安規電容是指用于這樣的場合，即電容器失效后，不會導致電擊，不危及人身安全。安規電容通常只用于抗干擾電路中的濾波作用。

安(an)規(gui)電容(rong)的放電和(he)普(pu)通電容(rong)不(bu)一樣，普(pu)通電容(rong)在(zai)(zai)外部電源(yuan)斷開后電荷會(hui)(hui)保留(liu)很長時間，如果用手(shou)觸(chu)摸(mo)就會(hui)(hui)被電到，而安(an)規(gui)電容(rong)則沒這個問題(ti)。出于安(an)全考慮和(he)EMC考慮，一般(ban)在(zai)(zai)電源(yuan)入口(kou)建議(yi)加上安(an)規(gui)電容(rong)。

在(zai)交(jiao)流電(dian)(dian)源輸(shu)入端(duan),一般需要(yao)增加3個(ge)安規電(dian)(dian)容來(lai)抑制EMI傳導干擾。它們(men)用在(zai)電(dian)(dian)源濾(lv)波器里，起到電(dian)(dian)源濾(lv)波作(zuo)用，分別對共(gong)模，差模工擾起濾(lv)波作(zuo)用。

Y電(dian)(dian)容(rong)在火線(xian)(xian)和(he)地(di)線(xian)(xian)之間以及(ji)在零線(xian)(xian)和(he)地(di)線(xian)(xian)之間并(bing)接(jie)的(de)電(dian)(dian)容(rong),一般統稱(cheng)為(wei)Y電(dian)(dian)容(rong)。這(zhe)兩個Y電(dian)(dian)容(rong)連接(jie)的(de)位置比較(jiao)關鍵,必須需要(yao)(yao)符合(he)相關安(an)(an)全(quan)標準,以防引起(qi)電(dian)(dian)子設(she)備漏電(dian)(dian)或機(ji)(ji)殼帶(dai)電(dian)(dian),容(rong)易危及(ji)人身安(an)(an)全(quan)及(ji)生命。它們都(dou)屬于(yu)安(an)(an)規電(dian)(dian)容(rong),從而(er)要(yao)(yao)求(qiu)(qiu)電(dian)(dian)容(rong)值不(bu)(bu)能偏(pian)大,而(er)耐(nai)壓(ya)必須較(jiao)高(gao)。一般情況(kuang)下,工(gong)作在亞熱帶(dai)的(de)機(ji)(ji)器(qi),要(yao)(yao)求(qiu)(qiu)對地(di)漏電(dian)(dian)電(dian)(dian)流不(bu)(bu)能超過(guo)0.7mA;工(gong)作在溫帶(dai)機(ji)(ji)器(qi),要(yao)(yao)求(qiu)(qiu)對地(di)漏電(dian)(dian)電(dian)(dian)流不(bu)(bu)能超過(guo)0.35mA。因此,Y電(dian)(dian)容(rong)的(de)總容(rong)量一般都(dou)不(bu)(bu)能超過(guo)4700PF(472)。

Y電(dian)(dian)(dian)(dian)容的(de)電(dian)(dian)(dian)(dian)容量必(bi)須受(shou)到限制(zhi)，從而達(da)到控制(zhi)在額定頻率及額定電(dian)(dian)(dian)(dian)壓(ya)作(zuo)用下，流過它的(de)漏(lou)電(dian)(dian)(dian)(dian)流的(de)大小和(he)對系統EMC性(xing)能(neng)(neng)影響的(de)目的(de)。GJB151規定Y電(dian)(dian)(dian)(dian)容的(de)容量應(ying)不大于(yu)0.1uF。Y電(dian)(dian)(dian)(dian)容除(chu)符合相應(ying)的(de)電(dian)(dian)(dian)(dian)網電(dian)(dian)(dian)(dian)壓(ya)耐壓(ya)外，還要求這種(zhong)電(dian)(dian)(dian)(dian)容器在電(dian)(dian)(dian)(dian)氣(qi)和(he)機械性(xing)能(neng)(neng)方面有足夠(gou)的(de)安全余量，避免在極端(duan)惡(e)劣環境條件(jian)下出(chu)現擊穿短路現象，Y電(dian)(dian)(dian)(dian)容的(de)耐壓(ya)性(xing)能(neng)(neng)對保(bao)護(hu)人身安全具有重要意義。

特(te)別指出：作(zuo)為(wei)安規電(dian)(dian)容(rong)(rong)的(de)(de)Y電(dian)(dian)容(rong)(rong),要求必(bi)(bi)須(xu)取得(de)安全(quan)檢測(ce)機構的(de)(de)認(ren)證(zheng)。Y電(dian)(dian)容(rong)(rong)外觀多為(wei)橙色(se)或藍(lan)色(se),一般都(dou)標(biao)有安全(quan)認(ren)證(zheng)標(biao)志(如UL、CSA等標(biao)識)和耐壓AC250V或AC275V字樣。然而,其真正的(de)(de)直流耐壓高達(da)5000V以(yi)上。必(bi)(bi)須(xu)強調,Y電(dian)(dian)容(rong)(rong)不得(de)隨(sui)意使用標(biao)稱耐壓AC250V或者DC400V之類的(de)(de)普通電(dian)(dian)容(rong)(rong)來代用。

X電(dian)(dian)(dian)(dian)(dian)(dian)容(rong)(rong)在火線和零線抑制之間(jian)(jian)并聯(lian)的(de)電(dian)(dian)(dian)(dian)(dian)(dian)容(rong)(rong),一(yi)般稱之為X電(dian)(dian)(dian)(dian)(dian)(dian)容(rong)(rong)。由于這個電(dian)(dian)(dian)(dian)(dian)(dian)容(rong)(rong)連接的(de)位置也比較關鍵,同樣需要(yao)符合(he)相關安(an)全(quan)(quan)標(biao)準。X電(dian)(dian)(dian)(dian)(dian)(dian)容(rong)(rong)同樣也屬于安(an)規(gui)電(dian)(dian)(dian)(dian)(dian)(dian)容(rong)(rong)之一(yi)。根據實際需要(yao),X電(dian)(dian)(dian)(dian)(dian)(dian)容(rong)(rong)的(de)容(rong)(rong)值允許(xu)比Y電(dian)(dian)(dian)(dian)(dian)(dian)容(rong)(rong)的(de)容(rong)(rong)值大,但此時必(bi)須在X電(dian)(dian)(dian)(dian)(dian)(dian)容(rong)(rong)的(de)兩端(duan)并聯(lian)一(yi)個安(an)規(gui)電(dian)(dian)(dian)(dian)(dian)(dian)阻,用于防止電(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)線拔插時,由于該電(dian)(dian)(dian)(dian)(dian)(dian)容(rong)(rong)的(de)充(chong)放電(dian)(dian)(dian)(dian)(dian)(dian)過程而致電(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)線插頭長時間(jian)(jian)帶電(dian)(dian)(dian)(dian)(dian)(dian)。安(an)全(quan)(quan)標(biao)準規(gui)定,當(dang)正(zheng)在工(gong)作之中的(de)機器電(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)線被拔掉(diao)時,在兩秒鐘(zhong)內,電(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)線插頭兩端(duan)帶電(dian)(dian)(dian)(dian)(dian)(dian)的(de)電(dian)(dian)(dian)(dian)(dian)(dian)壓(或對地(di)電(dian)(dian)(dian)(dian)(dian)(dian)位)必(bi)須小于原來額定工(gong)作電(dian)(dian)(dian)(dian)(dian)(dian)壓的(de)30%。

作為安規電(dian)(dian)容(rong)(rong)之(zhi)一(yi)的(de)(de)X電(dian)(dian)容(rong)(rong),也要求(qiu)必須取得安全檢測機構的(de)(de)認證。X電(dian)(dian)容(rong)(rong)一(yi)般都標(biao)(biao)有安全認證標(biao)(biao)志和耐(nai)壓AC250V或AC275V字樣,但其真(zhen)正的(de)(de)直流耐(nai)壓高達2000V以上,使用的(de)(de)時候不要隨意使用標(biao)(biao)稱耐(nai)壓AC250V或者(zhe)DC400V之(zhi)類的(de)(de)的(de)(de)普(pu)通(tong)電(dian)(dian)容(rong)(rong)來(lai)代用。

通常,X電(dian)容(rong)多選用(yong)紋波(bo)電(dian)流比(bi)較(jiao)大的聚脂薄膜類電(dian)容(rong)。這(zhe)種類型(xing)的電(dian)容(rong),體積(ji)較(jiao)大,但(dan)其允許瞬間充放電(dian)的電(dian)流也(ye)很大,而其內阻相(xiang)應(ying)較(jiao)小(xiao)。普通電(dian)容(rong)紋波(bo)電(dian)流的指標都很低,動(dong)態內阻較(jiao)高。用(yong)普通電(dian)容(rong)代替X電(dian)容(rong),除了電(dian)容(rong)耐壓無(wu)法滿足標準之外(wai),紋波(bo)電(dian)流指標也(ye)難以符(fu)合(he)要求。