一、 單相(xiang)變壓(ya)器工作原理:
當變(bian)壓(ya)器一(yi)次(ci)側(ce)施(shi)加交(jiao)流(liu)電(dian)(dian)壓(ya)U1,流(liu)過一(yi)次(ci)繞(rao)組的(de)電(dian)(dian)流(liu)為I1,則該電(dian)(dian)流(liu)在鐵芯中會(hui)產生交(jiao)變(bian)磁(ci)通(tong),使一(yi)次(ci)繞(rao)組和二(er)次(ci)繞(rao)組發(fa)生電(dian)(dian)磁(ci)聯(lian)系,根據(ju)電(dian)(dian)磁(ci)感應原理,交(jiao)變(bian)磁(ci)通(tong)穿過這兩個(ge)繞(rao)組就(jiu)會(hui)感應出電(dian)(dian)動勢(shi),其大(da)(da)小與繞(rao)組匝數以及主磁(ci)通(tong)的(de)最大(da)(da)值成(cheng)正比,繞(rao)組匝數多(duo)的(de)一(yi)側(ce)電(dian)(dian)壓(ya)高,繞(rao)組匝數少的(de)一(yi)側(ce)電(dian)(dian)壓(ya)低,當變(bian)壓(ya)器二(er)次(ci)側(ce)開路(lu),即變(bian)壓(ya)器空載時,一(yi)二(er)次(ci)端(duan)電(dian)(dian)壓(ya)與一(yi)二(er)次(ci)繞(rao)組匝數成(cheng)正比,變(bian)壓(ya)器起(qi)到變(bian)換電(dian)(dian)壓(ya)的(de)目的(de)。
當變壓(ya)(ya)器二(er)次(ci)側接(jie)入負(fu)載后,在電(dian)(dian)動(dong)勢E2的(de)作用下,將有(you)二(er)次(ci)電(dian)(dian)流(liu)通過,該電(dian)(dian)流(liu)產(chan)生的(de)電(dian)(dian)動(dong)勢,也將作用在同一鐵芯上,起到反向去(qu)磁(ci)(ci)(ci)作用,但因(yin)主磁(ci)(ci)(ci)通取決(jue)于電(dian)(dian)源(yuan)電(dian)(dian)壓(ya)(ya),而U1基本(ben)保持不變,故(gu)一次(ci)繞組(zu)電(dian)(dian)流(liu)必將自(zi)動(dong)增加一個分量產(chan)生磁(ci)(ci)(ci)動(dong)勢F1,以抵消二(er)次(ci)繞組(zu)電(dian)(dian)流(liu)所產(chan)生的(de)磁(ci)(ci)(ci)動(dong)勢F2,在一二(er)次(ci)繞組(zu)電(dian)(dian)流(liu)L1、L2作用下,作用在鐵芯上的(de)總磁(ci)(ci)(ci)動(dong)勢(不計空載電(dian)(dian)流(liu)I0),F1+F2=0,
由于F1=I1N1,F2=I2N2,故
I1N1+I2N2=0,由式可知(zhi),I1和I2同相,所以
I1/I2=N2/N1=1/K
由式可知,一(yi)二次電流(liu)比與一(yi)二次電壓比互為(wei)倒(dao)數(shu),變(bian)(bian)(bian)壓器一(yi)二次繞組功(gong)(gong)率(lv)基本不變(bian)(bian)(bian),(因變(bian)(bian)(bian)壓器自(zi)身損耗較(jiao)其傳(chuan)輸功(gong)(gong)率(lv)相對較(jiao)小),二次繞組電流(liu)I2的大小取決于負載(zai)的需要,所以一(yi)次繞組電流(liu)I1的大小也取決于負載(zai)的需要,變(bian)(bian)(bian)壓器起到了功(gong)(gong)率(lv)傳(chuan)遞的作用。
所謂(wei)變(bian)(bian)(bian)壓器就是(shi)要改變(bian)(bian)(bian)電(dian)(dian)壓,一般發(fa)電(dian)(dian)機(ji)輸出(chu)為(wei)(wei)三(san)相(xiang)(xiang)正弦交(jiao)流電(dian)(dian),分為(wei)(wei)U相(xiang)(xiang)、V相(xiang)(xiang)、W相(xiang)(xiang)。發(fa)電(dian)(dian)機(ji)分三(san)角形連接(jie)(jie)和(he)(he)星型連接(jie)(jie):三(san)角形連接(jie)(jie)就是(shi)將(jiang)三(san)項首尾連接(jie)(jie)起來輸出(chu)三(san)條線(xian)幾(ji)十(shi)所謂(wei)的(de)三(san)相(xiang)(xiang)間的(de)電(dian)(dian)壓有效值(zhi)為(wei)(wei)380V,星型是(shi)將(jiang)三(san)星的(de)首或尾連接(jie)(jie)起來輸出(chu)四條線(xian)分別為(wei)(wei)三(san)相(xiang)(xiang)和(he)(he)地線(xian),而(er)三(san)相(xiang)(xiang)的(de)任(ren)意一相(xiang)(xiang)和(he)(he)地線(xian)的(de)連接(jie)(jie)稱為(wei)(wei)單(dan)項電(dian)(dian)有效值(zhi)為(wei)(wei)220V用于單(dan)相(xiang)(xiang)電(dian)(dian)的(de)變(bian)(bian)(bian)壓器稱為(wei)(wei)單(dan)向變(bian)(bian)(bian)壓器,而(er)
連(lian)接于單相變壓器次級的負載稱為單相負荷。