冷庫壓縮機常見的故障及處理方法

一、電機燒毀

電動機壓縮機（以下簡(jian)稱壓縮機）的故障可(ke)分為電機故障和(he)機械故障（包括曲軸，連桿，活(huo)塞，閥(fa)片(pian)，缸(gang)蓋墊等）。

機械故障往往使電(dian)機超負荷運轉甚至堵轉，是電(dian)機損壞的主(zhu)要原因之一。

電(dian)機的(de)損(sun)壞主(zhu)要表現(xian)(xian)為定(ding)(ding)子(zi)繞(rao)(rao)組絕(jue)緣(yuan)(yuan)層破壞（短(duan)路）和(he)斷路等。定(ding)(ding)子(zi)繞(rao)(rao)組損(sun)壞后很難及時被發現(xian)(xian)，最終可(ke)能導致繞(rao)(rao)組燒毀。繞(rao)(rao)組燒毀后，掩蓋了一些導致燒毀的(de)現(xian)(xian)象或直接(jie)原因(yin)(yin)，使得事(shi)后分析和(he)原因(yin)(yin)調查比(bi)較困難。然而，電(dian)機的(de)運轉(zhuan)離不開正常的(de)電(dian)源輸入，合理的(de)電(dian)機負(fu)荷，良好(hao)的(de)散熱和(he)繞(rao)(rao)組漆包(bao)線絕(jue)緣(yuan)(yuan)層的(de)保護(hu)。

從這幾方面入手，不(bu)難發現(xian)繞組燒(shao)毀(hui)的原因不(bu)外乎如下六(liu)種：

(1)異常負荷和堵轉；

(2)金屬屑(xie)引起的(de)繞(rao)組短路(lu)；

(3)接觸器問題；

(4)電源缺(que)相和電壓異常；

(5)冷(leng)卻不足；

(6)用(yong)壓縮(suo)機抽真空。

實際(ji)上(shang)，多種因素共(gong)同促成(cheng)的電機損壞更為常見。

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二、異常負荷和堵轉

電機負(fu)荷包括(kuo)壓縮氣(qi)體所(suo)需(xu)(xu)負(fu)荷以及克服機械摩擦所(suo)需(xu)(xu)負(fu)荷。

壓比過大，或壓差過大，會使壓縮過程更為困難；而潤滑失效引起的摩擦阻力增加，以及極端情況下的電機堵轉，將大大增加電機負荷。潤滑失效，摩擦阻力增大，是負荷異常的首要原因。回液稀釋潤滑油，潤滑油(you)(you)過(guo)熱(re)，潤滑油(you)(you)焦(jiao)化(hua)變質，以及(ji)缺(que)油(you)(you)等(deng)都會破壞正常(chang)潤滑，導致潤滑失(shi)效。回(hui)液稀釋潤滑油(you)(you)，影響摩擦(ca)面(mian)正常(chang)油(you)(you)膜(mo)(mo)(mo)的形成，甚至(zhi)沖刷(shua)掉原有(you)油(you)(you)膜(mo)(mo)(mo)，增加(jia)摩擦(ca)和磨(mo)損。壓縮機過(guo)熱(re)會引(yin)起(qi)使(shi)(shi)潤滑油(you)(you)高溫(wen)變稀甚至(zhi)焦(jiao)化(hua)，影響正常(chang)油(you)(you)膜(mo)(mo)(mo)的形成。系統回(hui)油(you)(you)不(bu)好(hao)，壓縮機缺(que)油(you)(you)，自然無法(fa)維持正常(chang)潤滑。曲軸高速(su)旋轉，連桿活塞(sai)等(deng)高速(su)運動，沒有(you)油(you)(you)膜(mo)(mo)(mo)保(bao)護的摩擦(ca)面(mian)會迅速(su)升溫(wen)，局(ju)部(bu)高溫(wen)使(shi)(shi)潤滑油(you)(you)迅速(su)蒸(zheng)發或(huo)焦(jiao)化(hua)，使(shi)(shi)該部(bu)位潤滑更加(jia)困難，數秒鐘內可引(yin)起(qi)局(ju)部(bu)嚴重磨(mo)損。潤滑失(shi)效，局(ju)部(bu)磨(mo)損，使(shi)(shi)曲軸轉動需要更大力(li)矩。

小功(gong)率壓(ya)縮(suo)機(ji)（如冰(bing)箱(xiang)，家用(yong)空調壓(ya)縮(suo)機(ji)）由于電(dian)機(ji)扭矩小，潤滑(hua)失效后常(chang)出(chu)現堵(du)(du)(du)轉(zhuan)(zhuan)（電(dian)機(ji)無法轉(zhuan)(zhuan)動(dong)）現象，并進(jin)入“堵(du)(du)(du)轉(zhuan)(zhuan)－熱(re)保護(hu)－堵(du)(du)(du)轉(zhuan)(zhuan)”死循(xun)環，電(dian)機(ji)燒(shao)毀只是時(shi)間(jian)問題。而(er)大(da)(da)(da)功(gong)率半封閉壓(ya)縮(suo)機(ji)電(dian)機(ji)扭矩很(hen)(hen)大(da)(da)(da)，局部磨(mo)損(sun)不(bu)會(hui)(hui)引(yin)(yin)(yin)起(qi)堵(du)(du)(du)轉(zhuan)(zhuan)，電(dian)機(ji)功(gong)率會(hui)(hui)在一(yi)定(ding)范圍內隨(sui)(sui)負(fu)荷(he)(he)而(er)增大(da)(da)(da)，從而(er)引(yin)(yin)(yin)起(qi)更為嚴重(zhong)的(de)磨(mo)損(sun)，甚至引(yin)(yin)(yin)起(qi)咬(yao)缸(gang)（活塞(sai)卡在氣(qi)缸(gang)內），連桿斷裂(lie)等(deng)嚴重(zhong)損(sun)壞。堵(du)(du)(du)轉(zhuan)(zhuan)時(shi)的(de)電(dian)流（堵(du)(du)(du)轉(zhuan)(zhuan)電(dian)流）大(da)(da)(da)約(yue)是正常(chang)運行電(dian)流的(de)4－8倍。電(dian)機(ji)啟動(dong)瞬間(jian)，電(dian)流的(de)峰值可接近(jin)或達到堵(du)(du)(du)轉(zhuan)(zhuan)電(dian)流。由于電(dian)阻(zu)放(fang)熱(re)量與電(dian)流的(de)平(ping)方成(cheng)正比(bi)，啟動(dong)和(he)堵(du)(du)(du)轉(zhuan)(zhuan)時(shi)的(de)電(dian)流會(hui)(hui)使(shi)(shi)繞(rao)組迅速(su)升(sheng)溫(wen)。熱(re)保護(hu)可以在堵(du)(du)(du)轉(zhuan)(zhuan)時(shi)保護(hu)電(dian)極，但(dan)一(yi)般不(bu)會(hui)(hui)有很(hen)(hen)快的(de)響應，不(bu)能阻(zu)止頻繁啟動(dong)等(deng)引(yin)(yin)(yin)起(qi)的(de)繞(rao)組溫(wen)度變化。頻繁啟動(dong)和(he)異(yi)常(chang)負(fu)荷(he)(he)，使(shi)(shi)繞(rao)組經受高溫(wen)考驗，會(hui)(hui)降低(di)漆包線的(de)絕(jue)緣(yuan)性能。此(ci)外，壓(ya)縮(suo)氣(qi)體所(suo)需負(fu)荷(he)(he)也會(hui)(hui)隨(sui)(sui)壓(ya)縮(suo)比(bi)增大(da)(da)(da)和(he)壓(ya)差增大(da)(da)(da)而(er)增大(da)(da)(da)。

因(yin)此將高溫(wen)壓(ya)(ya)縮機用(yong)(yong)于(yu)低溫(wen)，或將低溫(wen)壓(ya)(ya)縮機用(yong)(yong)于(yu)高溫(wen)，都會影響(xiang)電(dian)(dian)機負荷和散熱，是不合(he)(he)適(shi)的，會縮短電(dian)(dian)極(ji)使用(yong)(yong)壽命(ming)。繞組絕緣性能變差后，如果有其它因(yin)素（如金屬(shu)屑構(gou)成導電(dian)(dian)回路(lu)，酸性潤(run)滑油等）配合(he)(he)，很(hen)容易引起短路(lu)而損(sun)壞。

三、金屬屑引起的繞組短路

繞組中夾雜的(de)金屬屑是短路和接地絕緣值低的(de)罪(zui)魁禍首。

壓縮機運轉時(shi)的(de)(de)(de)正常振動，以及(ji)(ji)每次啟動時(shi)繞(rao)組(zu)(zu)受電磁力(li)作用而扭動，都(dou)會(hui)促使夾雜于繞(rao)組(zu)(zu)間(jian)的(de)(de)(de)金(jin)屬(shu)(shu)屑(xie)(xie)與繞(rao)組(zu)(zu)漆包(bao)線(xian)之間(jian)的(de)(de)(de)相對(dui)運動和(he)摩擦。棱角銳利(li)的(de)(de)(de)金(jin)屬(shu)(shu)屑(xie)(xie)會(hui)劃(hua)傷漆包(bao)線(xian)絕緣層，引起短路(lu)(lu)。金(jin)屬(shu)(shu)屑(xie)(xie)的(de)(de)(de)來源包(bao)括施(shi)工(gong)時(shi)留下(xia)的(de)(de)(de)銅(tong)管(guan)(guan)屑(xie)(xie)，焊渣(zha)，壓(ya)(ya)(ya)(ya)(ya)縮(suo)(suo)機(ji)(ji)內部磨損(sun)和(he)零(ling)部件損(sun)壞（比(bi)如閥片破碎(sui)）時(shi)掉下(xia)的(de)(de)(de)金(jin)屬(shu)(shu)屑(xie)(xie)等。對(dui)于全(quan)封閉壓(ya)(ya)(ya)(ya)(ya)縮(suo)(suo)機(ji)(ji)（包(bao)括全(quan)封閉渦旋壓(ya)(ya)(ya)(ya)(ya)縮(suo)(suo)機(ji)(ji)），這(zhe)些金(jin)屬(shu)(shu)屑(xie)(xie)或(huo)碎(sui)粒會(hui)落(luo)(luo)在繞(rao)組(zu)(zu)上。對(dui)于半(ban)封閉壓(ya)(ya)(ya)(ya)(ya)縮(suo)(suo)機(ji)(ji)，有些顆粒會(hui)隨氣(qi)體和(he)潤滑(hua)油在系統中(zhong)流(liu)動，最后(hou)(hou)由于磁性聚(ju)(ju)集在繞(rao)組(zu)(zu)中(zhong)；而有些金(jin)屬(shu)(shu)屑(xie)(xie)（比(bi)如軸承磨損(sun)以及(ji)(ji)電機(ji)(ji)轉子與定子磨損(sun)（掃膛）時(shi)產生(sheng)的(de)(de)(de)）會(hui)直接(jie)落(luo)(luo)在繞(rao)組(zu)(zu)上。繞(rao)組(zu)(zu)中(zhong)聚(ju)(ju)集了金(jin)屬(shu)(shu)屑(xie)(xie)后(hou)(hou)，發(fa)生(sheng)短路(lu)(lu)只是(shi)一個時(shi)間(jian)問題。需要(yao)特(te)別提(ti)請(qing)注意(yi)的(de)(de)(de)是(shi)雙(shuang)(shuang)級(ji)(ji)(ji)壓(ya)(ya)(ya)(ya)(ya)縮(suo)(suo)機(ji)(ji)。在雙(shuang)(shuang)級(ji)(ji)(ji)壓(ya)(ya)(ya)(ya)(ya)縮(suo)(suo)機(ji)(ji)中(zhong)，回氣(qi)以及(ji)(ji)正常的(de)(de)(de)回油直接(jie)進(jin)入第(di)一級(ji)(ji)(ji)（低壓(ya)(ya)(ya)(ya)(ya)級(ji)(ji)(ji)）氣(qi)缸(gang)，壓(ya)(ya)(ya)(ya)(ya)縮(suo)(suo)后(hou)(hou)經(jing)中(zhong)壓(ya)(ya)(ya)(ya)(ya)管(guan)(guan)進(jin)入電機(ji)(ji)腔冷卻繞(rao)組(zu)(zu)，然(ran)后(hou)(hou)和(he)普通單級(ji)(ji)(ji)壓(ya)(ya)(ya)(ya)(ya)縮(suo)(suo)機(ji)(ji)一樣，進(jin)入第(di)二級(ji)(ji)(ji)（高壓(ya)(ya)(ya)(ya)(ya)級(ji)(ji)(ji)氣(qi)缸(gang)）。回氣(qi)中(zhong)帶(dai)有潤滑(hua)油，已經(jing)使壓(ya)(ya)(ya)(ya)(ya)縮(suo)(suo)過程如履(lv)薄冰，如果(guo)再有回液，第(di)一級(ji)(ji)(ji)氣(qi)缸(gang)的(de)(de)(de)閥片很(hen)容易被打碎(sui)。碎(sui)閥片經(jing)中(zhong)壓(ya)(ya)(ya)(ya)(ya)管(guan)(guan)后(hou)(hou)可(ke)進(jin)入繞(rao)組(zu)(zu)。因此，雙(shuang)(shuang)級(ji)(ji)(ji)壓(ya)(ya)(ya)(ya)(ya)縮(suo)(suo)機(ji)(ji)比(bi)單級(ji)(ji)(ji)壓(ya)(ya)(ya)(ya)(ya)縮(suo)(suo)機(ji)(ji)更容易出現金(jin)屬(shu)(shu)屑(xie)(xie)引起的(de)(de)(de)電機(ji)(ji)短路(lu)(lu)。

不幸的(de)(de)事(shi)情往往湊到(dao)一塊(kuai)，出(chu)問題的(de)(de)壓縮機在開(kai)機分析時(shi)聞道的(de)(de)常(chang)常(chang)是(shi)潤(run)(run)滑油的(de)(de)焦糊味(wei)。金屬(shu)面嚴重磨損時(shi)溫度是(shi)很高的(de)(de)，而潤(run)(run)滑油在175?C以上時(shi)開(kai)始(shi)焦化。系(xi)統中如果有較多水分（真(zhen)空(kong)抽得不理想，潤(run)(run)滑油和制冷(leng)劑(ji)含(han)水量大，負壓回氣(qi)管(guan)破裂后空(kong)氣(qi)進入等），潤(run)(run)滑油就(jiu)可能出(chu)現(xian)酸性(xing)(xing)。酸性(xing)(xing)潤(run)(run)滑油會(hui)腐蝕銅(tong)管(guan)和繞(rao)組絕緣(yuan)層，一方(fang)面，它會(hui)引起鍍銅(tong)現(xian)象(xiang)；另一方(fang)面，這(zhe)種含(han)有銅(tong)原子的(de)(de)酸性(xing)(xing)潤(run)(run)滑油的(de)(de)絕緣(yuan)性(xing)(xing)能很差，為(wei)繞(rao)組短路提供(gong)了條件。

四、接觸器問題

接觸器是電機控制回路中重要部件之(zhi)一，選型(xing)不合(he)理可以毀壞最好的壓縮機。

按負載正(zheng)確選擇接(jie)觸器(qi)是(shi)極其重要的。接(jie)觸器(qi)必(bi)須(xu)能滿(man)足苛刻(ke)的條件，如快速循環，持續超(chao)載和低(di)電壓。它們必(bi)須(xu)有足夠大(da)的面積以散發(fa)負載電流所(suo)產(chan)生的熱(re)量，觸點材料的選擇必(bi)須(xu)在(zai)啟動或堵轉(zhuan)等大(da)電流情況下能防止焊合。為了(le)安全可靠，壓縮機接(jie)觸器(qi)要同時(shi)斷(duan)開(kai)三相(xiang)電路。谷輪(lun)公(gong)司(si)不推薦斷(duan)開(kai)二相(xiang)電路的方(fang)法。在(zai)美國，谷輪(lun)公(gong)司(si)認可的接(jie)觸器(qi)必(bi)須(xu)滿(man)足如下四項：

接(jie)觸器(qi)必須(xu)滿足ARI標準780-78“專用接(jie)觸器(qi)標準”規定的工作和測試(shi)準則。

制造(zao)商(shang)必須保證接觸器在室(shi)溫下，在最低銘牌電壓(ya)的80％時能閉(bi)合。

當使用單個接觸器(qi)時(shi)，接觸器(qi)額(e)定(ding)電流(liu)必(bi)須大于電機銘牌電流(liu)額(e)定(ding)值(RLA).同(tong)時(shi)，接觸器(qi)必(bi)須能承受電機堵轉電流(liu)。如果接觸器(qi)下游(you)還有其它負載(zai)，比如電機風扇(shan)等，也(ye)必(bi)須考慮。

當使用兩個(ge)接觸器時，每個(ge)接觸器的分繞組(zu)堵轉額定值必須等(deng)于或大(da)于壓縮(suo)機半繞組(zu)堵轉額定值。

接觸器的(de)額定(ding)電流不能低于壓縮機銘牌上的(de)額定(ding)電流。

規格小(xiao)(xiao)或質(zhi)量低(di)劣的(de)(de)(de)接(jie)觸(chu)器(qi)(qi)無(wu)法經受(shou)壓(ya)縮機(ji)(ji)(ji)啟(qi)(qi)動(dong)(dong)，堵轉和(he)(he)(he)低(di)電壓(ya)時的(de)(de)(de)大電流沖(chong)擊，容(rong)易(yi)出現單(dan)相(xiang)或多相(xiang)觸(chu)點抖動(dong)(dong),焊接(jie)甚至脫(tuo)落的(de)(de)(de)現象，引起(qi)電機(ji)(ji)(ji)損(sun)壞(huai)。觸(chu)點抖動(dong)(dong)的(de)(de)(de)接(jie)觸(chu)器(qi)(qi)頻繁地啟(qi)(qi)停電機(ji)(ji)(ji)。電機(ji)(ji)(ji)頻繁啟(qi)(qi)動(dong)(dong)，巨大的(de)(de)(de)啟(qi)(qi)動(dong)(dong)電流和(he)(he)(he)發熱,會加劇(ju)繞(rao)組(zu)絕緣層(ceng)的(de)(de)(de)老化。每(mei)次(ci)啟(qi)(qi)動(dong)(dong)時，磁性(xing)力(li)矩使(shi)電機(ji)(ji)(ji)繞(rao)組(zu)有(you)微小(xiao)(xiao)的(de)(de)(de)移動(dong)(dong)和(he)(he)(he)相(xiang)互摩擦。如(ru)(ru)果有(you)其它(ta)因素配(pei)合（如(ru)(ru)金(jin)屬屑，絕緣性(xing)差的(de)(de)(de)潤滑油等），很容(rong)易(yi)引起(qi)繞(rao)組(zu)間短路。熱保(bao)護系統并(bing)未設計成(cheng)能防止這種(zhong)毀壞(huai)。此(ci)外，抖動(dong)(dong)的(de)(de)(de)接(jie)觸(chu)器(qi)(qi)線(xian)圈容(rong)易(yi)失效。如(ru)(ru)果有(you)接(jie)觸(chu)線(xian)圈損(sun)壞(huai)，容(rong)易(yi)出現單(dan)相(xiang)狀態。

如果接觸(chu)(chu)(chu)器(qi)選型偏(pian)小，觸(chu)(chu)(chu)頭不(bu)能承受(shou)電弧(hu)和(he)由于頻繁開(kai)停循環或不(bu)穩定控(kong)制回路電壓(ya)產生的(de)高溫，可能焊(han)(han)合或從觸(chu)(chu)(chu)頭架中(zhong)脫落。焊(han)(han)合的(de)觸(chu)(chu)(chu)頭將產生永久性(xing)單相(xiang)狀(zhuang)(zhuang)態，使過載保護(hu)(hu)器(qi)持(chi)續地(di)循環接通(tong)和(he)斷開(kai)，需要特別強調(diao)的(de)是，接觸(chu)(chu)(chu)器(qi)觸(chu)(chu)(chu)點焊(han)(han)合后，依(yi)賴接觸(chu)(chu)(chu)器(qi)斷開(kai)壓(ya)縮機(ji)電源回路的(de)所有控(kong)制（比如高低壓(ya)控(kong)制，油壓(ya)控(kong)制，融(rong)霜控(kong)制等）將全(quan)部(bu)失效，壓(ya)縮機(ji)處(chu)于無(wu)保護(hu)(hu)狀(zhuang)(zhuang)態。

因(yin)此，當電機燒毀后，檢查接觸器(qi)是(shi)必不可少的(de)工序。接觸器(qi)是(shi)導致(zhi)電機損壞的(de)一個(ge)常(chang)常(chang)被人遺忘的(de)重要原因(yin)。

五、電源缺相和電壓異常

電壓(ya)不正常和缺相(xiang)可(ke)以輕而易舉地毀掉任何電機(ji)。

電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)變化范圍(wei)不(bu)(bu)(bu)(bu)能(neng)超(chao)過(guo)(guo)額定電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)的(de)(de)(de)±10%。三(san)(san)相(xiang)間的(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)不(bu)(bu)(bu)(bu)平(ping)(ping)(ping)(ping)(ping)(ping)衡(heng)(heng)(heng)(heng)不(bu)(bu)(bu)(bu)能(neng)超(chao)過(guo)(guo)5％。大(da)(da)(da)功率電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)(ji)必(bi)(bi)須獨立供電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)，以(yi)防同線其他大(da)(da)(da)功率設(she)備啟動(dong)(dong)和運轉(zhuan)(zhuan)時(shi)造成(cheng)低(di)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)。電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)(ji)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源線必(bi)(bi)須能(neng)夠承(cheng)載電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)(ji)的(de)(de)(de)額定電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流。如果(guo)(guo)發(fa)生缺相(xiang)時(shi)壓(ya)(ya)(ya)(ya)(ya)縮機(ji)(ji)(ji)正(zheng)在運轉(zhuan)(zhuan)，它將繼續運行(xing)但會(hui)(hui)有(you)(you)大(da)(da)(da)的(de)(de)(de)負載電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流。電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)(ji)繞(rao)組(zu)(zu)會(hui)(hui)很快過(guo)(guo)熱，正(zheng)常情況下壓(ya)(ya)(ya)(ya)(ya)縮機(ji)(ji)(ji)會(hui)(hui)被熱保(bao)護(hu)。當(dang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)(ji)繞(rao)組(zu)(zu)冷卻至(zhi)設(she)定溫度，接觸(chu)器會(hui)(hui)閉合(he)，但壓(ya)(ya)(ya)(ya)(ya)縮機(ji)(ji)(ji)啟動(dong)(dong)不(bu)(bu)(bu)(bu)起來，出(chu)現(xian)堵轉(zhuan)(zhuan)，并進入(ru)“堵轉(zhuan)(zhuan)－熱保(bao)護(hu)－堵轉(zhuan)(zhuan)”死循(xun)環。現(xian)代電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)(ji)繞(rao)組(zu)(zu)的(de)(de)(de)差別非常小(xiao)，電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源三(san)(san)相(xiang)平(ping)(ping)(ping)(ping)(ping)(ping)衡(heng)(heng)(heng)(heng)時(shi)相(xiang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流的(de)(de)(de)差別可(ke)以(yi)忽略。理想狀態下，相(xiang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)始終相(xiang)等，只要在任一相(xiang)上接一個(ge)(ge)保(bao)護(hu)器就可(ke)以(yi)防止(zhi)過(guo)(guo)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流造成(cheng)的(de)(de)(de)損(sun)壞(huai)。實(shi)際(ji)上很難保(bao)證(zheng)相(xiang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)的(de)(de)(de)平(ping)(ping)(ping)(ping)(ping)(ping)衡(heng)(heng)(heng)(heng)。電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)不(bu)(bu)(bu)(bu)平(ping)(ping)(ping)(ping)(ping)(ping)衡(heng)(heng)(heng)(heng)百(bai)(bai)分(fen)數(shu)(shu)計算方法為(wei)，相(xiang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)與(yu)三(san)(san)相(xiang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)平(ping)(ping)(ping)(ping)(ping)(ping)均值(zhi)的(de)(de)(de)最(zui)大(da)(da)(da)偏差值(zhi)與(yu)三(san)(san)相(xiang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)平(ping)(ping)(ping)(ping)(ping)(ping)均值(zhi)比(bi)值(zhi)。例(li)如，標稱380V三(san)(san)相(xiang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源，在壓(ya)(ya)(ya)(ya)(ya)縮機(ji)(ji)(ji)接線端測量的(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)分(fen)別為(wei)380V、366V、400V。可(ke)以(yi)計算出(chu)三(san)(san)相(xiang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)平(ping)(ping)(ping)(ping)(ping)(ping)均值(zhi)382V，最(zui)大(da)(da)(da)偏差為(wei)20V,所以(yi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)不(bu)(bu)(bu)(bu)平(ping)(ping)(ping)(ping)(ping)(ping)衡(heng)(heng)(heng)(heng)百(bai)(bai)分(fen)數(shu)(shu)為(wei)5.2％。作(zuo)為(wei)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)不(bu)(bu)(bu)(bu)平(ping)(ping)(ping)(ping)(ping)(ping)衡(heng)(heng)(heng)(heng)的(de)(de)(de)結(jie)果(guo)(guo)，在正(zheng)常運行(xing)使(shi)負載電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流的(de)(de)(de)不(bu)(bu)(bu)(bu)平(ping)(ping)(ping)(ping)(ping)(ping)衡(heng)(heng)(heng)(heng)是(shi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)不(bu)(bu)(bu)(bu)平(ping)(ping)(ping)(ping)(ping)(ping)衡(heng)(heng)(heng)(heng)百(bai)(bai)分(fen)點數(shu)(shu)的(de)(de)(de)4－10倍(bei)。前例(li)中，5.2％不(bu)(bu)(bu)(bu)平(ping)(ping)(ping)(ping)(ping)(ping)衡(heng)(heng)(heng)(heng)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)可(ke)能(neng)引起50％的(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流不(bu)(bu)(bu)(bu)平(ping)(ping)(ping)(ping)(ping)(ping)衡(heng)(heng)(heng)(heng)。美國(guo)(guo)國(guo)(guo)家電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)器制造商協會(hui)(hui)(NEMA)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)動(dong)(dong)機(ji)(ji)(ji)和發(fa)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)(ji)標準(zhun)出(chu)版物指出(chu)，由不(bu)(bu)(bu)(bu)平(ping)(ping)(ping)(ping)(ping)(ping)衡(heng)(heng)(heng)(heng)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)造成(cheng)的(de)(de)(de)相(xiang)繞(rao)組(zu)(zu)溫升百(bai)(bai)分(fen)比(bi)大(da)(da)(da)約是(shi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)不(bu)(bu)(bu)(bu)平(ping)(ping)(ping)(ping)(ping)(ping)衡(heng)(heng)(heng)(heng)百(bai)(bai)分(fen)點數(shu)(shu)平(ping)(ping)(ping)(ping)(ping)(ping)方的(de)(de)(de)兩倍(bei)。前例(li)中電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)不(bu)(bu)(bu)(bu)平(ping)(ping)(ping)(ping)(ping)(ping)衡(heng)(heng)(heng)(heng)點數(shu)(shu)為(wei)5.2，繞(rao)組(zu)(zu)溫度增加(jia)的(de)(de)(de)百(bai)(bai)分(fen)數(shu)(shu)為(wei)54％。結(jie)果(guo)(guo)是(shi)一相(xiang)繞(rao)組(zu)(zu)過(guo)(guo)熱而其他兩個(ge)(ge)繞(rao)組(zu)(zu)溫度正(zheng)常。一份(fen)由U.L.(保(bao)險商實(shi)驗室，美國(guo)(guo))完成(cheng)的(de)(de)(de)調查顯示，43％的(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)力(li)公(gong)司(si)允(yun)許3％的(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)不(bu)(bu)(bu)(bu)平(ping)(ping)(ping)(ping)(ping)(ping)衡(heng)(heng)(heng)(heng)，另有(you)(you)30％的(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)力(li)公(gong)司(si)允(yun)許5％的(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)不(bu)(bu)(bu)(bu)平(ping)(ping)(ping)(ping)(ping)(ping)衡(heng)(heng)(heng)(heng)。

六、冷卻不足

功率較(jiao)大的壓縮機一般(ban)都是回氣冷卻型的。蒸(zheng)發(fa)溫度(du)越(yue)低，系統質量(liang)流往往越(yue)小。

當(dang)蒸發(fa)(fa)溫度(du)很(hen)低時（超過(guo)制(zhi)(zhi)(zhi)造商的(de)(de)(de)(de)規定），流量(liang)就不(bu)足以冷卻(que)(que)電機(ji)(ji)(ji)，電機(ji)(ji)(ji)就會(hui)在較(jiao)(jiao)高溫度(du)下運轉。空氣冷卻(que)(que)型壓(ya)縮(suo)機(ji)(ji)(ji)（一(yi)般不(bu)超過(guo)10HP）對回氣的(de)(de)(de)(de)依賴(lai)性(xing)小，但對壓(ya)縮(suo)機(ji)(ji)(ji)環境溫度(du)和(he)冷卻(que)(que)風(feng)量(liang)有(you)明(ming)確要求。制(zhi)(zhi)(zhi)冷劑(ji)大(da)量(liang)泄漏(lou)也會(hui)造成系統質量(liang)流減小，電機(ji)(ji)(ji)的(de)(de)(de)(de)冷卻(que)(que)也會(hui)受到影響(xiang)。一(yi)些(xie)無人看(kan)管的(de)(de)(de)(de)冷庫(ku)，往往要等到制(zhi)(zhi)(zhi)冷效果很(hen)差時才會(hui)發(fa)(fa)現(xian)制(zhi)(zhi)(zhi)冷劑(ji)大(da)量(liang)泄漏(lou)了(le)。電機(ji)(ji)(ji)過(guo)熱后會(hui)出現(xian)頻(pin)繁保(bao)護，有(you)些(xie)用戶不(bu)深(shen)入檢查原因(yin)，甚至將(jiang)熱保(bao)護器(qi)短路，那是非常(chang)(chang)糟(zao)糕的(de)(de)(de)(de)事(shi)情(qing)。過(guo)不(bu)了(le)多久，電機(ji)(ji)(ji)就會(hui)燒(shao)掉(diao)。壓(ya)縮(suo)機(ji)(ji)(ji)都有(you)安全運行工況(kuang)范圍。安全工況(kuang)主(zhu)要的(de)(de)(de)(de)考慮(lv)因(yin)素就是壓(ya)縮(suo)機(ji)(ji)(ji)和(he)電機(ji)(ji)(ji)的(de)(de)(de)(de)負荷與冷卻(que)(que)。由于不(bu)同溫區的(de)(de)(de)(de)壓(ya)縮(suo)機(ji)(ji)(ji)的(de)(de)(de)(de)價格不(bu)同，過(guo)去國內(nei)冷凍(dong)行業(ye)超范圍使用壓(ya)縮(suo)機(ji)(ji)(ji)是比較(jiao)(jiao)常(chang)(chang)見的(de)(de)(de)(de)。隨著專(zhuan)業(ye)知識的(de)(de)(de)(de)增長和(he)經(jing)濟條件(jian)的(de)(de)(de)(de)改(gai)善(shan)，情(qing)況(kuang)已明(ming)顯改(gai)善(shan)。