橋(qiao)梁式(shi)(shi)起重(zhong)(zhong)機(ji)的電(dian)(dian)氣部分(fen)主要包括各機(ji)構(gou)的電(dian)(dian)動機(ji)、制(zhi)動電(dian)(dian)磁鐵、操作(zuo)電(dian)(dian)器、保護(hu)電(dian)(dian)器等，它是指揮(hui)橋(qiao)式(shi)(shi)起重(zhong)(zhong)機(ji)各機(ji)構(gou)工(gong)作(zuo)的控(kong)制(zhi)系統。

    橋梁式起重機所(suo)用電動機的特點：

    1、反復(fu)短時運行常用三相(xiang)異步電動機，基準接電續率(lv)為25%。

    2、頻繁(fan)的啟動(dong)、制(zhi)動(dong)和反轉(zhuan)。為了減少(shao)啟動(dong)與停車的慣性(xing)，轉(zhuan)子一(yi)般比較細長（轉(zhuan)動(dong)慣性(xing)小），以(yi)得(de)到較短的啟動(dong)時間和較小的啟動(dong)損耗。

    3、經常的(de)過載，電動(dong)機(ji)的(de)最(zui)初啟動(dong)轉矩倍數大。

    4、承受經(jing)常的(de)機(ji)構振動與(yu)沖(chong)擊，具有較強(qiang)的(de)機(ji)械強(qiang)度(du)。

    5、工(gong)作環(huan)境多灰塵，故其防護罩為(wei)封閉(bi)型。因(yin)此，起(qi)重機(ji)上所用的(de)電動(dong)(dong)機(ji)，要有較(jiao)高的(de)機(ji)械(xie)強(qiang)度和過載能力，要能承受(shou)經常的(de)機(ji)械(xie)沖擊各振動(dong)(dong)，轉動(dong)(dong)慣性(xing)要小，適于(yu)快速(su)啟(qi)動(dong)(dong)、運轉等。

    橋式起重機(ji)(ji)(ji)上使用(yong)(yong)的電(dian)(dian)(dian)動(dong)機(ji)(ji)(ji)有交(jiao)流(liu)(liu)和(he)直(zhi)流(liu)(liu)兩(liang)(liang)大類。交(jiao)流(liu)(liu)異(yi)步電(dian)(dian)(dian)動(dong)機(ji)(ji)(ji)以可(ke)分(fen)為籠型(xing)和(he)繞(rao)線(xian)(xian)型(xing)兩(liang)(liang)種(zhong)直(zhi)流(liu)(liu)電(dian)(dian)(dian)動(dong)機(ji)(ji)(ji)按勵(li)(li)磁(ci)方式分(fen)為串勵(li)(li)、復(fu)勵(li)(li)、并勵(li)(li)和(he)他(ta)勵(li)(li)四(si)種(zhong)。籠型(xing)電(dian)(dian)(dian)動(dong)機(ji)(ji)(ji)只(zhi)限于中小(xiao)容量(liang)（22kW以下(xia)）、啟(qi)(qi)動(dong)次數不(bu)多(duo)，沒有調整要(yao)(yao)求、對啟(qi)(qi)動(dong)平滑(hua)性(xing)要(yao)(yao)求不(bu)高、要(yao)(yao)求操(cao)作簡單的場合。而繞(rao)線(xian)(xian)型(xing)電(dian)(dian)(dian)動(dong)機(ji)(ji)(ji)在(zai)轉子繞(rao)組接入適當(dang)的附加電(dian)(dian)(dian)阻后(hou)，可(ke)改善電(dian)(dian)(dian)動(dong)機(ji)(ji)(ji)的啟(qi)(qi)動(dong)性(xing)能（啟(qi)(qi)動(dong)轉距增(zeng)大，啟(qi)(qi)動(dong)電(dian)(dian)(dian)流(liu)(liu)減小(xiao)），或者可(ke)以調節電(dian)(dian)(dian)動(dong)機(ji)(ji)(ji)的轉速，它在(zai)起重機(ji)(ji)(ji)上得(de)到廣泛的應用(yong)(yong)。起重機(ji)(ji)(ji)上所用(yong)(yong)的異(yi)步電(dian)(dian)(dian)動(dong)機(ji)(ji)(ji)屬于起重及冶金(jin)用(yong)(yong)電(dian)(dian)(dian)動(dong)機(ji)(ji)(ji)，當(dang)前(qian)常用(yong)(yong)的主要(yao)(yao)有YZR和(he)YZ兩(liang)(liang)個系(xi)列，其(qi)中YZR系(xi)列為繞(rao)線(xian)(xian)型(xing)轉子電(dian)(dian)(dian)動(dong)機(ji)(ji)(ji)，YZ系(xi)列為籠型(xing)轉子電(dian)(dian)(dian)動(dong)機(ji)(ji)(ji)。