原勵(li)(li)磁(ci)(ci)系統(tong)電(dian)(dian)(dian)氣原理，虛框內為(wei)旋(xuan)轉勵(li)(li)磁(ci)(ci)部(bu)分，安裝在與(yu)電(dian)(dian)(dian)機(ji)(ji)一(yi)起(qi)轉動(dong)的整(zheng)流盤上，其工作原理為(wei)交流勵(li)(li)磁(ci)(ci)機(ji)(ji)電(dian)(dian)(dian)樞輸出經(jing)三相(xiang)全橋(qiao)整(zheng)流后，經(jing)投勵(li)(li)晶(jing)閘管T1，輸出至(zhi)同步電(dian)(dian)(dian)機(ji)(ji)轉子(zi)，達到投勵(li)(li)目(mu)的。晶(jing)閘管T2、T3及觸(chu)發(fa)(fa)(fa)模(mo)塊(kuai)M2構成起(qi)動(dong)電(dian)(dian)(dian)路，電(dian)(dian)(dian)機(ji)(ji)異步起(qi)動(dong)過(guo)程中轉子(zi)感應電(dian)(dian)(dian)流正負半(ban)波分別流經(jing)T2、T3與(yu)轉子(zi)形成回路。二極(ji)管D7、D8與(yu)電(dian)(dian)(dian)阻串(chuan)聯并在電(dian)(dian)(dian)機(ji)(ji)轉子(zi)上作為(wei)停機(ji)(ji)滅磁(ci)(ci)。觸(chu)發(fa)(fa)(fa)模(mo)塊(kuai)M1、觸(chu)發(fa)(fa)(fa)模(mo)塊(kuai)M2分別為(wei)投勵(li)(li)晶(jing)閘管T1、起(qi)動(dong)晶(jing)閘管T2、T3提供觸(chu)發(fa)(fa)(fa)信號。

　　變壓器的有載分接開關是一種可以在勵磁條件下使分接位置發生變化的電器裝置。無勵磁開關有載分接開關工作的基本原理是：首先在變壓器繞組中引出若干個分接頭，使其在不中斷負載電流的情況下，通過從一個分接頭切換到另一個分接頭來改變有效匝數，改變變壓器的電壓比，以此達到調節電壓的目的。在變化分接頭時，一般采用電阻式組合型的有載分接開關，利用電阻來幫助其過度，用電阻來限制其過渡時的環流問題。在實際的應用中，電阻限流有載分接開關一般由切換開關、選擇開關操作開關三部分組成。    

　　旋(xuan)轉勵(li)磁系(xi)統(tong)由(you)(you)主(zhu)電(dian)(dian)(dian)路(lu)和控制電(dian)(dian)(dian)路(lu)組成(cheng)。主(zhu)電(dian)(dian)(dian)路(lu)包括三相半控橋式整流電(dian)(dian)(dian)路(lu)和起動電(dian)(dian)(dian)路(lu)，主(zhu)電(dian)(dian)(dian)路(lu)電(dian)(dian)(dian)氣圖如圖2所(suo)示。起動電(dian)(dian)(dian)路(lu)由(you)(you)起動晶(jing)閘(zha)管(guan)(guan)-V7、二極管(guan)(guan)-V8及起動電(dian)(dian)(dian)阻R1、R2組成(cheng)。該電(dian)(dian)(dian)路(lu)取消了(le)直流回(hui)路(lu)投勵(li)晶(jing)閘(zha)管(guan)(guan)，解(jie)決了(le)由(you)(you)于(yu)(yu)直流側電(dian)(dian)(dian)流大而引起的投勵(li)晶(jing)閘(zha)管(guan)(guan)過(guo)熱的電(dian)(dian)(dian)流瓶頸現(xian)象，同時避免(mian)了(le)由(you)(you)于(yu)(yu)投勵(li)晶(jing)閘(zha)管(guan)(guan)的損(sun)(sun)壞導致(zhi)的電(dian)(dian)(dian)機失(shi)磁現(xian)象，并且任意一個功(gong)率(lv)組件損(sun)(sun)壞都不會導致(zhi)電(dian)(dian)(dian)機立即失(shi)磁。