如何選購電動機 電動機的維護保養步驟

一、電動機的選購。電動機的選購應遵循以下步驟：

⑴查(cha)看外觀：電(dian)(dian)動(dong)(dong)(dong)機(ji)表面油(you)漆層應(ying)(ying)光(guang)滑平整，銘牌安裝端(duan)正(zheng)，標(biao)志齊全(quan)；封閉式電(dian)(dian)動(dong)(dong)(dong)機(ji)座(zuo)(zuo)散熱(re)筋應(ying)(ying)完(wan)整無損(sun)，附件(jian)齊全(quan)；⑵手(shou)動(dong)(dong)(dong)旋轉：用(yong)(yong)手(shou)轉動(dong)(dong)(dong)電(dian)(dian)軸(zhou)(zhou)、轉動(dong)(dong)(dong)應(ying)(ying)很(hen)靈活，慣(guan)動(dong)(dong)(dong)量(liang)較好(hao)，軸(zhou)(zhou)向(xiang)基本(ben)無竄動(dong)(dong)(dong)量(liang)；⑶診聽軸(zhou)(zhou)承(cheng)：通電(dian)(dian)運行15-25分鐘，軸(zhou)(zhou)承(cheng)應(ying)(ying)平穩輕快，無停(ting)滯現象。聲(sheng)音均勻和(he)(he)諧；軸(zhou)(zhou)承(cheng)溫度(du)不高，沒有(you)漏油(you)、甩油(you)現象；運行停(ting)止后(hou)，用(yong)(yong)手(shou)摸電(dian)(dian)動(dong)(dong)(dong)機(ji)座(zuo)(zuo)和(he)(he)端(duan)蓋不感到發熱(re)；⑷檢(jian)查(cha)接線(xian)：打(da)開接線(xian)盒(he)看各(ge)相(xiang)相(xiang)線(xian)標(biao)志是否清晰完(wan)整，聯絡片是否壓實壓緊，螺母是否齊全(quan)；⑸測(ce)量(liang)電(dian)(dian)阻：用(yong)(yong)額定(ding)電(dian)(dian)壓500V的手(shou)動(dong)(dong)(dong)式兆歐表，測(ce)量(liang)出線(xian)端(duan)相(xiang)線(xian)與(yu)相(xiang)線(xian)之(zhi)間(jian)及線(xian)對(dui)機(ji)座(zuo)(zuo)之(zhi)間(jian)的絕緣電(dian)(dian)阻，正(zheng)常電(dian)(dian)機(ji)的絕緣電(dian)(dian)阻應(ying)(ying)大于(yu)1兆歐。⑹測(ce)量(liang)電(dian)(dian)流。在(zai)運行中用(yong)(yong)鉗型電(dian)(dian)流表測(ce)電(dian)(dian)機(ji)空載(zai)時(shi)各(ge)相(xiang)的電(dian)(dian)流，三(san)相(xiang)電(dian)(dian)流中任何一(yi)相(xiang)與(yu)三(san)相(xiang)平均值的偏差不得(de)大于(yu)平均值的10%，空載(zai)電(dian)(dian)流一(yi)般(ban)為額定(ding)電(dian)(dian)流的25-50%。

二、電動機的維護。實踐證明，電動機的維護重點在于防止電機燒毀，下述方法是行之有效的：

1、保持(chi)啟(qi)(qi)動設備技術(shu)狀態完好，電動機(ji)(ji)啟(qi)(qi)動設備技術(shu)狀態的(de)好壞直(zhi)接(jie)(jie)關系到能否順利(li)啟(qi)(qi)動。實踐表(biao)明(ming)，絕大多數燒毀(hui)的(de)電動機(ji)(ji)都是啟(qi)(qi)動不順利(li)而(er)燒毀(hui)的(de)，如啟(qi)(qi)動設備技術(shu)狀態不良引發的(de)缺相啟(qi)(qi)動；接(jie)(jie)觸(chu)(chu)(chu)器觸(chu)(chu)(chu)頭(tou)拉(la)弧、打火而(er)導致電壓、電流大幅度改變等。保持(chi)啟(qi)(qi)動設備技術(shu)狀態良好的(de)措(cuo)施(shi)是：經常做檢(jian)查、清(qing)潔、緊固工作。若(ruo)接(jie)(jie)觸(chu)(chu)(chu)器觸(chu)(chu)(chu)頭(tou)不清(qing)潔，氧化燒蝕嚴重，則會(hui)產生(sheng)接(jie)(jie)觸(chu)(chu)(chu)電阻增大，引起發熱、燒蝕觸(chu)(chu)(chu)點(dian)，從而(er)形成缺相運(yun)行(xing)而(er)燒毀(hui)電機(ji)(ji)繞組；接(jie)(jie)觸(chu)(chu)(chu)器吸合線(xian)圈鐵芯有銹蝕和灰塵，會(hui)使吸合不嚴而(er)發出強烈(lie)噪(zao)聲，并增大線(xian)圈電流，直(zhi)至燒毀(hui)線(xian)圈。因(yin)此，電氣控(kong)制(zhi)柜應設在干燥、通風和便(bian)于(yu)操(cao)作的(de)位(wei)置(zhi)；還要(yao)定期除塵、清(qing)理觸(chu)(chu)(chu)點(dian)；線(xian)圈鐵芯要(yao)增加防銹措(cuo)施(shi)；要(yao)經常緊固各連接(jie)(jie)部件；檢(jian)查接(jie)(jie)觸(chu)(chu)(chu)器觸(chu)(chu)(chu)點(dian)，保證接(jie)(jie)觸(chu)(chu)(chu)良好，機(ji)(ji)構動作應靈活、準確(que)，這(zhe)些(xie)是保證啟(qi)(qi)動順利(li)的(de)必然條(tiao)件。

2、保持電(dian)動機(ji)清(qing)潔和(he)良好的冷卻環境(jing)，在(zai)電(dian)動機(ji)的進(jin)風(feng)口處，必須經(jing)常保持清(qing)潔。進(jin)風(feng)口的周(zhou)圍不得有塵土、油污、水漬和(he)其它秸稈雜物，以防(fang)止這類東(dong)西吸(xi)入電(dian)機(ji)內(nei)部，形成(cheng)短路介(jie)質或(huo)損傷電(dian)機(ji)繞組(zu)絕緣(yuan)層；或(huo)阻斷(duan)電(dian)機(ji)的通風(feng)冷卻而溫度升高，導致燒毀。

3、保持電動機(ji)(ji)在(zai)額定(ding)電流(liu)下(xia)工(gong)(gong)作，避免農用電動機(ji)(ji)的(de)過載運行(xing)。當電動機(ji)(ji)處于過載狀態(tai)運行(xing)時，電動機(ji)(ji)轉速下(xia)降(jiang)，電流(liu)增大(da)(da)，溫度(du)(du)升高，繞(rao)組(zu)線圈過熱。其主(zhu)要(yao)(yao)原(yuan)(yuan)因是拖動負(fu)荷過大(da)(da)，電壓過低(di)或被(bei)拖動的(de)機(ji)(ji)械(xie)卡滯(zhi)(zhi)等造成的(de)；若過載時間(jian)稍長，過載電機(ji)(ji)從電網中吸(xi)收大(da)(da)量有功功率，電流(liu)便急劇增加(jia)，隨之溫度(du)(du)上升。在(zai)高溫下(xia)運行(xing)的(de)電機(ji)(ji)，絕緣材料易老化失效(xiao)而燒(shao)毀繞(rao)組(zu)線圈，這是燒(shao)毀電機(ji)(ji)的(de)主(zhu)要(yao)(yao)原(yuan)(yuan)因。因此，一要(yao)(yao)經(jing)常注(zhu)意(yi)檢查機(ji)(ji)組(zu)傳動裝(zhuang)置是否運轉靈活、可(ke)靠，隨時檢查、調(diao)整傳動皮帶松緊度(du)(du)，防止卡滯(zhi)(zhi)；二要(yao)(yao)注(zhu)意(yi)作業機(ji)(ji)械(xie)不(bu)(bu)要(yao)(yao)較(jiao)長時間(jian)超(chao)負(fu)荷工(gong)(gong)作；三要(yao)(yao)保持電壓穩定(ding)，尤其不(bu)(bu)得低(di)壓運轉，從而確保電動機(ji)(ji)在(zai)額定(ding)電流(liu)下(xia)正常工(gong)(gong)作。

4、保(bao)持相(xiang)間電(dian)(dian)流平衡。農(nong)用三相(xiang)異步(bu)電(dian)(dian)動機，其中任(ren)何一相(xiang)的電(dian)(dian)流值與其他兩(liang)相(xiang)電(dian)(dian)流平均值之差不得超過10%，這是保(bao)證電(dian)(dian)動機安全(quan)運轉的必要條件。如果這個差值超過10%，則表明電(dian)(dian)動機已經(jing)出現故(gu)障(zhang)(zhang)，必須立(li)即停(ting)機查明原因，并排(pai)除故(gu)障(zhang)(zhang)后方(fang)能繼續(xu)工(gong)作，否則故(gu)障(zhang)(zhang)會迅(xun)速擴大，直至(zhi)燒毀電(dian)(dian)動機。

5、保(bao)持電(dian)動(dong)(dong)(dong)機(ji)(ji)(ji)(ji)溫(wen)(wen)(wen)度(du)(du)(du)和溫(wen)(wen)(wen)升在正常(chang)范圍內(nei)(nei)。電(dian)機(ji)(ji)(ji)(ji)運(yun)行中(zhong)，要(yao)隨時檢(jian)查軸(zhou)(zhou)承(cheng)(cheng)、定(ding)子、外殼(ke)等部位(wei)的(de)(de)溫(wen)(wen)(wen)度(du)(du)(du)有(you)(you)無(wu)(wu)異常(chang)，特別是對沒有(you)(you)過(guo)載保(bao)護的(de)(de)電(dian)動(dong)(dong)(dong)機(ji)(ji)(ji)(ji)，監視溫(wen)(wen)(wen)度(du)(du)(du)更(geng)為(wei)(wei)重要(yao)。如軸(zhou)(zhou)承(cheng)(cheng)缺油(you)(you)或損(sun)壞，則(ze)必(bi)然引起溫(wen)(wen)(wen)度(du)(du)(du)升高。在軸(zhou)(zhou)承(cheng)(cheng)附近機(ji)(ji)(ji)(ji)體(ti)溫(wen)(wen)(wen)度(du)(du)(du)升高，就(jiu)要(yao)立(li)即停機(ji)(ji)(ji)(ji)檢(jian)查軸(zhou)(zhou)承(cheng)(cheng)，可先加油(you)(you)，若(ruo)仍(reng)然無(wu)(wu)效，則(ze)應拆下軸(zhou)(zhou)承(cheng)(cheng)鑒定(ding)。若(ruo)滾(gun)動(dong)(dong)(dong)體(ti)、滾(gun)道表面有(you)(you)裂(lie)紋、劃傷或損(sun)壞，或間隙變大，內(nei)(nei)環在軸(zhou)(zhou)承(cheng)(cheng)上有(you)(you)轉動(dong)(dong)(dong)，出現任何一項(xiang)，都應更(geng)換(huan)軸(zhou)(zhou)承(cheng)(cheng)。否(fou)則(ze)繼續使(shi)用(yong)會使(shi)軸(zhou)(zhou)承(cheng)(cheng)進一步損(sun)壞，導致(zhi)塌架、電(dian)機(ji)(ji)(ji)(ji)掃膛燒毀(hui)等重大事故。監測電(dian)動(dong)(dong)(dong)機(ji)(ji)(ji)(ji)的(de)(de)溫(wen)(wen)(wen)度(du)(du)(du)或溫(wen)(wen)(wen)升有(you)(you)無(wu)(wu)變化(hua)，可用(yong)下述(shu)簡單方(fang)法(fa)監視：在電(dian)動(dong)(dong)(dong)機(ji)(ji)(ji)(ji)的(de)(de)孔內(nei)(nei)，插支溫(wen)(wen)(wen)度(du)(du)(du)計，用(yong)棉花(hua)團(tuan)塞緊固(gu)定(ding)，便可隨時監視電(dian)動(dong)(dong)(dong)機(ji)(ji)(ji)(ji)溫(wen)(wen)(wen)度(du)(du)(du)的(de)(de)變化(hua)，機(ji)(ji)(ji)(ji)外與殼(ke)內(nei)(nei)溫(wen)(wen)(wen)差(cha)通(tong)常(chang)為(wei)(wei)1℃。

6、及時發現(xian)和(he)處理電(dian)(dian)(dian)機(ji)(ji)(ji)(ji)(ji)異(yi)常，電(dian)(dian)(dian)動(dong)機(ji)(ji)(ji)(ji)(ji)運行中應沒有振動(dong)、噪(zao)聲和(he)異(yi)味(wei)。若出現(xian)振動(dong)，則會(hui)引起電(dian)(dian)(dian)動(dong)機(ji)(ji)(ji)(ji)(ji)相(xiang)連接的負載(zai)作機(ji)(ji)(ji)(ji)(ji)的軸(zhou)心(xin)不同心(xin)度(du)的增大，進而負荷增大，負荷電(dian)(dian)(dian)流也(ye)(ye)隨之增大，導致溫度(du)升高(gao)而燒(shao)毀電(dian)(dian)(dian)機(ji)(ji)(ji)(ji)(ji)。因(yin)此，要經常檢查(cha)引起振動(dong)的地(di)腳(jiao)螺栓、電(dian)(dian)(dian)動(dong)機(ji)(ji)(ji)(ji)(ji)端蓋(gai)、軸(zhou)承壓蓋(gai)等處，不得有松動(dong)，連接裝置必須可靠，尤其對大功率的電(dian)(dian)(dian)機(ji)(ji)(ji)(ji)(ji)，必須及時發現(xian)及時排(pai)除。噪(zao)聲和(he)異(yi)味(wei)是(shi)電(dian)(dian)(dian)機(ji)(ji)(ji)(ji)(ji)運行異(yi)常的重(zhong)要標志，也(ye)(ye)是(shi)重(zhong)大事(shi)故的前兆，必須及時發現(xian)，立即查(cha)明原因(yin)加以排(pai)除，否則延誤(wu)時機(ji)(ji)(ji)(ji)(ji)，擴(kuo)大故障范圍，釀成燒(shao)毀電(dian)(dian)(dian)動(dong)機(ji)(ji)(ji)(ji)(ji)的嚴重(zhong)事(shi)故。