【電(dian)流(liu)互(hu)(hu)感(gan)器(qi)】電(dian)流(liu)互(hu)(hu)感(gan)器(qi)是什么意思(si) 電(dian)流(liu)互(hu)(hu)感(gan)器(qi)的作用
電流互感器是什么意思
電流互感器是依據電磁感應原理將一次側大電流轉換成二次側小電流來測量的儀器。電流互感器是由閉合的(de)鐵(tie)心和繞組組成。它的(de)一(yi)次(ci)側繞組匝(za)數很少,串在需(xu)要測量的(de)電(dian)流的(de)線(xian)路中。
因(yin)此它經常有線路的全部電(dian)(dian)流(liu)(liu)(liu)流(liu)(liu)(liu)過,二(er)次(ci)側(ce)繞(rao)組(zu)匝數比較多,串(chuan)接在(zai)測(ce)量(liang)(liang)儀(yi)表和保護回(hui)路中,電(dian)(dian)流(liu)(liu)(liu)互感器在(zai)工作時(shi),它的二(er)次(ci)側(ce)回(hui)路始終是(shi)閉合的,因(yin)此測(ce)量(liang)(liang)儀(yi)表和保護回(hui)路串(chuan)聯線圈的阻(zu)抗很小,電(dian)(dian)流(liu)(liu)(liu)互感器的工作狀態接近(jin)短路。電(dian)(dian)流(liu)(liu)(liu)互感器是(shi)把一次(ci)側(ce)大電(dian)(dian)流(liu)(liu)(liu)轉換成二(er)次(ci)側(ce)小電(dian)(dian)流(liu)(liu)(liu)來測(ce)量(liang)(liang) ,二次側不(bu)可開路。
電流互感器的作用
電流互感器的主(zhu)要作用是用來將(jiang)交流電(dian)路(lu)中的大電(dian)流轉換(huan)為(wei)一定(ding)比例的小電(dian)流(我國(guo)標準為(wei)5安倍),以供測(ce)(ce)(ce)量(liang)(liang)和繼電(dian)(dian)(dian)(dian)保護只(zhi)之用(yong)。在發電(dian)(dian)(dian)(dian)、變電(dian)(dian)(dian)(dian)、輸電(dian)(dian)(dian)(dian)、配電(dian)(dian)(dian)(dian)過程中由(you)于用(yong)電(dian)(dian)(dian)(dian)設(she)備的(de)(de)不同(tong),電(dian)(dian)(dian)(dian)流(liu)往(wang)往(wang)從幾十安到幾萬安都(dou)有,而且這些(xie)電(dian)(dian)(dian)(dian)路(lu)(lu)還可能伴(ban)隨高(gao)(gao)壓(ya)。那么為(wei)了能夠對這些(xie)線路(lu)(lu)的(de)(de)電(dian)(dian)(dian)(dian)路(lu)(lu)進(jin)行監(jian)控(kong)、測(ce)(ce)(ce)量(liang)(liang),同(tong)時又要解決高(gao)(gao)壓(ya)、高(gao)(gao)電(dian)(dian)(dian)(dian)流(liu)帶(dai)來的(de)(de)危險,這時就需(xu)要用(yong)到電(dian)(dian)(dian)(dian)流(liu)互(hu)感(gan)器(qi)了。電(dian)(dian)(dian)(dian)工用(yong)的(de)(de)鉗(qian)形表 ,這是一種用(yong)來測(ce)(ce)(ce)量(liang)(liang)交流(liu)電(dian)(dian)(dian)(dian)流(liu)的(de)(de)設(she)備,它那個(ge)“鉗(qian)”便是穿(chuan)心式(shi)電(dian)(dian)(dian)(dian)流(liu)互(hu)感(gan)器(qi)。
電流互感器的工作原理
在發電(dian)(dian)(dian)、變(bian)電(dian)(dian)(dian)、輸電(dian)(dian)(dian)、配電(dian)(dian)(dian)和(he)用電(dian)(dian)(dian)的線路中電(dian)(dian)(dian)流大小(xiao)懸(xuan)殊,從幾(ji)安到幾(ji)萬(wan)安都有(you)。為便(bian)于測量(liang)、保護和(he)控(kong)制需要轉換為比較(jiao)統一的電(dian)(dian)(dian)流,另外線路上的電(dian)(dian)(dian)壓一般都比較(jiao)高(gao)如直接測量(liang)是非(fei)常危險的。電(dian)(dian)(dian)流互感器就(jiu)起到電(dian)(dian)(dian)流變(bian)換和(he)電(dian)(dian)(dian)氣隔離作用。
對(dui)于指針式的(de)(de)電(dian)流表,電(dian)流互(hu)感器的(de)(de)二(er)次電(dian)流大(da)多數是安培(pei)級(ji)的(de)(de)(如5A等)。對于數(shu)字(zi)化儀表,采樣的信(xin)號一般為毫安級(0-5V、4-20mA等)。微型電(dian)流互感器(qi)(qi)二次電(dian)流為毫安(an)級,主(zhu)要起大互感器(qi)(qi)與采樣(yang)之間的橋梁作用。
微(wei)型電流互感器也有人稱之為(wei)“儀(yi)用(yong)(yong)(yong)電流互(hu)感(gan)器(qi)(qi)”。(“儀(yi)用(yong)(yong)(yong)電流互(hu)感(gan)器(qi)(qi)”有一層(ceng)含(han)義是在實驗室使用(yong)(yong)(yong)的多電流比精密電流互(hu)感(gan)器(qi)(qi),一般用(yong)(yong)(yong)于擴大儀(yi)表量程。)
電(dian)(dian)流(liu)互(hu)感(gan)器與(yu)變(bian)壓器類(lei)似也(ye)是(shi)根據電(dian)(dian)磁感(gan)應原(yuan)理工作,變(bian)壓器變(bian)換的是(shi)電(dian)(dian)壓而電(dian)(dian)流(liu)互(hu)感(gan)器變(bian)換的是(shi)電(dian)(dian)流(liu)罷了。電(dian)(dian)流(liu)互(hu)感(gan)器接被測電(dian)(dian)流(liu)的繞組(匝數(shu)為(wei)N1),稱為一次(ci)繞(rao)組(或原邊繞(rao)組、初級繞(rao)組);接測量儀表的繞(rao)組(匝數為N2)稱為(wei)二次繞(rao)組(zu)(或(huo)副(fu)邊繞(rao)組(zu)、次級繞(rao)組(zu))。
電流互感器一次繞組電流I1與(yu)二次(ci)繞組I2的(de)電流比(bi),叫實際電流比(bi)K。電流互(hu)感(gan)器(qi)在額定電流下工作時的(de)電流比(bi)叫電流互(hu)感(gan)器(qi)額定電流比(bi),用Kn表示。
Kn=I1n/I2n
電流互感器(Current transformer 簡稱CT)的作用(yong)(yong)是可以把數值較(jiao)(jiao)大(da)的一(yi)次電流通(tong)過一(yi)定的變(bian)比轉(zhuan)換(huan)為(wei)數值較(jiao)(jiao)小(xiao)的二次電流,用(yong)(yong)來進(jin)行保護、測量等用(yong)(yong)途(tu)。如變(bian)比為(wei)400/5的電流互感器(qi),可(ke)以把實際為400A的(de)電流轉變為5A的(de)電流(liu)。