一、 電容器損(sun)耗與檢測(ce)
電容器的(de)(de)(de)損(sun)耗(hao)(hao)由(you)介(jie)質(zhi)(zhi)損(sun)耗(hao)(hao)和金屬部分損(sun)耗(hao)(hao)組成。介(jie)質(zhi)(zhi)損(sun)耗(hao)(hao)是由(you)介(jie)質(zhi)(zhi)本(ben)身決定,即由(you)介(jie)質(zhi)(zhi)薄膜的(de)(de)(de)性能——漏導引起的(de)(de)(de)。當使用頻(pin)率(lv)很低(di)時,電容器的(de)(de)(de)損(sun)耗(hao)(hao)主要(yao)由(you)介(jie)質(zhi)(zhi)損(sun)耗(hao)(hao)決定。其(qi)值隨頻(pin)率(lv)上升(sheng)而成反比下(xia)降(jiang)。
(漏導(dao):任(ren)何電(dian)(dian)介質都不是理想的(de)絕緣體,在電(dian)(dian)場的(de)作用下,總有一定(ding)的(de)電(dian)(dian)流(liu)流(liu)過,這種電(dian)(dian)流(liu)很(hen)小,稱作漏導(dao)電(dian)(dian)流(liu)或漏導(dao)。)
金屬(shu)部分(fen)損(sun)耗(hao),其公(gong)(gong)式為:tgδ=ωcRs=2πfcRs(R為電(dian)(dian)(dian)容器等效串聯電(dian)(dian)(dian)阻(zu)(zu)),因(yin)而(er)(er)當(dang)使(shi)(shi)(shi)用(yong)(yong)(yong)頻(pin)率很高(gao)(gao)時,金屬(shu)部分(fen)損(sun)耗(hao)為主(zhu)要(yao)損(sun)耗(hao)。Rs由(you)電(dian)(dian)(dian)容器引(yin)(yin)出(chu)線(xian)電(dian)(dian)(dian)阻(zu)(zu)、極板(ban)電(dian)(dian)(dian)阻(zu)(zu)、極板(ban)與(yu)引(yin)(yin)出(chu)線(xian)之(zhi)間連接引(yin)(yin)起的(de)接觸電(dian)(dian)(dian)阻(zu)(zu)總和。如果連接不好,接觸電(dian)(dian)(dian)阻(zu)(zu)較大(da),那么(me)電(dian)(dian)(dian)容器在(zai)(zai)(zai)(zai)高(gao)(gao)頻(pin)情況(kuang)下(xia)的(de)損(sun)耗(hao)就(jiu)(jiu)很大(da)。使(shi)(shi)(shi)得電(dian)(dian)(dian)容器在(zai)(zai)(zai)(zai)高(gao)(gao)頻(pin)情況(kuang)下(xia)使(shi)(shi)(shi)用(yong)(yong)(yong),發熱嚴重,導致損(sun)壞。因(yin)而(er)(er)使(shi)(shi)(shi)用(yong)(yong)(yong)頻(pin)率較高(gao)(gao)時,須用(yong)(yong)(yong)高(gao)(gao)頻(pin)測(ce)(ce)試,剔除端面接觸不良者。盡(jin)量消(xiao)除使(shi)(shi)(shi)用(yong)(yong)(yong)時的(de)潛在(zai)(zai)(zai)(zai)危險。而(er)(er)用(yong)(yong)(yong)低頻(pin)1KHz就(jiu)(jiu)不能很好有(you)效地剔除接觸不良者。況(kuang)且,CBB類1KHz損(sun)耗(hao)指(zhi)標(biao)為≤0.0003,數值偏小,有(you)時測(ce)(ce)試儀(yi)表之(zhi)間的(de)誤(wu)差可(ke)能達到0.0002。因(yin)而(er)(er),建議(yi)對用(yong)(yong)(yong)在(zai)(zai)(zai)(zai)使(shi)(shi)(shi)用(yong)(yong)(yong)頻(pin)率較高(gao)(gao)的(de)燈上(shang)時,至少用(yong)(yong)(yong)10KHz測(ce)(ce)試,指(zhi)標(biao)≤0.0010,更有(you)把握。我公(gong)(gong)司在(zai)(zai)(zai)(zai)給上(shang)海(hai)光達照明公(gong)(gong)司、深圳垅運(yun)(中(zhong)電(dian)(dian)(dian))照明公(gong)(gong)司等生產燈和鎮流器的(de)廠家(jia)供(gong)貨,都用(yong)(yong)(yong)10KHz檢測(ce)(ce),多年來,保(bao)證了它們(men)完好無損(sun)的(de)使(shi)(shi)(shi)用(yong)(yong)(yong)。
二、電容器耐(nai)壓與檢測
薄膜電(dian)(dian)(dian)(dian)容器(qi)介質(zhi)(zhi)(zhi)的(de)(de)厚度(du)是以其(qi)額(e)定電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)大(da)小來(lai)選取的(de)(de),即介質(zhi)(zhi)(zhi)厚度(du)決定著額(e)定電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)的(de)(de)大(da)小,其(qi)工作電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya),在(zai)頻率適宜(yi)的(de)(de)情況下,一般應不(bu)大(da)于(yu)(yu)(yu)額(e)定電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)。而(er)瞬時(shi)承(cheng)受電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya),即耐(nai)(nai)電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya),按國際國內(nei)標準(zhun)大(da)測試(shi)(shi)電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)為(wei)2倍(bei)(bei)電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya),重(zhong)復進行耐(nai)(nai)電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)試(shi)(shi)驗對(dui)電(dian)(dian)(dian)(dian)容器(qi)有(you)損傷,因而(er)過高(gao)的(de)(de)耐(nai)(nai)電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)超過介質(zhi)(zhi)(zhi)薄膜的(de)(de)承(cheng)受有(you)力,會損傷介質(zhi)(zhi)(zhi)對(dui)電(dian)(dian)(dian)(dian)容器(qi)也(ye)是不(bu)利的(de)(de)。經(jing)過我們多年的(de)(de)試(shi)(shi)驗,這些(xie)潛在(zai)的(de)(de)危險,會減少其(qi)使(shi)用壽命。因而(er)建議客戶給(gei)出(chu)的(de)(de)電(dian)(dian)(dian)(dian)容器(qi)耐(nai)(nai)電(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)指標應不(bu)大(da)于(yu)(yu)(yu)2倍(bei)(bei)。而(er)且在(zai)這種條(tiao)件下,電(dian)(dian)(dian)(dian)容器(qi)廠家為(wei)了(le)更好地保證(zheng)客戶使(shi)用,還要(yao)高(gao)于(yu)(yu)(yu)2倍(bei)(bei)進行內(nei)控,但(dan)這些(xie)余(yu)量我們也(ye)是靠增加(jia)介質(zhi)(zhi)(zhi)厚度(du)來(lai)保證(zheng)的(de)(de)。如(ru)果客戶給(gei)大(da)于(yu)(yu)(yu)2倍(bei)(bei)甚(shen)至3倍(bei)(bei)的(de)(de)指標,那我們仍(reng)要(yao)加(jia)嚴(yan),這樣無(wu)限制(zhi)(zhi)的(de)(de)加(jia)下去(qu),對(dui)電(dian)(dian)(dian)(dian)容器(qi)是一種損害,對(dui)照(zhao)明(ming)產(chan)(chan)品(pin)也(ye)是一種損害,即使(shi)當時(shi)生產(chan)(chan)、檢測過程(cheng)中沒有(you)體(ti)現出(chu)來(lai),但(dan)是卻為(wei)日(ri)后用戶的(de)(de)使(shi)用埋下了(le)隱患,這對(dui)電(dian)(dian)(dian)(dian)容器(qi)供(gong)應商(shang),照(zhao)明(ming)產(chan)(chan)品(pin)制(zhi)(zhi)造商(shang)及消(xiao)費(fei)者三方都是不(bu)利的(de)(de)。因為(wei)我們共同的(de)(de)目標就(jiu)是滿足消(xiao)費(fei)者的(de)(de)使(shi)用。
三、金(jin)屬化內(nei)串電(dian)容器與箔式內(nei)串電(dian)容器的(de)區別
1.電(dian)(dian)(dian)容(rong)器的(de)(de)(de)(de)(de)好壞,除用容(rong)量(liang)、損耗(hao)、絕(jue)緣、耐壓四(si)個(ge)基本參(can)數衡量(liang)檢測外。它的(de)(de)(de)(de)(de)耐脈(mo)(mo)沖(chong)電(dian)(dian)(dian)壓沖(chong)擊和承受電(dian)(dian)(dian)流大(da)(da)小等性(xing)(xing)能也是需要考(kao)(kao)慮(lv)的(de)(de)(de)(de)(de)。在(zai)燈的(de)(de)(de)(de)(de)電(dian)(dian)(dian)路中(zhong)使用的(de)(de)(de)(de)(de)電(dian)(dian)(dian)容(rong)器這(zhe)兩點更需要注意。鑒(jian)于(yu)這(zhe)兩點性(xing)(xing)能的(de)(de)(de)(de)(de)考(kao)(kao)慮(lv),腳距(ju)為(wei)10的(de)(de)(de)(de)(de)體積較小的(de)(de)(de)(de)(de)金(jin)(jin)(jin)屬(shu)化(hua)內串(chuan)(chuan)不好腳距(ju)為(wei)15體積較大(da)(da)的(de)(de)(de)(de)(de)箔(bo)式(shi)內串(chuan)(chuan)的(de)(de)(de)(de)(de)結構(gou)(gou)(gou),因為(wei)金(jin)(jin)(jin)屬(shu)化(hua)內串(chuan)(chuan)結構(gou)(gou)(gou)的(de)(de)(de)(de)(de)極(ji)板與引(yin)出的(de)(de)(de)(de)(de)連(lian)(lian)接端(duan)(duan)面是介質薄膜(mo),而(er)該連(lian)(lian)接部位的(de)(de)(de)(de)(de)接觸電(dian)(dian)(dian)阻(zu)較大(da)(da),加(jia)脈(mo)(mo)沖(chong)時,瞬間流過的(de)(de)(de)(de)(de)電(dian)(dian)(dian)流很大(da)(da),引(yin)起發熱,而(er)塑料(liao)薄膜(mo)介質不耐熱,遇熱收縮,造成端(duan)(duan)面接觸惡化(hua),使等效(xiao)串(chuan)(chuan)聯電(dian)(dian)(dian)阻(zu)更大(da)(da),如(ru)此,惡性(xing)(xing)循環,會很快(kuai)使薄膜(mo)電(dian)(dian)(dian)容(rong)失效(xiao),而(er)鋁箔(bo)做端(duan)(duan)面的(de)(de)(de)(de)(de)肉串(chuan)(chuan)結構(gou)(gou)(gou),端(duan)(duan)面極(ji)板與引(yin)出線相連(lian)(lian)接的(de)(de)(de)(de)(de)部分是金(jin)(jin)(jin)屬(shu)鋁,金(jin)(jin)(jin)屬(shu)耐熱,因而(er)加(jia)上脈(mo)(mo)沖(chong),有(you)大(da)(da)電(dian)(dian)(dian)流流過時,產(chan)生的(de)(de)(de)(de)(de)熱量(liang)不會使其收縮,仍能保證端(duan)(duan)面良好的(de)(de)(de)(de)(de)接觸。所(suo)以,從耐脈(mo)(mo)沖(chong)擊角度考(kao)(kao)慮(lv),箔(bo)式(shi)內串(chuan)(chuan)分壓結構(gou)(gou)(gou)優于(yu)金(jin)(jin)(jin)屬(shu)化(hua)內串(chuan)(chuan)結構(gou)(gou)(gou)。
2.電(dian)(dian)流(liu)流(liu)過(guo)的(de)路(lu)徑是(shi)極(ji)(ji)板、接觸(chu)(chu)端面、引出線(xian)這幾個金屬(shu)(shu)(shu)部(bu)分(fen)及其(qi)連接處(chu),在引出線(xian)相(xiang)同,不考慮接觸(chu)(chu)電(dian)(dian)阻(zu)的(de)情況下,金屬(shu)(shu)(shu)化(hua)電(dian)(dian)極(ji)(ji)的(de)電(dian)(dian)阻(zu)要(yao)大(da)于(yu)(yu)箔式(shi)(shi)電(dian)(dian)極(ji)(ji)電(dian)(dian)阻(zu)兩(liang)個數(shu)量(liang)級(ji)。因為金屬(shu)(shu)(shu)化(hua)電(dian)(dian)極(ji)(ji)是(shi)在介質薄(bo)膜表(biao)面蒸鍍(du)上(shang)一層薄(bo)薄(bo)的(de)金屬(shu)(shu)(shu)鋁,其(qi)厚度不過(guo)0.05~0.1um。而(er)鋁箔的(de)厚度為6um,因而(er),金屬(shu)(shu)(shu)化(hua)電(dian)(dian)極(ji)(ji)極(ji)(ji)電(dian)(dian)阻(zu)要(yao)遠(yuan)大(da)于(yu)(yu)箔式(shi)(shi)電(dian)(dian)極(ji)(ji)的(de)電(dian)(dian)阻(zu),使(shi)得金屬(shu)(shu)(shu)部(bu)分(fen)的(de)損耗大(da)于(yu)(yu)箔式(shi)(shi)。尤其(qi)是(shi)頻率較高(gao)時,在流(liu)過(guo)電(dian)(dian)流(liu)相(xiang)同時,金屬(shu)(shu)(shu)化(hua)電(dian)(dian)極(ji)(ji)發熱遠(yuan)大(da)于(yu)(yu)箔式(shi)(shi)電(dian)(dian)極(ji)(ji)。因而(er)使(shi)用(yong)頻率較高(gao)、電(dian)(dian)壓較大(da)時,不宜采用(yong)金屬(shu)(shu)(shu)內串結構的(de)電(dian)(dian)容(rong)。
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