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查看(kan)(kan)外觀：電(dian)動(dong)(dong)機(ji)表(biao)面油(you)漆(qi)層應(ying)光滑平(ping)整(zheng)，銘牌安裝端(duan)(duan)(duan)正，標志齊(qi)全；封閉式電(dian)動(dong)(dong)機(ji)座散熱筋應(ying)完(wan)整(zheng)無損，附件齊(qi)全；⑵手(shou)(shou)動(dong)(dong)旋轉：用(yong)手(shou)(shou)轉動(dong)(dong)電(dian)軸(zhou)、轉動(dong)(dong)應(ying)很靈(ling)活，慣動(dong)(dong)量(liang)(liang)較(jiao)好(hao)，軸(zhou)向基本(ben)無竄動(dong)(dong)量(liang)(liang)；⑶診聽軸(zhou)承：通電(dian)運行15-25分鐘，軸(zhou)承應(ying)平(ping)穩輕(qing)快，無停滯現象(xiang)。聲音均勻和諧；軸(zhou)承溫度不(bu)高，沒有漏油(you)、甩油(you)現象(xiang)；運行停止后，用(yong)手(shou)(shou)摸電(dian)動(dong)(dong)機(ji)座和端(duan)(duan)(duan)蓋不(bu)感(gan)到發熱；⑷檢查接線：打開接線盒看(kan)(kan)各相相線標志是否(fou)清晰完(wan)整(zheng)，聯(lian)絡片是否(fou)壓實壓緊，螺(luo)母(mu)是否(fou)齊(qi)全；⑸測(ce)量(liang)(liang)電(dian)阻(zu)(zu)：用(yong)額定電(dian)壓500V的手(shou)(shou)動(dong)(dong)式兆歐表(biao)，測(ce)量(liang)(liang)出線端(duan)(duan)(duan)相線與(yu)相線之間及線對機(ji)座之間的絕緣(yuan)電(dian)阻(zu)(zu)，正常電(dian)機(ji)的絕緣(yuan)電(dian)阻(zu)(zu)應(ying)大于1兆歐。⑹測(ce)量(liang)(liang)電(dian)流。在運行中用(yong)鉗型(xing)電(dian)流表(biao)測(ce)電(dian)機(ji)空載時各相的電(dian)流，三相電(dian)流中任何一相與(yu)三相平(ping)均值的偏差不(bu)得大于平(ping)均值的10%，空載電(dian)流一般為額定電(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(bao)持啟(qi)(qi)(qi)動(dong)(dong)(dong)(dong)(dong)設備(bei)技術(shu)狀(zhuang)態(tai)完(wan)好，電(dian)(dian)動(dong)(dong)(dong)(dong)(dong)機啟(qi)(qi)(qi)動(dong)(dong)(dong)(dong)(dong)設備(bei)技術(shu)狀(zhuang)態(tai)的好壞直接(jie)關系(xi)到能否順(shun)利(li)啟(qi)(qi)(qi)動(dong)(dong)(dong)(dong)(dong)。實踐(jian)表(biao)明，絕大(da)多(duo)數燒毀的電(dian)(dian)動(dong)(dong)(dong)(dong)(dong)機都是啟(qi)(qi)(qi)動(dong)(dong)(dong)(dong)(dong)不順(shun)利(li)而燒毀的，如啟(qi)(qi)(qi)動(dong)(dong)(dong)(dong)(dong)設備(bei)技術(shu)狀(zhuang)態(tai)不良引(yin)發(fa)的缺(que)相(xiang)啟(qi)(qi)(qi)動(dong)(dong)(dong)(dong)(dong)；接(jie)觸(chu)(chu)(chu)器觸(chu)(chu)(chu)頭拉(la)弧、打(da)火而導致(zhi)電(dian)(dian)壓、電(dian)(dian)流大(da)幅(fu)度改變等。保(bao)持啟(qi)(qi)(qi)動(dong)(dong)(dong)(dong)(dong)設備(bei)技術(shu)狀(zhuang)態(tai)良好的措施是：經常做檢查、清潔、緊固工作(zuo)。若接(jie)觸(chu)(chu)(chu)器觸(chu)(chu)(chu)頭不清潔，氧化燒蝕(shi)嚴(yan)重，則會產生(sheng)接(jie)觸(chu)(chu)(chu)電(dian)(dian)阻增(zeng)(zeng)大(da)，引(yin)起發(fa)熱、燒蝕(shi)觸(chu)(chu)(chu)點(dian)，從而形成(cheng)缺(que)相(xiang)運(yun)行而燒毀電(dian)(dian)機繞組(zu)；接(jie)觸(chu)(chu)(chu)器吸合線圈(quan)鐵(tie)芯有銹(xiu)蝕(shi)和灰(hui)塵(chen)，會使(shi)吸合不嚴(yan)而發(fa)出強(qiang)烈噪聲，并(bing)增(zeng)(zeng)大(da)線圈(quan)電(dian)(dian)流，直至(zhi)燒毀線圈(quan)。因此，電(dian)(dian)氣控制柜應(ying)設在干燥、通(tong)風(feng)和便(bian)于操作(zuo)的位置；還要定期除塵(chen)、清理觸(chu)(chu)(chu)點(dian)；線圈(quan)鐵(tie)芯要增(zeng)(zeng)加防銹(xiu)措施；要經常緊固各(ge)連接(jie)部件；檢查接(jie)觸(chu)(chu)(chu)器觸(chu)(chu)(chu)點(dian)，保(bao)證接(jie)觸(chu)(chu)(chu)良好，機構動(dong)(dong)(dong)(dong)(dong)作(zuo)應(ying)靈活(huo)、準確，這(zhe)些是保(bao)證啟(qi)(qi)(qi)動(dong)(dong)(dong)(dong)(dong)順(shun)利(li)的必然條件。

2、保持電(dian)動機(ji)清(qing)潔(jie)和良好(hao)的冷卻環境，在電(dian)動機(ji)的進風口處(chu)，必(bi)須經常保持清(qing)潔(jie)。進風口的周圍不得有(you)塵土(tu)、油污、水漬和其(qi)它秸稈雜(za)物，以防止這類(lei)東西吸入電(dian)機(ji)內(nei)部，形成(cheng)短(duan)路介質或(huo)損傷電(dian)機(ji)繞組絕緣層；或(huo)阻斷電(dian)機(ji)的通風冷卻而溫(wen)度升高，導致(zhi)燒毀。

3、保持(chi)(chi)電(dian)(dian)(dian)動(dong)(dong)機(ji)在(zai)額定電(dian)(dian)(dian)流(liu)下工(gong)作，避(bi)免農(nong)用電(dian)(dian)(dian)動(dong)(dong)機(ji)的過載運(yun)行。當電(dian)(dian)(dian)動(dong)(dong)機(ji)處(chu)于過載狀態運(yun)行時(shi)，電(dian)(dian)(dian)動(dong)(dong)機(ji)轉速(su)下降，電(dian)(dian)(dian)流(liu)增大(da)(da)，溫度升高(gao)，繞組(zu)(zu)線圈過熱。其主要原因(yin)是拖動(dong)(dong)負荷過大(da)(da)，電(dian)(dian)(dian)壓過低(di)或被(bei)拖動(dong)(dong)的機(ji)械(xie)卡滯等造成的；若過載時(shi)間稍長(chang)(chang)，過載電(dian)(dian)(dian)機(ji)從(cong)電(dian)(dian)(dian)網中(zhong)吸收大(da)(da)量有功功率，電(dian)(dian)(dian)流(liu)便急劇增加，隨(sui)之溫度上升。在(zai)高(gao)溫下運(yun)行的電(dian)(dian)(dian)機(ji)，絕緣材料易(yi)老(lao)化失效而燒毀(hui)繞組(zu)(zu)線圈，這是燒毀(hui)電(dian)(dian)(dian)機(ji)的主要原因(yin)。因(yin)此，一要經常注意檢查機(ji)組(zu)(zu)傳動(dong)(dong)裝置(zhi)是否運(yun)轉靈活、可靠，隨(sui)時(shi)檢查、調(diao)整(zheng)傳動(dong)(dong)皮帶(dai)松緊度，防止卡滯；二要注意作業(ye)機(ji)械(xie)不要較長(chang)(chang)時(shi)間超(chao)負荷工(gong)作；三要保持(chi)(chi)電(dian)(dian)(dian)壓穩定，尤(you)其不得低(di)壓運(yun)轉，從(cong)而確保電(dian)(dian)(dian)動(dong)(dong)機(ji)在(zai)額定電(dian)(dian)(dian)流(liu)下正常工(gong)作。

4、保(bao)持相間電(dian)流平衡。農用三相異(yi)步電(dian)動機(ji)，其中任何一相的電(dian)流值(zhi)(zhi)與其他兩相電(dian)流平均值(zhi)(zhi)之(zhi)差(cha)不得超(chao)過10%，這(zhe)(zhe)是保(bao)證電(dian)動機(ji)安全運(yun)轉的必要條件。如果(guo)這(zhe)(zhe)個差(cha)值(zhi)(zhi)超(chao)過10%，則表明(ming)電(dian)動機(ji)已經出現故障(zhang)，必須(xu)立即停機(ji)查(cha)明(ming)原因，并排除故障(zhang)后方能繼續(xu)工作，否(fou)則故障(zhang)會迅速擴大，直至燒毀電(dian)動機(ji)。

5、保持電(dian)動(dong)機(ji)(ji)溫(wen)(wen)度和溫(wen)(wen)升(sheng)在(zai)(zai)正常范圍(wei)內。電(dian)機(ji)(ji)運(yun)行中，要隨時檢查軸(zhou)承(cheng)、定子、外(wai)殼等部位的溫(wen)(wen)度有(you)(you)無(wu)異常，特別是對沒有(you)(you)過載(zai)保護(hu)的電(dian)動(dong)機(ji)(ji)，監視(shi)溫(wen)(wen)度更(geng)為重(zhong)要。如軸(zhou)承(cheng)缺油或損壞(huai)，則必然引(yin)起(qi)溫(wen)(wen)度升(sheng)高。在(zai)(zai)軸(zhou)承(cheng)附近(jin)機(ji)(ji)體(ti)溫(wen)(wen)度升(sheng)高，就要立即停機(ji)(ji)檢查軸(zhou)承(cheng)，可(ke)先加油，若(ruo)仍然無(wu)效，則應拆(chai)下軸(zhou)承(cheng)鑒定。若(ruo)滾(gun)動(dong)體(ti)、滾(gun)道表(biao)面有(you)(you)裂紋、劃傷或損壞(huai)，或間隙變大(da)，內環在(zai)(zai)軸(zhou)承(cheng)上(shang)有(you)(you)轉動(dong)，出現任何一(yi)項，都應更(geng)換軸(zhou)承(cheng)。否則繼(ji)續使(shi)用會使(shi)軸(zhou)承(cheng)進一(yi)步損壞(huai)，導致塌架、電(dian)機(ji)(ji)掃膛燒毀等重(zhong)大(da)事故(gu)。監測電(dian)動(dong)機(ji)(ji)的溫(wen)(wen)度或溫(wen)(wen)升(sheng)有(you)(you)無(wu)變化(hua)，可(ke)用下述簡單方法監視(shi)：在(zai)(zai)電(dian)動(dong)機(ji)(ji)的孔內，插支(zhi)溫(wen)(wen)度計，用棉花團塞緊固定，便(bian)可(ke)隨時監視(shi)電(dian)動(dong)機(ji)(ji)溫(wen)(wen)度的變化(hua)，機(ji)(ji)外(wai)與殼內溫(wen)(wen)差(cha)通常為1℃。

6、及(ji)時(shi)發現(xian)(xian)和(he)處理電(dian)(dian)(dian)機(ji)異(yi)常(chang)(chang)，電(dian)(dian)(dian)動(dong)機(ji)運行中應沒有振動(dong)、噪聲和(he)異(yi)味。若出現(xian)(xian)振動(dong)，則會引(yin)起(qi)電(dian)(dian)(dian)動(dong)機(ji)相連接(jie)的(de)(de)負載(zai)作機(ji)的(de)(de)軸(zhou)心不同心度(du)的(de)(de)增大，進(jin)而負荷增大，負荷電(dian)(dian)(dian)流也隨之增大，導(dao)致溫度(du)升(sheng)高而燒(shao)毀(hui)電(dian)(dian)(dian)機(ji)。因此，要經常(chang)(chang)檢查引(yin)起(qi)振動(dong)的(de)(de)地腳螺栓、電(dian)(dian)(dian)動(dong)機(ji)端(duan)蓋、軸(zhou)承壓蓋等處，不得有松(song)動(dong)，連接(jie)裝置必(bi)須可靠，尤其(qi)對(dui)大功率的(de)(de)電(dian)(dian)(dian)機(ji)，必(bi)須及(ji)時(shi)發現(xian)(xian)及(ji)時(shi)排(pai)除。噪聲和(he)異(yi)味是電(dian)(dian)(dian)機(ji)運行異(yi)常(chang)(chang)的(de)(de)重要標志，也是重大事故(gu)(gu)的(de)(de)前兆(zhao)，必(bi)須及(ji)時(shi)發現(xian)(xian)，立即(ji)查明原因加以排(pai)除，否則延誤時(shi)機(ji)，擴大故(gu)(gu)障范圍，釀成燒(shao)毀(hui)電(dian)(dian)(dian)動(dong)機(ji)的(de)(de)嚴重事故(gu)(gu)。