交流(liu)電(dian)(dian)(dian)(dian)壓(ya)(ya)、電(dian)(dian)(dian)(dian)流(liu)而傳輸交流(liu)電(dian)(dian)(dian)(dian)能(neng)的(de)(de)一種靜止(zhi)的(de)(de)電(dian)(dian)(dian)(dian)器(qi)(qi)(qi)設備。它是根據電(dian)(dian)(dian)(dian)磁感應(ying)的(de)(de)原理(li)實現電(dian)(dian)(dian)(dian)能(neng)傳遞的(de)(de)。變壓(ya)(ya)器(qi)(qi)(qi)就其用(yong)(yong)(yong)途可分為電(dian)(dian)(dian)(dian)力(li)變壓(ya)(ya)器(qi)(qi)(qi)、試驗變壓(ya)(ya)器(qi)(qi)(qi)、儀(yi)用(yong)(yong)(yong)變壓(ya)(ya)器(qi)(qi)(qi)及特(te)殊用(yong)(yong)(yong)途的(de)(de)變壓(ya)(ya)器(qi)(qi)(qi)：電(dian)(dian)(dian)(dian)力(li)變壓(ya)(ya)器(qi)(qi)(qi)是電(dian)(dian)(dian)(dian)力(li)輸配電(dian)(dian)(dian)(dian)、電(dian)(dian)(dian)(dian)力(li)用(yong)(yong)(yong)戶配電(dian)(dian)(dian)(dian)的(de)(de)必(bi)要設備;試驗變壓(ya)(ya)器(qi)(qi)(qi)對電(dian)(dian)(dian)(dian)器(qi)(qi)(qi)設備進行耐壓(ya)(ya)(升壓(ya)(ya))試驗的(de)(de)設備;儀(yi)用(yong)(yong)(yong)變壓(ya)(ya)器(qi)(qi)(qi)作為配電(dian)(dian)(dian)(dian)系統的(de)(de)電(dian)(dian)(dian)(dian)氣測量、繼(ji)電(dian)(dian)(dian)(dian)保護(hu)之用(yong)(yong)(yong)(PT、CT);特(te)殊用(yong)(yong)(yong)途的(de)(de)變壓(ya)(ya)器(qi)(qi)(qi)有冶煉用(yong)(yong)(yong)電(dian)(dian)(dian)(dian)爐變壓(ya)(ya)器(qi)(qi)(qi)、電(dian)(dian)(dian)(dian)焊變壓(ya)(ya)器(qi)(qi)(qi)、電(dian)(dian)(dian)(dian)解用(yong)(yong)(yong)整(zheng)流(liu)變壓(ya)(ya)器(qi)(qi)(qi)、小型調(diao)壓(ya)(ya)變壓(ya)(ya)器(qi)(qi)(qi)等(deng)。

  電(dian)力變(bian)壓器(qi)(qi)(qi)是(shi)(shi)(shi)一(yi)(yi)種靜止的(de)(de)(de)(de)(de)電(dian)氣設備，是(shi)(shi)(shi)用(yong)(yong)來將某(mou)一(yi)(yi)數(shu)值(zhi)(zhi)的(de)(de)(de)(de)(de)交流(liu)(liu)電(dian)壓(電(dian)流(liu)(liu))變(bian)成(cheng)頻率相同的(de)(de)(de)(de)(de)另一(yi)(yi)種或幾種數(shu)值(zhi)(zhi)不同的(de)(de)(de)(de)(de)電(dian)壓(電(dian)流(liu)(liu))的(de)(de)(de)(de)(de)設備。當一(yi)(yi)次繞組(zu)通以交流(liu)(liu)電(dian)時，就(jiu)產(chan)生(sheng)交變(bian)的(de)(de)(de)(de)(de)磁(ci)通，交變(bian)的(de)(de)(de)(de)(de)磁(ci)通通過鐵(tie)芯導磁(ci)作用(yong)(yong)，就(jiu)在二(er)次繞組(zu)中感應出交流(liu)(liu)電(dian)動(dong)勢(shi)。二(er)次感應電(dian)動(dong)勢(shi)的(de)(de)(de)(de)(de)高低與(yu)一(yi)(yi)二(er)次繞組(zu)匝數(shu)的(de)(de)(de)(de)(de)多少(shao)有關，即電(dian)壓大(da)(da)(da)小與(yu)匝數(shu)成(cheng)正比。主要(yao)作用(yong)(yong)是(shi)(shi)(shi)傳輸(shu)電(dian)能，因此，額(e)定(ding)(ding)容(rong)量是(shi)(shi)(shi)它的(de)(de)(de)(de)(de)主要(yao)參數(shu)。額(e)定(ding)(ding)容(rong)量是(shi)(shi)(shi)一(yi)(yi)個表(biao)現功率的(de)(de)(de)(de)(de)慣用(yong)(yong)值(zhi)(zhi)，它是(shi)(shi)(shi)表(biao)征傳輸(shu)電(dian)能的(de)(de)(de)(de)(de)大(da)(da)(da)小，以kVA或MVA表(biao)示，當對(dui)變(bian)壓器(qi)(qi)(qi)施加(jia)額(e)定(ding)(ding)電(dian)壓時，根據它來確定(ding)(ding)在規定(ding)(ding)條件下不超過溫升限(xian)值(zhi)(zhi)的(de)(de)(de)(de)(de)額(e)定(ding)(ding)電(dian)流(liu)(liu)。較為節能的(de)(de)(de)(de)(de)電(dian)力變(bian)壓器(qi)(qi)(qi)是(shi)(shi)(shi)非(fei)晶(jing)合(he)金(jin)鐵(tie)心(xin)配(pei)電(dian)變(bian)壓器(qi)(qi)(qi)，其最(zui)大(da)(da)(da)優點是(shi)(shi)(shi)，空載(zai)損耗值(zhi)(zhi)特低。最(zui)終能否確保空載(zai)損耗值(zhi)(zhi)，是(shi)(shi)(shi)整(zheng)個設計過程中所要(yao)考慮的(de)(de)(de)(de)(de)核心(xin)問(wen)題。當在產(chan)品結構布置時，除要(yao)考慮非(fei)晶(jing)合(he)金(jin)鐵(tie)心(xin)本身不受外力的(de)(de)(de)(de)(de)作用(yong)(yong)外，同時在計算時還須精確合(he)理選取非(fei)晶(jing)合(he)金(jin)的(de)(de)(de)(de)(de)特性參數(shu)。

電(dian)(dian)(dian)力變壓(ya)(ya)(ya)(ya)(ya)器(qi)是發電(dian)(dian)(dian)廠和變電(dian)(dian)(dian)所(suo)的(de)主要設備之一(yi)。變壓(ya)(ya)(ya)(ya)(ya)器(qi)的(de)作用(yong)是多方(fang)面的(de)不僅能(neng)升(sheng)高電(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)把電(dian)(dian)(dian)能(neng)送到用(yong)電(dian)(dian)(dian)地(di)區，還能(neng)把電(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)降低為各級使用(yong)電(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)，以滿足用(yong)電(dian)(dian)(dian)的(de)需(xu)要。總之，升(sheng)壓(ya)(ya)(ya)(ya)(ya)與(yu)降壓(ya)(ya)(ya)(ya)(ya)都必須由變壓(ya)(ya)(ya)(ya)(ya)器(qi)來(lai)完成(cheng)。在電(dian)(dian)(dian)力系統(tong)傳送電(dian)(dian)(dian)能(neng)的(de)過程中，必然會產生(sheng)電(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)和功(gong)率兩部分損耗，在輸送同一(yi)功(gong)率時電(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)損耗與(yu)電(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)成(cheng)反比(bi)，功(gong)率損耗與(yu)電(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)的(de)平方(fang)成(cheng)反比(bi)。利用(yong)變壓(ya)(ya)(ya)(ya)(ya)器(qi)提高電(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)，減少了(le)送電(dian)(dian)(dian)損失。

  變(bian)(bian)(bian)(bian)壓(ya)(ya)(ya)器(qi)(qi)是(shi)由(you)繞在同一鐵(tie)芯上(shang)的(de)(de)(de)兩個或(huo)兩個以(yi)上(shang)的(de)(de)(de)線圈繞組(zu)(zu)(zu)組(zu)(zu)(zu)成，繞組(zu)(zu)(zu)之間(jian)是(shi)通過(guo)(guo)交(jiao)變(bian)(bian)(bian)(bian)磁場而聯系(xi)著并按電(dian)磁感應原理工作。變(bian)(bian)(bian)(bian)壓(ya)(ya)(ya)器(qi)(qi)安(an)裝(zhuang)位置(zhi)應考慮便(bian)于運(yun)(yun)行、檢修和運(yun)(yun)輸，同時應選(xuan)(xuan)擇安(an)全可靠的(de)(de)(de)地方(fang)。在使(shi)用變(bian)(bian)(bian)(bian)壓(ya)(ya)(ya)器(qi)(qi)時必須合(he)理地選(xuan)(xuan)用變(bian)(bian)(bian)(bian)壓(ya)(ya)(ya)器(qi)(qi)的(de)(de)(de)額定(ding)容(rong)量。變(bian)(bian)(bian)(bian)壓(ya)(ya)(ya)器(qi)(qi)空載運(yun)(yun)行時，需(xu)用較大的(de)(de)(de)無功功率。這(zhe)些無功功率要由(you)供電(dian)系(xi)統供給。變(bian)(bian)(bian)(bian)壓(ya)(ya)(ya)器(qi)(qi)的(de)(de)(de)容(rong)量若選(xuan)(xuan)擇過(guo)(guo)大，不但增(zeng)加(jia)了初(chu)投資，而且使(shi)變(bian)(bian)(bian)(bian)壓(ya)(ya)(ya)器(qi)(qi)長期處于空載或(huo)輕載運(yun)(yun)行，使(shi)空載損耗(hao)的(de)(de)(de)比(bi)重增(zeng)大，功率因(yin)數降低，網絡(luo)損耗(hao)增(zeng)加(jia)，這(zhe)樣(yang)運(yun)(yun)行既(ji)不經濟又不合(he)理。變(bian)(bian)(bian)(bian)壓(ya)(ya)(ya)器(qi)(qi)容(rong)量選(xuan)(xuan)擇過(guo)(guo)小，會使(shi)變(bian)(bian)(bian)(bian)壓(ya)(ya)(ya)器(qi)(qi)長期過(guo)(guo)負荷(he)，易損壞(huai)設備。因(yin)此，變(bian)(bian)(bian)(bian)壓(ya)(ya)(ya)器(qi)(qi)的(de)(de)(de)額定(ding)容(rong)量應根據用電(dian)負荷(he)的(de)(de)(de)需(xu)要進(jin)行選(xuan)(xuan)擇，不宜過(guo)(guo)大或(huo)過(guo)(guo)小。