如何一眼看懂漏電保護裝置的結構組成及原理?
漏(lou)(lou)電(dian)保(bao)(bao)護(hu)(hu)(hu)裝置(zhi)是低壓配(pei)電(dian)柜中常(chang)用的一種保(bao)(bao)護(hu)(hu)(hu)元器(qi)件,當發生漏(lou)(lou)電(dian)和觸電(dian)時(shi)(shi),且達到保(bao)(bao)護(hu)(hu)(hu)器(qi)所限定的動作(zuo)電(dian)流(liu)值(zhi)時(shi)(shi),就立即(ji)在限定的時(shi)(shi)間內動作(zuo)自動斷開電(dian)源進(jin)行保(bao)(bao)護(hu)(hu)(hu)。漏(lou)(lou)電(dian)保(bao)(bao)護(hu)(hu)(hu)裝置(zhi)主要按(an)其(qi)保(bao)(bao)護(hu)(hu)(hu)功能和用途分類進(jin)行敘述(shu),一般(ban)可分為漏(lou)(lou)電(dian)保(bao)(bao)護(hu)(hu)(hu)繼電(dian)器(qi)、漏(lou)(lou)電(dian)保(bao)(bao)護(hu)(hu)(hu)開關和漏(lou)(lou)電(dian)保(bao)(bao)護(hu)(hu)(hu)插座三(san)種。下面詳細講解一下漏(lou)(lou)電(dian)保(bao)(bao)護(hu)(hu)(hu)裝置(zhi)。
一、漏電保(bao)護裝(zhuang)置的結(jie)構組成
(1)檢測(ce)元件。由零序互感器組(zu)成,檢測(ce)漏電(dian)電(dian)流(liu),并(bing)發出信(xin)號。
(2)中間環節(jie)。將(jiang)微弱的(de)漏電信號(hao)放大(da),按裝(zhuang)(zhuang)置(zhi)不同(放大(da)部件可(ke)采用機械裝(zhuang)(zhuang)置(zhi)或電子裝(zhuang)(zhuang)置(zhi)),構成電磁式(shi)保(bao)護(hu)器相電子式(shi)保(bao)護(hu)器。
(3)執行(xing)機構。收到(dao)信號后,主開關由(you)閉合(he)位置轉(zhuan)換到(dao)斷開位置,從而切斷電(dian)源,是(shi)被保護(hu)電(dian)路脫離電(dian)網的跳閘(zha)部件。
二、漏電保護裝置的原理
(1)當電氣(qi)設備發生漏(lou)電時,出現(xian)兩(liang)種(zhong)異常現(xian)象:一是(shi),相電流的平衡(heng)遭到(dao)破壞,出現(xian)零序電流;二是(shi),正常 時不帶電的金屬外(wai)殼出現(xian)對地(di)電壓(ya)(正常時,金屬外(wai)殼與大(da)地(di)均為零電位)。
(2)零(ling)序電流(liu)互感器(qi)(qi)的作用漏電保護器(qi)(qi)通過電流(liu)互感器(qi)(qi)檢測取得異常訊號,經(jing)過中間機構轉(zhuan)換(huan)傳遞,使執行機構動(dong)作,通過開關裝置(zhi)斷開電源。電流(liu)互感器(qi)(qi)的結(jie)構 與(yu)變壓(ya)器(qi)(qi)類似,是由兩(liang)個互相絕緣繞在(zai)同一鐵心上(shang)的線(xian)(xian)圈組成。當(dang)一次線(xian)(xian)圈有剩余電流(liu)時,二次線(xian)(xian)圈就會感應出電流(liu)。
(3)漏(lou)(lou)電(dian)保(bao)護(hu)器工(gong)作原理將漏(lou)(lou)電(dian)保(bao)護(hu)器安(an)裝在(zai)線路中,一次(ci)線圈(quan)與電(dian)網的線路相連接(jie)(jie),二次(ci)線圈(quan)與漏(lou)(lou)電(dian)保(bao)護(hu)器中的脫(tuo)扣器連接(jie)(jie)。
三、注意事項
(1)漏(lou)(lou)電(dian)保護器(qi)適用(yong)于(yu)電(dian)源(yuan)(yuan)中性點(dian)直(zhi)接接地(di)(di)或(huo)(huo)經過電(dian)阻、電(dian)抗接地(di)(di)的(de)低(di)壓配電(dian)系統。對于(yu)電(dian)源(yuan)(yuan)中性點(dian)不(bu)(bu)接地(di)(di)的(de)系統,則(ze)不(bu)(bu)宜采用(yong)漏(lou)(lou)電(dian)保護器(qi)因為后者不(bu)(bu)能構(gou)成泄(xie)漏(lou)(lou)電(dian)氣(qi)回路,即(ji)使發(fa)生(sheng)(sheng)了(le)接地(di)(di)故障,產生(sheng)(sheng)了(le)大(da)于(yu)或(huo)(huo)等于(yu)漏(lou)(lou)電(dian)保護器(qi)的(de)額定動作(zuo)(zuo)(zuo)電(dian)流(liu)(liu),該保護器(qi)也不(bu)(bu)能及時(shi)動作(zuo)(zuo)(zuo)切(qie)斷電(dian)源(yuan)(yuan)回路;或(huo)(huo)者依(yi)靠人體接能故障點(dian)去構(gou)成泄(xie)漏(lou)(lou)電(dian)氣(qi)回路,促使漏(lou)(lou)電(dian)保護器(qi)動作(zuo)(zuo)(zuo),切(qie)斷電(dian)源(yuan)(yuan)回路。但是,這對人體仍不(bu)(bu)安全(quan)。顯而易(yi)見(jian),必(bi)須(xu)具備接地(di)(di)裝置的(de)條(tiao)件,電(dian)氣(qi)設備發(fa)生(sheng)(sheng)漏(lou)(lou)電(dian)時(shi),且漏(lou)(lou)電(dian)電(dian)流(liu)(liu)達(da)到動作(zuo)(zuo)(zuo)電(dian)流(liu)(liu)時(shi),就能在0.1秒內立即(ji)跳閘,切(qie)斷了(le)電(dian)源(yuan)(yuan)主回路。
(2)漏電(dian)保護(hu)器保護(hu)線路(lu)的(de)工作中(zhong)性線N要(yao)通過零序(xu)電(dian)流互感器。否則,在接(jie)通后,就會(hui)有一個(ge)不(bu)平衡電(dian)流使漏電(dian)保護(hu)器產(chan)生誤動作。
(3)接(jie)零(ling)(ling)保(bao)(bao)護線(xian)(PE)不準(zhun)通(tong)過零(ling)(ling)序電(dian)(dian)流(liu)(liu)互感(gan)器(qi)(qi)。因(yin)為保(bao)(bao)護線(xian)路(PE)通(tong)過零(ling)(ling)序電(dian)(dian)流(liu)(liu)互感(gan)器(qi)(qi)時,漏(lou)(lou)電(dian)(dian)電(dian)(dian)流(liu)(liu)經PE保(bao)(bao)護線(xian)又回(hui)穿(chuan)過零(ling)(ling)序電(dian)(dian)流(liu)(liu)互感(gan)器(qi)(qi),導致電(dian)(dian)流(liu)(liu)抵消,而互感(gan)器(qi)(qi)上檢測(ce)不出漏(lou)(lou)電(dian)(dian)電(dian)(dian)流(liu)(liu)值。在(zai)出現故障時,造成漏(lou)(lou)電(dian)(dian)保(bao)(bao)護器(qi)(qi)不動(dong)作,起不到保(bao)(bao)護作用。
(4)漏電保護器后面的工作中性線N與保護線(PE)不能合并(bing)為(wei)一體(ti)。如(ru)果二者(zhe)合并(bing)為(wei)一體(ti)時,當出現漏(lou)電(dian)(dian)(dian)故(gu)障或人(ren)體(ti)觸電(dian)(dian)(dian)時,漏(lou)電(dian)(dian)(dian)電(dian)(dian)(dian)流經(jing)由電(dian)(dian)(dian)流互感器(qi)回流,結果又雷同(tong)于情況(kuang)(3),造(zao)成漏(lou)電(dian)(dian)(dian)保護器(qi)拒絕動作(zuo)。
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