電動機在運行中避免燒毀,除了運行前采取必要的各種技術保護措施外,最有效、最實際的防止方法是進行正確的技術維護并安裝電動機保護裝置。主要有以下6點。
1.經常保持電動機的(de)清潔
電(dian)(dian)動(dong)(dong)機(ji)在運行(xing)中(zhong),進風口(kou)周圍至少3米內不(bu)允許(xu)有塵(chen)土、水漬和其他雜物,以防止吸人電(dian)(dian)機(ji)內部,形成短(duan)路(lu)介(jie)質,或損壞導(dao)線絕(jue)緣層,造成匣(xia)間短(duan)路(lu),電(dian)(dian)流增(zeng)大,溫度升高(gao)而燒毀電(dian)(dian)動(dong)(dong)機(ji)。所以,要保證電(dian)(dian)動(dong)(dong)機(ji)有足夠的絕(jue)緣電(dian)(dian)阻,以及良(liang)好的通風冷卻環(huan)境,才能(neng)使電(dian)(dian)動(dong)(dong)機(ji)在長(chang)時(shi)間運行(xing)中(zhong)保持安(an)全穩定的工作狀態。
2.保持電動(dong)機經常在(zai)額定電流下工作
電(dian)動機(ji)(ji)過(guo)載運行,主(zhu)要(yao)原(yuan)因(yin)是由于拖動的(de)(de)負荷過(guo)大,電(dian)壓過(guo)低,或(huo)被帶動的(de)(de)機(ji)(ji)械卡滯(zhi)等造成的(de)(de)。若(ruo)(ruo)過(guo)載時間過(guo)長,電(dian)動機(ji)(ji)將從(cong)電(dian)網中吸收大量的(de)(de)有功功率(lv),電(dian)流便急劇增大,溫度也隨之上(shang)升(sheng),在高溫下電(dian)動機(ji)(ji)的(de)(de)絕緣便老化失效而燒毀。因(yin)此,電(dian)動機(ji)(ji)在運行中,要(yao)注意經常檢查(cha)傳動裝置(zhi)運轉是否靈活、可(ke)靠(kao);連軸器的(de)(de)同心度是否標準;齒(chi)輪傳動的(de)(de)靈活性等,若(ruo)(ruo)發現(xian)(xian)有滯(zhi)卡現(xian)(xian)象,應立即停(ting)機(ji)(ji)查(cha)明(ming)原(yuan)因(yin)排除故障后再運行。
3.經常檢查電(dian)(dian)(dian)動機三相(xiang)電(dian)(dian)(dian)流(liu)(liu)是否平衡三相(xiang)異步電(dian)(dian)(dian)動機,其(qi)三相(xiang)電(dian)(dian)(dian)流(liu)(liu)任何(he)一(yi)相(xiang)電(dian)(dian)(dian)流(liu)(liu)與(yu)其(qi)他兩(liang)相(xiang)電(dian)(dian)(dian)流(liu)(liu)平均值(zhi)之差(cha)不允(yun)許超過10%,這(zhe)樣才(cai)能保證電(dian)(dian)(dian)動機安(an)全運(yun)行。如(ru)果超過則表明電(dian)(dian)(dian)動機有故(gu)障,必須查明原因及時排除。
4.檢(jian)(jian)查電(dian)(dian)動(dong)機的(de)(de)溫度要經常(chang)檢(jian)(jian)查電(dian)(dian)動(dong)機的(de)(de)軸(zhou)(zhou)承、定子、外殼等(deng)部(bu)位的(de)(de)溫度有(you)(you)無(wu)(wu)異(yi)常(chang)變化,尤其對無(wu)(wu)電(dian)(dian)壓、電(dian)(dian)流(liu)和(he)頻率(lv)監(jian)視(shi)(shi)及沒有(you)(you)過(guo)(guo)載(zai)保護(hu)的(de)(de)電(dian)(dian)動(dong)機,對溫升的(de)(de)監(jian)視(shi)(shi)更(geng)為重要。電(dian)(dian)動(dong)機軸(zhou)(zhou)承是否過(guo)(guo)熱,缺油,若發現軸(zhou)(zhou)承附近的(de)(de)溫升過(guo)(guo)高,就應立(li)即停機檢(jian)(jian)查。軸(zhou)(zhou)承的(de)(de)滾動(dong)體、滾道表(biao)面有(you)(you)無(wu)(wu)裂紋(wen)、劃(hua)傷或損缺,軸(zhou)(zhou)承間(jian)隙(xi)是否過(guo)(guo)大晃動(dong),內(nei)環在軸(zhou)(zhou)上有(you)(you)無(wu)(wu)轉動(dong)等(deng)。出現上述任(ren)何一種現象,都(dou)必須更(geng)新軸(zhou)(zhou)承后方可再行作業。
5.觀察電動(dong)機有無振動(dong)、噪(zao)(zao)聲(sheng)和異(yi)(yi)常(chang)(chang)氣味(wei)(wei)。電動(dong)機若出(chu)(chu)現(xian)(xian)振動(dong),會(hui)引起(qi)與之相連的(de)負(fu)載(zai)部分不同心度增高(gao),形成電動(dong)機負(fu)載(zai)增大,出(chu)(chu)現(xian)(xian)超負(fu)荷運(yun)(yun)行(xing),就會(hui)燒毀電動(dong)機。因(yin)此,電動(dong)機在運(yun)(yun)行(xing)中,尤其是(shi)(shi)大功率電動(dong)機更要經常(chang)(chang)檢查地腳(jiao)螺栓、電動(dong)機端(duan)蓋、軸承壓蓋等是(shi)(shi)否松(song)動(dong),接地裝置(zhi)是(shi)(shi)否可靠(kao),發現(xian)(xian)問題(ti)及時(shi)解(jie)決。噪(zao)(zao)聲(sheng)和異(yi)(yi)味(wei)(wei)是(shi)(shi)電動(dong)機運(yun)(yun)轉異(yi)(yi)常(chang)(chang)、隨即出(chu)(chu)現(xian)(xian)嚴重故障(zhang)的(de)前兆,必須隨時(shi)發現(xian)(xian)開查明原因(yin)而(er)排(pai)除。
6.保(bao)證啟(qi)動(dong)(dong)(dong)設(she)備(bei)(bei)正(zheng)常工(gong)作電(dian)動(dong)(dong)(dong)機(ji)啟(qi)動(dong)(dong)(dong)設(she)備(bei)(bei)技術狀態的(de)(de)好壞(huai),對電(dian)動(dong)(dong)(dong)機(ji)的(de)(de)正(zheng)常啟(qi)動(dong)(dong)(dong)起(qi)著決(jue)定性的(de)(de)作用。實(shi)踐證明,絕大(da)多數(shu)燒(shao)毀(hui)(hui)的(de)(de)電(dian)動(dong)(dong)(dong)機(ji),其原因大(da)都是啟(qi)動(dong)(dong)(dong)設(she)備(bei)(bei)工(gong)作不(bu)正(zheng)常造(zao)成(cheng)的(de)(de)。如啟(qi)動(dong)(dong)(dong)設(she)備(bei)(bei)出(chu)現缺相啟(qi)動(dong)(dong)(dong),接觸(chu)器(qi)觸(chu)頭拉(la)弧(hu)、打火等。而(er)(er)啟(qi)動(dong)(dong)(dong)設(she)備(bei)(bei)的(de)(de)維護主要(yao)是清潔(jie)、緊固。如接觸(chu)器(qi)觸(chu)點不(bu)清潔(jie)會(hui)使接觸(chu)電(dian)阻增大(da),引(yin)起(qi)發(fa)(fa)熱(re)燒(shao)毀(hui)(hui)觸(chu)點,造(zao)成(cheng)缺相而(er)(er)燒(shao)毀(hui)(hui)電(dian)動(dong)(dong)(dong)機(ji);接觸(chu)器(qi)吸合線(xian)(xian)(xian)圈(quan)的(de)(de)鐵芯銹(xiu)蝕(shi)和塵積,會(hui)使線(xian)(xian)(xian)圈(quan)吸合不(bu)嚴,并發(fa)(fa)生強(qiang)烈噪聲,增大(da)線(xian)(xian)(xian)圈(quan)電(dian)流,燒(shao)毀(hui)(hui)線(xian)(xian)(xian)圈(quan)而(er)(er)引(yin)發(fa)(fa)故(gu)障(zhang)。
因此,電氣控制柜應設在干燥、通風和便于操作的位置,并定期除塵。經常檢查電動機保護器、接觸器觸點、線圈鐵芯、各接線螺絲等是否可靠,機械部位動作是否靈活,使其保持良好的技術狀態,從而保證啟動工作順利而不燒毀電動機。