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（以下簡稱壓縮(suo)機(ji)）的故(gu)障可(ke)分為(wei)電機(ji)故(gu)障和機(ji)械故(gu)障（包括曲軸，連桿，活(huo)塞，閥片，缸蓋墊等）。

機(ji)械故障往往使(shi)電機(ji)超(chao)負荷運轉(zhuan)甚至(zhi)堵轉(zhuan)，是(shi)電機(ji)損壞的主要原因之一。

電(dian)(dian)機的(de)(de)損壞主要表現為定(ding)子(zi)繞組(zu)(zu)絕緣層(ceng)破壞（短路）和斷路等。定(ding)子(zi)繞組(zu)(zu)損壞后很(hen)難及(ji)時(shi)被(bei)發(fa)現，最(zui)終可能導致繞組(zu)(zu)燒(shao)毀(hui)。繞組(zu)(zu)燒(shao)毀(hui)后，掩蓋了一些導致燒(shao)毀(hui)的(de)(de)現象或直接原因，使(shi)得事(shi)后分析和原因調(diao)查比(bi)較困難。然而，電(dian)(dian)機的(de)(de)運轉離(li)不開正常的(de)(de)電(dian)(dian)源輸(shu)入，合(he)理的(de)(de)電(dian)(dian)機負荷，良好(hao)的(de)(de)散(san)熱和繞組(zu)(zu)漆包線絕緣層(ceng)的(de)(de)保護。

從這幾方面(mian)入(ru)手，不難(nan)發現繞組燒毀的原(yuan)因(yin)不外(wai)乎如下六種：

(1)異常負荷和堵轉(zhuan)；

(2)金屬屑引起的繞組短路；

(3)接觸器問題；

(4)電源缺相和電壓異常(chang)；

(5)冷卻(que)不足；

(6)用壓縮機抽真空。

實際上，多種因素共同促成(cheng)的電(dian)機損壞(huai)更為常(chang)見。

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二、異常負荷和堵轉

電(dian)機負(fu)荷(he)包(bao)括壓縮氣體所需負(fu)荷(he)以及克服機械摩擦所需負(fu)荷(he)。

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)過熱(re)，潤滑油(you)焦(jiao)化變質，以及缺油(you)等(deng)都(dou)會破壞正常(chang)潤滑，導致潤滑失(shi)效。回液(ye)稀釋潤滑油(you)，影響摩(mo)(mo)擦面正常(chang)油(you)膜(mo)的形成(cheng)，甚至沖刷掉原有油(you)膜(mo)，增加摩(mo)(mo)擦和磨(mo)損(sun)。壓(ya)縮(suo)機(ji)過熱(re)會引(yin)起(qi)使(shi)潤滑油(you)高溫(wen)變稀甚至焦(jiao)化，影響正常(chang)油(you)膜(mo)的形成(cheng)。系(xi)統回油(you)不好，壓(ya)縮(suo)機(ji)缺油(you)，自(zi)然無法維持正常(chang)潤滑。曲軸高速旋轉(zhuan)(zhuan)，連桿活塞(sai)等(deng)高速運動，沒有油(you)膜(mo)保護的摩(mo)(mo)擦面會迅(xun)速升溫(wen)，局(ju)部(bu)高溫(wen)使(shi)潤滑油(you)迅(xun)速蒸發或焦(jiao)化，使(shi)該部(bu)位(wei)潤滑更加困難，數秒鐘內可引(yin)起(qi)局(ju)部(bu)嚴重磨(mo)損(sun)。潤滑失(shi)效，局(ju)部(bu)磨(mo)損(sun)，使(shi)曲軸轉(zhuan)(zhuan)動需(xu)要更大力矩。

小功率(lv)壓(ya)(ya)縮(suo)機(ji)（如冰箱，家(jia)用空調壓(ya)(ya)縮(suo)機(ji)）由于電(dian)(dian)機(ji)扭(niu)矩小，潤(run)滑失效后(hou)常(chang)(chang)出現堵(du)轉(zhuan)(zhuan)（電(dian)(dian)機(ji)無(wu)法(fa)轉(zhuan)(zhuan)動(dong)(dong)）現象，并(bing)進入(ru)“堵(du)轉(zhuan)(zhuan)－熱(re)保護(hu)－堵(du)轉(zhuan)(zhuan)”死循環，電(dian)(dian)機(ji)燒毀(hui)只是時(shi)(shi)間問題。而(er)(er)大(da)功率(lv)半封閉壓(ya)(ya)縮(suo)機(ji)電(dian)(dian)機(ji)扭(niu)矩很(hen)大(da)，局部(bu)磨(mo)損(sun)不會(hui)(hui)(hui)引(yin)起(qi)(qi)堵(du)轉(zhuan)(zhuan)，電(dian)(dian)機(ji)功率(lv)會(hui)(hui)(hui)在(zai)一定(ding)范(fan)圍(wei)內隨負(fu)荷而(er)(er)增大(da)，從(cong)而(er)(er)引(yin)起(qi)(qi)更(geng)為嚴重的(de)(de)(de)磨(mo)損(sun)，甚(shen)至引(yin)起(qi)(qi)咬缸（活塞卡在(zai)氣(qi)缸內），連桿斷裂等嚴重損(sun)壞。堵(du)轉(zhuan)(zhuan)時(shi)(shi)的(de)(de)(de)電(dian)(dian)流（堵(du)轉(zhuan)(zhuan)電(dian)(dian)流）大(da)約是正常(chang)(chang)運行電(dian)(dian)流的(de)(de)(de)4－8倍。電(dian)(dian)機(ji)啟(qi)動(dong)(dong)瞬(shun)間，電(dian)(dian)流的(de)(de)(de)峰值(zhi)可接近或達(da)到堵(du)轉(zhuan)(zhuan)電(dian)(dian)流。由于電(dian)(dian)阻(zu)放熱(re)量與電(dian)(dian)流的(de)(de)(de)平方成正比(bi)，啟(qi)動(dong)(dong)和堵(du)轉(zhuan)(zhuan)時(shi)(shi)的(de)(de)(de)電(dian)(dian)流會(hui)(hui)(hui)使繞組(zu)(zu)迅速升溫。熱(re)保護(hu)可以在(zai)堵(du)轉(zhuan)(zhuan)時(shi)(shi)保護(hu)電(dian)(dian)極，但一般不會(hui)(hui)(hui)有很(hen)快的(de)(de)(de)響應，不能阻(zu)止頻(pin)繁啟(qi)動(dong)(dong)等引(yin)起(qi)(qi)的(de)(de)(de)繞組(zu)(zu)溫度(du)變(bian)化。頻(pin)繁啟(qi)動(dong)(dong)和異常(chang)(chang)負(fu)荷，使繞組(zu)(zu)經受高溫考驗，會(hui)(hui)(hui)降低漆包線(xian)的(de)(de)(de)絕緣(yuan)性能。此外，壓(ya)(ya)縮(suo)氣(qi)體所需(xu)負(fu)荷也會(hui)(hui)(hui)隨壓(ya)(ya)縮(suo)比(bi)增大(da)和壓(ya)(ya)差增大(da)而(er)(er)增大(da)。

因(yin)此將高溫壓縮機用于低溫，或將低溫壓縮機用于高溫，都(dou)會影(ying)響電(dian)機負荷和(he)散熱，是不合適的，會縮短(duan)(duan)電(dian)極使用壽命。繞組絕緣性能變差后，如果有其(qi)它因(yin)素(su)（如金(jin)屬屑構成(cheng)導電(dian)回路(lu)，酸(suan)性潤滑油(you)等）配合，很容易引起短(duan)(duan)路(lu)而損壞(huai)。

三、金屬屑引起的繞組短路

繞(rao)組(zu)中(zhong)夾雜(za)的金屬屑是短(duan)路和接地絕緣值低的罪魁禍首。

壓縮機運(yun)轉(zhuan)時的(de)(de)(de)正常振動(dong)(dong)(dong)，以(yi)及每(mei)次啟(qi)動(dong)(dong)(dong)時繞(rao)組受電(dian)磁力作用而扭動(dong)(dong)(dong)，都會(hui)促使夾雜于繞(rao)組間(jian)(jian)的(de)(de)(de)金屬屑(xie)與繞(rao)組漆(qi)(qi)包線之間(jian)(jian)的(de)(de)(de)相對運(yun)動(dong)(dong)(dong)和摩擦(ca)。棱(leng)角(jiao)銳利的(de)(de)(de)金屬屑(xie)會(hui)劃傷(shang)漆(qi)(qi)包線絕緣層(ceng)，引(yin)起短(duan)路。金屬屑(xie)的(de)(de)(de)來源包括施工時留下的(de)(de)(de)銅管屑(xie)，焊渣，壓(ya)(ya)(ya)縮(suo)(suo)(suo)(suo)(suo)機(ji)內部磨損(sun)(sun)和零部件損(sun)(sun)壞(huai)（比(bi)如閥片破碎）時掉下的(de)(de)(de)金屬屑(xie)等。對于全封閉壓(ya)(ya)(ya)縮(suo)(suo)(suo)(suo)(suo)機(ji)（包括全封閉渦(wo)旋壓(ya)(ya)(ya)縮(suo)(suo)(suo)(suo)(suo)機(ji)），這些(xie)金屬屑(xie)或碎粒(li)會(hui)落在(zai)(zai)繞(rao)組上。對于半(ban)封閉壓(ya)(ya)(ya)縮(suo)(suo)(suo)(suo)(suo)機(ji)，有些(xie)顆粒(li)會(hui)隨氣(qi)(qi)體和潤滑(hua)油在(zai)(zai)系統中流動(dong)(dong)(dong)，最后(hou)(hou)(hou)由于磁性聚集在(zai)(zai)繞(rao)組中；而有些(xie)金屬屑(xie)（比(bi)如軸(zhou)承磨損(sun)(sun)以(yi)及電(dian)機(ji)轉(zhuan)子與定子磨損(sun)(sun)（掃膛）時產生的(de)(de)(de)）會(hui)直(zhi)接(jie)落在(zai)(zai)繞(rao)組上。繞(rao)組中聚集了金屬屑(xie)后(hou)(hou)(hou)，發生短(duan)路只是一(yi)個時間(jian)(jian)問題。需(xu)要(yao)特別提(ti)請注意的(de)(de)(de)是雙級(ji)(ji)壓(ya)(ya)(ya)縮(suo)(suo)(suo)(suo)(suo)機(ji)。在(zai)(zai)雙級(ji)(ji)壓(ya)(ya)(ya)縮(suo)(suo)(suo)(suo)(suo)機(ji)中，回氣(qi)(qi)以(yi)及正常的(de)(de)(de)回油直(zhi)接(jie)進(jin)(jin)入第(di)一(yi)級(ji)(ji)（低壓(ya)(ya)(ya)級(ji)(ji)）氣(qi)(qi)缸(gang)(gang)(gang)，壓(ya)(ya)(ya)縮(suo)(suo)(suo)(suo)(suo)后(hou)(hou)(hou)經中壓(ya)(ya)(ya)管進(jin)(jin)入電(dian)機(ji)腔冷卻繞(rao)組，然后(hou)(hou)(hou)和普通單(dan)級(ji)(ji)壓(ya)(ya)(ya)縮(suo)(suo)(suo)(suo)(suo)機(ji)一(yi)樣，進(jin)(jin)入第(di)二級(ji)(ji)（高壓(ya)(ya)(ya)級(ji)(ji)氣(qi)(qi)缸(gang)(gang)(gang)）。回氣(qi)(qi)中帶有潤滑(hua)油，已經使壓(ya)(ya)(ya)縮(suo)(suo)(suo)(suo)(suo)過程如履薄冰，如果(guo)再有回液，第(di)一(yi)級(ji)(ji)氣(qi)(qi)缸(gang)(gang)(gang)的(de)(de)(de)閥片很容易(yi)被打(da)碎。碎閥片經中壓(ya)(ya)(ya)管后(hou)(hou)(hou)可(ke)進(jin)(jin)入繞(rao)組。因(yin)此，雙級(ji)(ji)壓(ya)(ya)(ya)縮(suo)(suo)(suo)(suo)(suo)機(ji)比(bi)單(dan)級(ji)(ji)壓(ya)(ya)(ya)縮(suo)(suo)(suo)(suo)(suo)機(ji)更(geng)容易(yi)出(chu)現金屬屑(xie)引(yin)起的(de)(de)(de)電(dian)機(ji)短(duan)路。

不幸的(de)(de)事情(qing)往往湊到一塊(kuai)，出問題的(de)(de)壓縮機在開機分析時聞道的(de)(de)常常是(shi)潤滑(hua)(hua)油(you)(you)的(de)(de)焦糊味。金屬(shu)面嚴重磨損時溫度(du)是(shi)很高的(de)(de)，而潤滑(hua)(hua)油(you)(you)在175?C以上時開始焦化。系統中(zhong)如(ru)果有較多水分（真(zhen)空(kong)抽得不理想，潤滑(hua)(hua)油(you)(you)和制冷劑含(han)水量大，負壓回氣管破裂后空(kong)氣進入等），潤滑(hua)(hua)油(you)(you)就可能(neng)出現(xian)酸性(xing)。酸性(xing)潤滑(hua)(hua)油(you)(you)會腐蝕銅(tong)管和繞組絕(jue)緣層(ceng)，一方面，它會引起(qi)鍍銅(tong)現(xian)象；另一方面，這種(zhong)含(han)有銅(tong)原子的(de)(de)酸性(xing)潤滑(hua)(hua)油(you)(you)的(de)(de)絕(jue)緣性(xing)能(neng)很差，為繞組短路提供了條(tiao)件(jian)。

四、接觸器問題

接觸器是(shi)電機控制回路中重(zhong)要部件(jian)之(zhi)一，選型不合理可以(yi)毀壞最好的(de)壓縮機。

按負(fu)載正確選擇接觸(chu)器是極其重要(yao)的(de)(de)(de)。接觸(chu)器必(bi)(bi)須(xu)能滿足苛刻的(de)(de)(de)條件，如(ru)(ru)快速循環(huan)，持續超(chao)載和低電(dian)(dian)(dian)壓。它們(men)必(bi)(bi)須(xu)有足夠大的(de)(de)(de)面積以散發負(fu)載電(dian)(dian)(dian)流(liu)(liu)所產生的(de)(de)(de)熱量，觸(chu)點材(cai)料的(de)(de)(de)選擇必(bi)(bi)須(xu)在啟動或堵轉等(deng)大電(dian)(dian)(dian)流(liu)(liu)情(qing)況下(xia)能防(fang)止焊合(he)。為了安全可靠，壓縮機接觸(chu)器要(yao)同時斷(duan)開三相電(dian)(dian)(dian)路。谷(gu)輪公司不推薦斷(duan)開二(er)相電(dian)(dian)(dian)路的(de)(de)(de)方(fang)法。在美國，谷(gu)輪公司認可的(de)(de)(de)接觸(chu)器必(bi)(bi)須(xu)滿足如(ru)(ru)下(xia)四項(xiang)：

接(jie)觸器(qi)必須滿足ARI標(biao)準(zhun)(zhun)780-78“專用接(jie)觸器(qi)標(biao)準(zhun)(zhun)”規定的工作(zuo)和(he)測試(shi)準(zhun)(zhun)則。

制造商(shang)必須保證(zheng)接觸器在室溫(wen)下，在最低銘牌電壓的80％時能閉合。

當使(shi)用單個接觸器時(shi)，接觸器額定電流(liu)必(bi)須(xu)大于(yu)電機(ji)銘牌電流(liu)額定值(RLA).同時(shi)，接觸器必(bi)須(xu)能承受(shou)電機(ji)堵轉(zhuan)電流(liu)。如果接觸器下(xia)游還有其它負載，比如電機(ji)風扇等，也必(bi)須(xu)考慮。

當使用兩個接(jie)觸器時，每個接(jie)觸器的分繞組(zu)堵(du)轉(zhuan)額定值必須等于或大于壓縮機半繞組(zu)堵(du)轉(zhuan)額定值。

接(jie)觸(chu)器的額定電流不能低于壓縮機銘牌上的額定電流。

規格小或質(zhi)量低劣的接(jie)(jie)觸(chu)器無法經受壓縮(suo)機(ji)(ji)啟(qi)(qi)動(dong)(dong)(dong)，堵轉和低電(dian)壓時的大電(dian)流(liu)沖擊(ji)，容易(yi)(yi)(yi)出現(xian)單(dan)相或多(duo)相觸(chu)點抖(dou)動(dong)(dong)(dong),焊接(jie)(jie)甚至脫落(luo)的現(xian)象，引(yin)起電(dian)機(ji)(ji)損(sun)壞。觸(chu)點抖(dou)動(dong)(dong)(dong)的接(jie)(jie)觸(chu)器頻(pin)繁(fan)地啟(qi)(qi)停電(dian)機(ji)(ji)。電(dian)機(ji)(ji)頻(pin)繁(fan)啟(qi)(qi)動(dong)(dong)(dong)，巨大的啟(qi)(qi)動(dong)(dong)(dong)電(dian)流(liu)和發熱,會加劇(ju)繞組(zu)絕(jue)緣層的老化。每次啟(qi)(qi)動(dong)(dong)(dong)時，磁性力矩(ju)使電(dian)機(ji)(ji)繞組(zu)有微小的移(yi)動(dong)(dong)(dong)和相互摩擦。如果有其它因素配合（如金(jin)屬屑，絕(jue)緣性差的潤滑油等），很容易(yi)(yi)(yi)引(yin)起繞組(zu)間短路。熱保護系統并未設計成能防止這種毀壞。此外，抖(dou)動(dong)(dong)(dong)的接(jie)(jie)觸(chu)器線圈容易(yi)(yi)(yi)失效。如果有接(jie)(jie)觸(chu)線圈損(sun)壞，容易(yi)(yi)(yi)出現(xian)單(dan)相狀態。

如(ru)果(guo)接觸(chu)(chu)(chu)(chu)器(qi)(qi)選型偏小，觸(chu)(chu)(chu)(chu)頭(tou)(tou)不(bu)能承受電弧和(he)由于頻繁(fan)開停循環或(huo)不(bu)穩(wen)定控制(zhi)(zhi)回路電壓產(chan)生的(de)(de)高(gao)溫，可能焊(han)合或(huo)從觸(chu)(chu)(chu)(chu)頭(tou)(tou)架(jia)中(zhong)脫(tuo)落。焊(han)合的(de)(de)觸(chu)(chu)(chu)(chu)頭(tou)(tou)將(jiang)產(chan)生永久性單相狀(zhuang)態，使過(guo)載(zai)保(bao)護器(qi)(qi)持續地循環接通(tong)和(he)斷(duan)開，需要特(te)別強調的(de)(de)是，接觸(chu)(chu)(chu)(chu)器(qi)(qi)觸(chu)(chu)(chu)(chu)點焊(han)合后，依賴接觸(chu)(chu)(chu)(chu)器(qi)(qi)斷(duan)開壓縮(suo)機(ji)電源回路的(de)(de)所有控制(zhi)(zhi)（比如(ru)高(gao)低壓控制(zhi)(zhi)，油壓控制(zhi)(zhi)，融霜(shuang)控制(zhi)(zhi)等(deng)）將(jiang)全部(bu)失效，壓縮(suo)機(ji)處于無保(bao)護狀(zhuang)態。

因此，當電(dian)機燒(shao)毀(hui)后，檢查接觸器是(shi)必不可少的(de)(de)工(gong)序。接觸器是(shi)導(dao)致電(dian)機損壞(huai)的(de)(de)一個常常被人遺(yi)忘(wang)的(de)(de)重要原因。

五、電源缺相和電壓異常

電壓不(bu)正常和缺相(xiang)可(ke)以(yi)輕而易舉地毀掉任(ren)何電機。

電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)變化范圍不(bu)(bu)(bu)(bu)能(neng)超過(guo)額(e)定(ding)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)的(de)(de)(de)±10%。三(san)相(xiang)(xiang)(xiang)間的(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(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)衡不(bu)(bu)(bu)(bu)能(neng)超過(guo)5％。大(da)(da)功率(lv)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)必(bi)須獨立供(gong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)，以防(fang)同(tong)線(xian)其(qi)他大(da)(da)功率(lv)設(she)(she)備啟動和運轉(zhuan)時(shi)造(zao)成低電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)。電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)線(xian)必(bi)須能(neng)夠(gou)承載(zai)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)的(de)(de)(de)額(e)定(ding)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)。如果發(fa)(fa)生缺(que)相(xiang)(xiang)(xiang)時(shi)壓(ya)(ya)(ya)(ya)(ya)縮(suo)機(ji)正在(zai)(zai)運轉(zhuan)，它將繼續運行但會(hui)(hui)有(you)大(da)(da)的(de)(de)(de)負載(zai)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)。電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)繞(rao)組(zu)(zu)會(hui)(hui)很快過(guo)熱，正常(chang)(chang)情況下壓(ya)(ya)(ya)(ya)(ya)縮(suo)機(ji)會(hui)(hui)被熱保護(hu)。當電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)繞(rao)組(zu)(zu)冷卻至設(she)(she)定(ding)溫(wen)度(du)，接觸器(qi)會(hui)(hui)閉合，但壓(ya)(ya)(ya)(ya)(ya)縮(suo)機(ji)啟動不(bu)(bu)(bu)(bu)起(qi)來，出(chu)現(xian)堵(du)轉(zhuan)，并進入“堵(du)轉(zhuan)－熱保護(hu)－堵(du)轉(zhuan)”死循(xun)環(huan)。現(xian)代電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)繞(rao)組(zu)(zu)的(de)(de)(de)差(cha)別(bie)(bie)非(fei)常(chang)(chang)小，電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)三(san)相(xiang)(xiang)(xiang)平(ping)(ping)(ping)(ping)(ping)衡時(shi)相(xiang)(xiang)(xiang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)的(de)(de)(de)差(cha)別(bie)(bie)可(ke)(ke)以忽(hu)略。理想狀(zhuang)態下，相(xiang)(xiang)(xiang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)始(shi)終相(xiang)(xiang)(xiang)等(deng)，只要在(zai)(zai)任一(yi)(yi)相(xiang)(xiang)(xiang)上(shang)接一(yi)(yi)個保護(hu)器(qi)就可(ke)(ke)以防(fang)止過(guo)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)造(zao)成的(de)(de)(de)損壞。實際上(shang)很難保證相(xiang)(xiang)(xiang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)的(de)(de)(de)平(ping)(ping)(ping)(ping)(ping)衡。電(dian)(dian)(dian)(dian)(dian)(dian)(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)衡百(bai)(bai)分(fen)數(shu)計(ji)(ji)算(suan)(suan)方法(fa)為(wei)(wei)(wei)，相(xiang)(xiang)(xiang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)與三(san)相(xiang)(xiang)(xiang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)平(ping)(ping)(ping)(ping)(ping)均值(zhi)的(de)(de)(de)最大(da)(da)偏(pian)差(cha)值(zhi)與三(san)相(xiang)(xiang)(xiang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)平(ping)(ping)(ping)(ping)(ping)均值(zhi)比(bi)值(zhi)。例(li)如，標稱380V三(san)相(xiang)(xiang)(xiang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)，在(zai)(zai)壓(ya)(ya)(ya)(ya)(ya)縮(suo)機(ji)接線(xian)端測(ce)量的(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)分(fen)別(bie)(bie)為(wei)(wei)(wei)380V、366V、400V。可(ke)(ke)以計(ji)(ji)算(suan)(suan)出(chu)三(san)相(xiang)(xiang)(xiang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)平(ping)(ping)(ping)(ping)(ping)均值(zhi)382V，最大(da)(da)偏(pian)差(cha)為(wei)(wei)(wei)20V,所以電(dian)(dian)(dian)(dian)(dian)(dian)(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)衡百(bai)(bai)分(fen)數(shu)為(wei)(wei)(wei)5.2％。作為(wei)(wei)(wei)電(dian)(dian)(dian)(dian)(dian)(dian)(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)衡的(de)(de)(de)結(jie)果，在(zai)(zai)正常(chang)(chang)運行使負載(zai)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)的(de)(de)(de)不(bu)(bu)(bu)(bu)平(ping)(ping)(ping)(ping)(ping)衡是電(dian)(dian)(dian)(dian)(dian)(dian)(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)衡百(bai)(bai)分(fen)點(dian)(dian)數(shu)的(de)(de)(de)4－10倍。前例(li)中，5.2％不(bu)(bu)(bu)(bu)平(ping)(ping)(ping)(ping)(ping)衡電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)可(ke)(ke)能(neng)引起(qi)50％的(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)不(bu)(bu)(bu)(bu)平(ping)(ping)(ping)(ping)(ping)衡。美國(guo)國(guo)家電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)器(qi)制(zhi)造(zao)商協會(hui)(hui)(NEMA)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)動機(ji)和發(fa)(fa)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)標準出(chu)版(ban)物指(zhi)出(chu)，由不(bu)(bu)(bu)(bu)平(ping)(ping)(ping)(ping)(ping)衡電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)造(zao)成的(de)(de)(de)相(xiang)(xiang)(xiang)繞(rao)組(zu)(zu)溫(wen)升(sheng)百(bai)(bai)分(fen)比(bi)大(da)(da)約是電(dian)(dian)(dian)(dian)(dian)(dian)(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)衡百(bai)(bai)分(fen)點(dian)(dian)數(shu)平(ping)(ping)(ping)(ping)(ping)方的(de)(de)(de)兩(liang)倍。前例(li)中電(dian)(dian)(dian)(dian)(dian)(dian)(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)衡點(dian)(dian)數(shu)為(wei)(wei)(wei)5.2，繞(rao)組(zu)(zu)溫(wen)度(du)增加的(de)(de)(de)百(bai)(bai)分(fen)數(shu)為(wei)(wei)(wei)54％。結(jie)果是一(yi)(yi)相(xiang)(xiang)(xiang)繞(rao)組(zu)(zu)過(guo)熱而其(qi)他兩(liang)個繞(rao)組(zu)(zu)溫(wen)度(du)正常(chang)(chang)。一(yi)(yi)份(fen)由U.L.(保險商實驗室，美國(guo))完成的(de)(de)(de)調(diao)查顯示，43％的(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)力公(gong)司(si)允許3％的(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(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)衡，另有(you)30％的(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)力公(gong)司(si)允許5％的(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(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)衡。

六、冷卻不足

功(gong)率較(jiao)大的(de)壓縮(suo)機一般都(dou)是回氣冷卻型的(de)。蒸(zheng)發溫度越(yue)低，系統質量流(liu)往(wang)往(wang)越(yue)小(xiao)。

當蒸(zheng)發溫(wen)(wen)度很低時（超過制(zhi)造(zao)商(shang)的(de)規(gui)定），流量(liang)就(jiu)不足以(yi)冷卻電(dian)機(ji)(ji)，電(dian)機(ji)(ji)就(jiu)會(hui)在(zai)較高溫(wen)(wen)度下運轉。空氣冷卻型壓縮機(ji)(ji)（一般不超過10HP）對(dui)(dui)回(hui)氣的(de)依賴性(xing)小(xiao)，但對(dui)(dui)壓縮機(ji)(ji)環境溫(wen)(wen)度和(he)冷卻風量(liang)有明確要(yao)(yao)求。制(zhi)冷劑大(da)量(liang)泄漏(lou)也(ye)會(hui)造(zao)成系統質量(liang)流減小(xiao)，電(dian)機(ji)(ji)的(de)冷卻也(ye)會(hui)受(shou)到影響。一些無(wu)人看管的(de)冷庫(ku)，往(wang)往(wang)要(yao)(yao)等到制(zhi)冷效果(guo)很差時才會(hui)發現制(zhi)冷劑大(da)量(liang)泄漏(lou)了(le)。電(dian)機(ji)(ji)過熱后會(hui)出現頻繁(fan)保護，有些用(yong)戶不深入(ru)檢(jian)查原因(yin)，甚至(zhi)將熱保護器(qi)短路，那是非常糟糕(gao)的(de)事情。過不了(le)多久，電(dian)機(ji)(ji)就(jiu)會(hui)燒掉。壓縮機(ji)(ji)都有安(an)全(quan)運行工(gong)況范圍(wei)。安(an)全(quan)工(gong)況主要(yao)(yao)的(de)考慮因(yin)素就(jiu)是壓縮機(ji)(ji)和(he)電(dian)機(ji)(ji)的(de)負荷與冷卻。由(you)于不同(tong)溫(wen)(wen)區的(de)壓縮機(ji)(ji)的(de)價格不同(tong)，過去國內(nei)冷凍行業(ye)超范圍(wei)使用(yong)壓縮機(ji)(ji)是比較常見的(de)。隨著專業(ye)知識的(de)增長和(he)經濟(ji)條件的(de)改(gai)善，情況已明顯改(gai)善。