian)(dian)極(ji)(ji)。因而(er)使(shi)用頻率(lv)較高、電(dian)(dian)壓較大(da)時,不宜采用金(jin)(jin)(jin)屬(shu)(shu)內串(chuan)結構的(de)(de)電(dian)(dian)容。
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