變壓器是用來變換交流電壓、電流而傳輸交流電能的一種靜止的電器設備。它是根據電磁感應的原理實現電能傳遞的。

        變(bian)(bian)(bian)壓(ya)(ya)器(qi)(qi)(qi)是用(yong)(yong)來變(bian)(bian)(bian)換(huan)交(jiao)流電(dian)壓(ya)(ya)、電(dian)流而傳輸交(jiao)流電(dian)能的(de)一種靜止的(de)電(dian)器(qi)(qi)(qi)設備(bei)。它(ta)是根據電(dian)磁感(gan)應的(de)原理實現電(dian)能傳遞的(de)。變(bian)(bian)(bian)壓(ya)(ya)器(qi)(qi)(qi)就其用(yong)(yong)途可分為電(dian)力(li)(li)變(bian)(bian)(bian)壓(ya)(ya)器(qi)(qi)(qi)、試(shi)驗(yan)變(bian)(bian)(bian)壓(ya)(ya)器(qi)(qi)(qi)、儀(yi)(yi)用(yong)(yong)變(bian)(bian)(bian)壓(ya)(ya)器(qi)(qi)(qi)及特殊(shu)用(yong)(yong)途的(de)變(bian)(bian)(bian)壓(ya)(ya)器(qi)(qi)(qi)：電(dian)力(li)(li)變(bian)(bian)(bian)壓(ya)(ya)器(qi)(qi)(qi)是電(dian)力(li)(li)輸配電(dian)、電(dian)力(li)(li)用(yong)(yong)戶(hu)配電(dian)的(de)必要(yao)設備(bei)；試(shi)驗(yan)變(bian)(bian)(bian)壓(ya)(ya)器(qi)(qi)(qi)對電(dian)器(qi)(qi)(qi)設備(bei)進行(xing)耐(nai)壓(ya)(ya)（升壓(ya)(ya)）試(shi)驗(yan)的(de)設備(bei)；儀(yi)(yi)用(yong)(yong)變(bian)(bian)(bian)壓(ya)(ya)器(qi)(qi)(qi)作為配電(dian)系統的(de)電(dian)氣測量、繼電(dian)保護之(zhi)用(yong)(yong)（PT、CT）；特殊(shu)用(yong)(yong)途的(de)變(bian)(bian)(bian)壓(ya)(ya)器(qi)(qi)(qi)有冶煉(lian)用(yong)(yong)電(dian)爐變(bian)(bian)(bian)壓(ya)(ya)器(qi)(qi)(qi)、電(dian)焊變(bian)(bian)(bian)壓(ya)(ya)器(qi)(qi)(qi)、電(dian)解用(yong)(yong)整流變(bian)(bian)(bian)壓(ya)(ya)器(qi)(qi)(qi)、小型(xing)調壓(ya)(ya)變(bian)(bian)(bian)壓(ya)(ya)器(qi)(qi)(qi)等。 

        電(dian)(dian)(dian)(dian)(dian)力變壓(ya)器是(shi)一(yi)種靜止(zhi)的(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)氣設(she)備，是(shi)用(yong)來(lai)將某一(yi)數(shu)值的(de)(de)(de)(de)交(jiao)流電(dian)(dian)(dian)(dian)(dian)壓(ya)（電(dian)(dian)(dian)(dian)(dian)流）變成頻率(lv)相同(tong)的(de)(de)(de)(de)另一(yi)種或(huo)(huo)幾種數(shu)值不(bu)同(tong)的(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)壓(ya)（電(dian)(dian)(dian)(dian)(dian)流）的(de)(de)(de)(de)設(she)備。當一(yi)次(ci)繞組(zu)(zu)通(tong)(tong)(tong)以交(jiao)流電(dian)(dian)(dian)(dian)(dian)時，就(jiu)(jiu)產生交(jiao)變的(de)(de)(de)(de)磁(ci)通(tong)(tong)(tong)，交(jiao)變的(de)(de)(de)(de)磁(ci)通(tong)(tong)(tong)通(tong)(tong)(tong)過鐵(tie)芯導磁(ci)作(zuo)用(yong)，就(jiu)(jiu)在二次(ci)繞組(zu)(zu)中(zhong)感應出交(jiao)流電(dian)(dian)(dian)(dian)(dian)動勢。二次(ci)感應電(dian)(dian)(dian)(dian)(dian)動勢的(de)(de)(de)(de)高低與一(yi)二次(ci)繞組(zu)(zu)匝數(shu)的(de)(de)(de)(de)多少有關，即電(dian)(dian)(dian)(dian)(dian)壓(ya)大(da)(da)(da)小與匝數(shu)成正比。主要(yao)(yao)(yao)作(zuo)用(yong)是(shi)傳輸電(dian)(dian)(dian)(dian)(dian)能，因此，額(e)定(ding)(ding)(ding)容(rong)量是(shi)它(ta)的(de)(de)(de)(de)主要(yao)(yao)(yao)參數(shu)。額(e)定(ding)(ding)(ding)容(rong)量是(shi)一(yi)個表(biao)現功率(lv)的(de)(de)(de)(de)慣用(yong)值，它(ta)是(shi)表(biao)征(zheng)傳輸電(dian)(dian)(dian)(dian)(dian)能的(de)(de)(de)(de)大(da)(da)(da)小，以kVA或(huo)(huo)MVA表(biao)示，當對變壓(ya)器施(shi)加額(e)定(ding)(ding)(ding)電(dian)(dian)(dian)(dian)(dian)壓(ya)時，根據(ju)它(ta)來(lai)確(que)定(ding)(ding)(ding)在規定(ding)(ding)(ding)條件下不(bu)超過溫升限值的(de)(de)(de)(de)額(e)定(ding)(ding)(ding)電(dian)(dian)(dian)(dian)(dian)流。較為節能的(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)力變壓(ya)器是(shi)非晶(jing)合金(jin)鐵(tie)心(xin)配電(dian)(dian)(dian)(dian)(dian)變壓(ya)器，其大(da)(da)(da)優點是(shi)，空(kong)載損(sun)耗值特(te)(te)低。最終能否確(que)保(bao)空(kong)載損(sun)耗值，是(shi)整個設(she)計過程中(zhong)所要(yao)(yao)(yao)考(kao)慮的(de)(de)(de)(de)核心(xin)問題。當在產品結構(gou)布置時，除要(yao)(yao)(yao)考(kao)慮非晶(jing)合金(jin)鐵(tie)心(xin)本身不(bu)受外(wai)力的(de)(de)(de)(de)作(zuo)用(yong)外(wai)，同(tong)時在計算時還(huan)須合理選取非晶(jing)合金(jin)的(de)(de)(de)(de)特(te)(te)性參數(shu)。