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(yi)下簡稱壓縮機(ji)(ji)）的(de)故障可分為電機(ji)(ji)故障和機(ji)(ji)械故障（包括曲(qu)軸，連桿，活塞，閥片，缸(gang)蓋墊等）。

機(ji)械故障(zhang)往往使電機(ji)超負荷運轉甚至堵(du)轉，是電機(ji)損壞的主要原因之一(yi)。

電機的損壞主要(yao)表現為定(ding)子(zi)繞(rao)組(zu)(zu)絕緣層破壞（短路）和斷路等。定(ding)子(zi)繞(rao)組(zu)(zu)損壞后很難及時(shi)被發現，最終可(ke)能導致繞(rao)組(zu)(zu)燒(shao)毀。繞(rao)組(zu)(zu)燒(shao)毀后，掩蓋了一些導致燒(shao)毀的現象(xiang)或直接原因，使得事(shi)后分析(xi)和原因調查比較(jiao)困難。然而，電機的運轉離(li)不開正常的電源輸入，合理的電機負荷，良好(hao)的散熱(re)和繞(rao)組(zu)(zu)漆包線絕緣層的保(bao)護(hu)。

從這幾方面入手，不難(nan)發現(xian)繞組(zu)燒(shao)毀的原因不外(wai)乎如下(xia)六種：

(1)異(yi)常負荷和堵轉；

(2)金屬屑引(yin)起的繞組短(duan)路；

(3)接觸(chu)器(qi)問題；

(4)電源缺相和電壓(ya)異常；

(5)冷卻(que)不足；

(6)用壓縮機抽(chou)真空。

實際上，多種因素共同(tong)促成的(de)電機損(sun)壞更為常見。

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二、異常負荷和堵轉

電機負(fu)荷包括壓(ya)縮氣體所需(xu)負(fu)荷以(yi)及克服機械摩擦(ca)所需(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(run)滑(hua)(hua)(hua)油(you)過熱(re)，潤(run)滑(hua)(hua)(hua)油(you)焦(jiao)化(hua)(hua)變質，以及缺油(you)等都(dou)會破壞正常(chang)潤(run)滑(hua)(hua)(hua)，導致潤(run)滑(hua)(hua)(hua)失(shi)(shi)效(xiao)。回液稀釋潤(run)滑(hua)(hua)(hua)油(you)，影響摩擦面正常(chang)油(you)膜的形成(cheng)，甚至(zhi)沖刷掉(diao)原有油(you)膜，增(zeng)加摩擦和磨損。壓縮(suo)機過熱(re)會引起(qi)使(shi)潤(run)滑(hua)(hua)(hua)油(you)高(gao)溫變稀甚至(zhi)焦(jiao)化(hua)(hua)，影響正常(chang)油(you)膜的形成(cheng)。系統回油(you)不好，壓縮(suo)機缺油(you)，自然無法維持正常(chang)潤(run)滑(hua)(hua)(hua)。曲軸高(gao)速旋(xuan)轉(zhuan)，連桿活塞等高(gao)速運(yun)動，沒有油(you)膜保(bao)護的摩擦面會迅速升溫，局(ju)部高(gao)溫使(shi)潤(run)滑(hua)(hua)(hua)油(you)迅速蒸(zheng)發或焦(jiao)化(hua)(hua)，使(shi)該部位(wei)潤(run)滑(hua)(hua)(hua)更加困難，數秒鐘內可引起(qi)局(ju)部嚴(yan)重磨損。潤(run)滑(hua)(hua)(hua)失(shi)(shi)效(xiao)，局(ju)部磨損，使(shi)曲軸轉(zhuan)動需要更大力(li)矩。

小功(gong)率(lv)壓(ya)(ya)縮(suo)機(ji)(ji)（如冰箱(xiang)，家用空調壓(ya)(ya)縮(suo)機(ji)(ji)）由(you)于電(dian)(dian)(dian)(dian)機(ji)(ji)扭矩小，潤滑(hua)失效后常出現(xian)堵(du)轉(zhuan)(zhuan)(zhuan)(zhuan)（電(dian)(dian)(dian)(dian)機(ji)(ji)無法轉(zhuan)(zhuan)(zhuan)(zhuan)動）現(xian)象，并進入“堵(du)轉(zhuan)(zhuan)(zhuan)(zhuan)－熱保護－堵(du)轉(zhuan)(zhuan)(zhuan)(zhuan)”死循環，電(dian)(dian)(dian)(dian)機(ji)(ji)燒毀只是時間問題(ti)。而(er)大(da)(da)(da)功(gong)率(lv)半封閉(bi)壓(ya)(ya)縮(suo)機(ji)(ji)電(dian)(dian)(dian)(dian)機(ji)(ji)扭矩很大(da)(da)(da)，局部磨損(sun)不會(hui)引(yin)起(qi)堵(du)轉(zhuan)(zhuan)(zhuan)(zhuan)，電(dian)(dian)(dian)(dian)機(ji)(ji)功(gong)率(lv)會(hui)在(zai)一(yi)定范圍內隨負(fu)荷而(er)增大(da)(da)(da)，從而(er)引(yin)起(qi)更為嚴(yan)重的(de)(de)磨損(sun)，甚至引(yin)起(qi)咬缸（活塞卡在(zai)氣缸內），連(lian)桿斷裂等嚴(yan)重損(sun)壞(huai)。堵(du)轉(zhuan)(zhuan)(zhuan)(zhuan)時的(de)(de)電(dian)(dian)(dian)(dian)流(liu)（堵(du)轉(zhuan)(zhuan)(zhuan)(zhuan)電(dian)(dian)(dian)(dian)流(liu)）大(da)(da)(da)約是正常運行(xing)電(dian)(dian)(dian)(dian)流(liu)的(de)(de)4－8倍。電(dian)(dian)(dian)(dian)機(ji)(ji)啟動瞬間，電(dian)(dian)(dian)(dian)流(liu)的(de)(de)峰值可接近或(huo)達到(dao)堵(du)轉(zhuan)(zhuan)(zhuan)(zhuan)電(dian)(dian)(dian)(dian)流(liu)。由(you)于電(dian)(dian)(dian)(dian)阻放熱量與電(dian)(dian)(dian)(dian)流(liu)的(de)(de)平方成正比，啟動和堵(du)轉(zhuan)(zhuan)(zhuan)(zhuan)時的(de)(de)電(dian)(dian)(dian)(dian)流(liu)會(hui)使繞(rao)組迅速(su)升溫。熱保護可以在(zai)堵(du)轉(zhuan)(zhuan)(zhuan)(zhuan)時保護電(dian)(dian)(dian)(dian)極，但一(yi)般不會(hui)有很快的(de)(de)響應(ying)，不能阻止(zhi)頻繁啟動等引(yin)起(qi)的(de)(de)繞(rao)組溫度變化。頻繁啟動和異常負(fu)荷，使繞(rao)組經受(shou)高溫考(kao)驗，會(hui)降低(di)漆包(bao)線的(de)(de)絕緣性能。此外，壓(ya)(ya)縮(suo)氣體(ti)所需負(fu)荷也會(hui)隨壓(ya)(ya)縮(suo)比增大(da)(da)(da)和壓(ya)(ya)差增大(da)(da)(da)而(er)增大(da)(da)(da)。

因(yin)此將(jiang)高溫(wen)壓縮機用于(yu)低溫(wen)，或(huo)將(jiang)低溫(wen)壓縮機用于(yu)高溫(wen)，都會影響電機負荷和散熱，是不合(he)(he)適的，會縮短電極使用壽(shou)命。繞組絕緣性能變差后，如果有其(qi)它因(yin)素(su)（如金屬屑構成(cheng)導電回路(lu)，酸性潤滑油等）配合(he)(he)，很容易引起短路(lu)而損(sun)壞。

三、金屬屑引起的繞組短路

繞(rao)組中(zhong)夾雜(za)的金(jin)屬屑是短路和接地絕緣值低的罪魁(kui)禍首(shou)。

壓縮機運轉時的(de)(de)正(zheng)常振動，以(yi)及每次啟動時繞(rao)組(zu)(zu)受電(dian)磁力作用而(er)扭動，都會(hui)(hui)(hui)促使(shi)(shi)夾(jia)雜(za)于(yu)繞(rao)組(zu)(zu)間的(de)(de)金(jin)(jin)(jin)屬(shu)(shu)(shu)屑(xie)(xie)與(yu)繞(rao)組(zu)(zu)漆包(bao)(bao)線之間的(de)(de)相對運動和(he)摩擦(ca)。棱(leng)角銳(rui)利的(de)(de)金(jin)(jin)(jin)屬(shu)(shu)(shu)屑(xie)(xie)會(hui)(hui)(hui)劃傷漆包(bao)(bao)線絕緣層(ceng)，引起短路。金(jin)(jin)(jin)屬(shu)(shu)(shu)屑(xie)(xie)的(de)(de)來源包(bao)(bao)括施工時留下(xia)的(de)(de)銅管屑(xie)(xie)，焊渣，壓(ya)(ya)縮(suo)(suo)(suo)機(ji)(ji)內部磨(mo)損和(he)零部件損壞(huai)（比(bi)如閥(fa)片破(po)碎(sui)(sui)）時掉下(xia)的(de)(de)金(jin)(jin)(jin)屬(shu)(shu)(shu)屑(xie)(xie)等。對于(yu)全(quan)封(feng)閉壓(ya)(ya)縮(suo)(suo)(suo)機(ji)(ji)（包(bao)(bao)括全(quan)封(feng)閉渦(wo)旋壓(ya)(ya)縮(suo)(suo)(suo)機(ji)(ji)），這些(xie)金(jin)(jin)(jin)屬(shu)(shu)(shu)屑(xie)(xie)或碎(sui)(sui)粒會(hui)(hui)(hui)落(luo)在(zai)繞(rao)組(zu)(zu)上(shang)(shang)。對于(yu)半封(feng)閉壓(ya)(ya)縮(suo)(suo)(suo)機(ji)(ji)，有(you)(you)些(xie)顆粒會(hui)(hui)(hui)隨(sui)氣(qi)體和(he)潤滑油(you)(you)在(zai)系(xi)統(tong)中(zhong)流動，最(zui)后(hou)(hou)由于(yu)磁性聚(ju)集(ji)在(zai)繞(rao)組(zu)(zu)中(zhong)；而(er)有(you)(you)些(xie)金(jin)(jin)(jin)屬(shu)(shu)(shu)屑(xie)(xie)（比(bi)如軸承磨(mo)損以(yi)及電(dian)機(ji)(ji)轉子與(yu)定(ding)子磨(mo)損（掃膛）時產生(sheng)的(de)(de)）會(hui)(hui)(hui)直(zhi)接(jie)落(luo)在(zai)繞(rao)組(zu)(zu)上(shang)(shang)。繞(rao)組(zu)(zu)中(zhong)聚(ju)集(ji)了金(jin)(jin)(jin)屬(shu)(shu)(shu)屑(xie)(xie)后(hou)(hou)，發生(sheng)短路只是一(yi)(yi)個時間問題。需要特別(bie)提請注意的(de)(de)是雙級(ji)壓(ya)(ya)縮(suo)(suo)(suo)機(ji)(ji)。在(zai)雙級(ji)壓(ya)(ya)縮(suo)(suo)(suo)機(ji)(ji)中(zhong)，回氣(qi)以(yi)及正(zheng)常的(de)(de)回油(you)(you)直(zhi)接(jie)進(jin)入(ru)第(di)(di)一(yi)(yi)級(ji)（低壓(ya)(ya)級(ji)）氣(qi)缸(gang)，壓(ya)(ya)縮(suo)(suo)(suo)后(hou)(hou)經中(zhong)壓(ya)(ya)管進(jin)入(ru)電(dian)機(ji)(ji)腔冷卻(que)繞(rao)組(zu)(zu)，然后(hou)(hou)和(he)普通單級(ji)壓(ya)(ya)縮(suo)(suo)(suo)機(ji)(ji)一(yi)(yi)樣，進(jin)入(ru)第(di)(di)二(er)級(ji)（高(gao)壓(ya)(ya)級(ji)氣(qi)缸(gang)）。回氣(qi)中(zhong)帶有(you)(you)潤滑油(you)(you)，已(yi)經使(shi)(shi)壓(ya)(ya)縮(suo)(suo)(suo)過程如履薄(bo)冰(bing)，如果再有(you)(you)回液，第(di)(di)一(yi)(yi)級(ji)氣(qi)缸(gang)的(de)(de)閥(fa)片很容易被打碎(sui)(sui)。碎(sui)(sui)閥(fa)片經中(zhong)壓(ya)(ya)管后(hou)(hou)可進(jin)入(ru)繞(rao)組(zu)(zu)。因此，雙級(ji)壓(ya)(ya)縮(suo)(suo)(suo)機(ji)(ji)比(bi)單級(ji)壓(ya)(ya)縮(suo)(suo)(suo)機(ji)(ji)更(geng)容易出(chu)現金(jin)(jin)(jin)屬(shu)(shu)(shu)屑(xie)(xie)引起的(de)(de)電(dian)機(ji)(ji)短路。

不(bu)幸的(de)事(shi)情往往湊到一塊(kuai)，出(chu)問題(ti)的(de)壓(ya)縮機(ji)在開機(ji)分(fen)析時聞道(dao)的(de)常常是(shi)潤(run)(run)滑(hua)油(you)(you)的(de)焦糊味(wei)。金屬面嚴重(zhong)磨損時溫度是(shi)很高的(de)，而潤(run)(run)滑(hua)油(you)(you)在175?C以上時開始(shi)焦化。系統中如果(guo)有(you)較多水(shui)分(fen)（真(zhen)空抽得(de)不(bu)理想，潤(run)(run)滑(hua)油(you)(you)和制冷(leng)劑含水(shui)量大(da)，負壓(ya)回氣管(guan)破裂后空氣進入等），潤(run)(run)滑(hua)油(you)(you)就可能出(chu)現(xian)酸性。酸性潤(run)(run)滑(hua)油(you)(you)會腐蝕銅管(guan)和繞組絕緣層，一方面，它(ta)會引起鍍銅現(xian)象；另(ling)一方面，這種含有(you)銅原(yuan)子的(de)酸性潤(run)(run)滑(hua)油(you)(you)的(de)絕緣性能很差(cha)，為繞組短路提供了條件。

四、接觸器問題

接觸(chu)器是電機控制回路中重要部件之一，選(xuan)型(xing)不合(he)理可以毀壞最好的壓縮機。

按負載(zai)正確選擇接(jie)(jie)觸(chu)器(qi)是極其重要的(de)(de)(de)。接(jie)(jie)觸(chu)器(qi)必須能(neng)滿(man)足苛(ke)刻的(de)(de)(de)條件，如快速循環，持續(xu)超載(zai)和低電壓(ya)(ya)。它們必須有足夠大的(de)(de)(de)面積以散發負載(zai)電流(liu)(liu)所產生的(de)(de)(de)熱量(liang)，觸(chu)點材料(liao)的(de)(de)(de)選擇必須在啟(qi)動或堵轉等大電流(liu)(liu)情(qing)況(kuang)下能(neng)防止焊合。為了安全可靠，壓(ya)(ya)縮機(ji)接(jie)(jie)觸(chu)器(qi)要同(tong)時斷開(kai)三相電路(lu)(lu)。谷輪公司不推薦(jian)斷開(kai)二(er)相電路(lu)(lu)的(de)(de)(de)方法。在美國，谷輪公司認可的(de)(de)(de)接(jie)(jie)觸(chu)器(qi)必須滿(man)足如下四項：

接觸器(qi)必(bi)須滿足ARI標(biao)準780-78“專(zhuan)用接觸器(qi)標(biao)準”規定的工作(zuo)和測試準則。

制造(zao)商必須保證接觸器在室(shi)溫下，在最低銘牌電壓的80％時能閉合。

當使(shi)用單個接(jie)(jie)觸器時(shi)(shi)，接(jie)(jie)觸器額定(ding)電流(liu)(liu)必(bi)須大于電機銘牌電流(liu)(liu)額定(ding)值(zhi)(RLA).同(tong)時(shi)(shi)，接(jie)(jie)觸器必(bi)須能承受(shou)電機堵轉電流(liu)(liu)。如果接(jie)(jie)觸器下游還有其它(ta)負載，比如電機風扇等(deng)，也必(bi)須考(kao)慮。

當使用兩個接觸(chu)器時，每個接觸(chu)器的分(fen)繞(rao)組(zu)堵(du)轉額定值必須(xu)等于或大于壓縮機(ji)半繞(rao)組(zu)堵(du)轉額定值。

接(jie)觸器(qi)的(de)額定電(dian)流不能低(di)于壓縮機銘牌上的(de)額定電(dian)流。

規格小或(huo)質(zhi)量低劣的(de)接(jie)觸(chu)(chu)(chu)器無(wu)法經受壓縮機啟動(dong)，堵轉和低電(dian)(dian)壓時(shi)的(de)大(da)電(dian)(dian)流(liu)沖擊，容(rong)易(yi)(yi)出現(xian)(xian)單(dan)相或(huo)多相觸(chu)(chu)(chu)點抖(dou)(dou)動(dong),焊接(jie)甚至脫落(luo)的(de)現(xian)(xian)象，引(yin)起電(dian)(dian)機損壞(huai)。觸(chu)(chu)(chu)點抖(dou)(dou)動(dong)的(de)接(jie)觸(chu)(chu)(chu)器頻繁地啟停電(dian)(dian)機。電(dian)(dian)機頻繁啟動(dong)，巨大(da)的(de)啟動(dong)電(dian)(dian)流(liu)和發熱,會加劇繞(rao)組(zu)(zu)絕緣層的(de)老化。每次(ci)啟動(dong)時(shi)，磁(ci)性力矩使電(dian)(dian)機繞(rao)組(zu)(zu)有微小的(de)移動(dong)和相互摩(mo)擦。如(ru)果有其它因素配(pei)合（如(ru)金屬屑，絕緣性差的(de)潤滑(hua)油等(deng)），很(hen)容(rong)易(yi)(yi)引(yin)起繞(rao)組(zu)(zu)間(jian)短路(lu)。熱保(bao)護系統并未設(she)計成能防止這種毀壞(huai)。此外，抖(dou)(dou)動(dong)的(de)接(jie)觸(chu)(chu)(chu)器線(xian)(xian)圈容(rong)易(yi)(yi)失效。如(ru)果有接(jie)觸(chu)(chu)(chu)線(xian)(xian)圈損壞(huai)，容(rong)易(yi)(yi)出現(xian)(xian)單(dan)相狀態。

如果接(jie)觸(chu)(chu)器(qi)(qi)選(xuan)型偏小，觸(chu)(chu)頭(tou)不能承受電(dian)弧和由于頻(pin)繁開停循環或不穩定控(kong)制(zhi)回(hui)路(lu)電(dian)壓(ya)產生的(de)(de)高溫，可能焊(han)(han)(han)合(he)或從觸(chu)(chu)頭(tou)架中脫落。焊(han)(han)(han)合(he)的(de)(de)觸(chu)(chu)頭(tou)將產生永久性(xing)單相狀態，使過(guo)載保護(hu)器(qi)(qi)持續地(di)循環接(jie)通和斷(duan)開，需要特別(bie)強調的(de)(de)是，接(jie)觸(chu)(chu)器(qi)(qi)觸(chu)(chu)點焊(han)(han)(han)合(he)后，依(yi)賴接(jie)觸(chu)(chu)器(qi)(qi)斷(duan)開壓(ya)縮機電(dian)源回(hui)路(lu)的(de)(de)所有控(kong)制(zhi)（比如高低壓(ya)控(kong)制(zhi)，油壓(ya)控(kong)制(zhi)，融霜控(kong)制(zhi)等）將全(quan)部(bu)失效，壓(ya)縮機處于無保護(hu)狀態。

因此(ci)，當電機燒毀后，檢(jian)查接(jie)觸器是(shi)必(bi)不可少(shao)的(de)工序。接(jie)觸器是(shi)導致電機損壞的(de)一個常(chang)常(chang)被(bei)人遺忘(wang)的(de)重要(yao)原(yuan)因。

五、電源缺相和電壓異常

電(dian)壓(ya)不(bu)正常和缺相(xiang)可(ke)以輕(qing)而易舉地毀掉任何電(dian)機。

電(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)壓(ya)(ya)變化范圍(wei)不(bu)(bu)(bu)(bu)(bu)(bu)能(neng)超過(guo)(guo)額定電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)的(de)(de)(de)(de)(de)(de)±10%。三(san)(san)相(xiang)(xiang)(xiang)(xiang)(xiang)間的(de)(de)(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)不(bu)(bu)(bu)(bu)(bu)(bu)平(ping)(ping)(ping)衡(heng)(heng)(heng)不(bu)(bu)(bu)(bu)(bu)(bu)能(neng)超過(guo)(guo)5％。大(da)功率(lv)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)必(bi)須獨立供電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)，以(yi)防(fang)同線(xian)其(qi)他(ta)大(da)功率(lv)設(she)備啟動(dong)和(he)運(yun)轉時造成(cheng)低電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)。電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)線(xian)必(bi)須能(neng)夠承載(zai)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)的(de)(de)(de)(de)(de)(de)額定電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)。如(ru)果發(fa)生缺(que)相(xiang)(xiang)(xiang)(xiang)(xiang)時壓(ya)(ya)縮機(ji)(ji)正(zheng)在運(yun)轉，它將繼續運(yun)行(xing)但(dan)會(hui)(hui)有(you)大(da)的(de)(de)(de)(de)(de)(de)負(fu)載(zai)電(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)機(ji)(ji)繞(rao)組(zu)會(hui)(hui)很(hen)快(kuai)過(guo)(guo)熱(re)(re)，正(zheng)常(chang)情況(kuang)下壓(ya)(ya)縮機(ji)(ji)會(hui)(hui)被熱(re)(re)保(bao)(bao)護。當電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)繞(rao)組(zu)冷(leng)卻至(zhi)設(she)定溫度(du)，接觸器(qi)會(hui)(hui)閉合，但(dan)壓(ya)(ya)縮機(ji)(ji)啟動(dong)不(bu)(bu)(bu)(bu)(bu)(bu)起(qi)來，出(chu)現堵轉，并進(jin)入“堵轉－熱(re)(re)保(bao)(bao)護－堵轉”死循環。現代電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)繞(rao)組(zu)的(de)(de)(de)(de)(de)(de)差別(bie)非常(chang)小，電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)三(san)(san)相(xiang)(xiang)(xiang)(xiang)(xiang)平(ping)(ping)(ping)衡(heng)(heng)(heng)時相(xiang)(xiang)(xiang)(xiang)(xiang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)的(de)(de)(de)(de)(de)(de)差別(bie)可以(yi)忽略。理想狀態下，相(xiang)(xiang)(xiang)(xiang)(xiang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)始終相(xiang)(xiang)(xiang)(xiang)(xiang)等(deng)，只要在任一(yi)相(xiang)(xiang)(xiang)(xiang)(xiang)上接一(yi)個保(bao)(bao)護器(qi)就可以(yi)防(fang)止過(guo)(guo)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)造成(cheng)的(de)(de)(de)(de)(de)(de)損壞。實際(ji)上很(hen)難保(bao)(bao)證(zheng)相(xiang)(xiang)(xiang)(xiang)(xiang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)的(de)(de)(de)(de)(de)(de)平(ping)(ping)(ping)衡(heng)(heng)(heng)。電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)不(bu)(bu)(bu)(bu)(bu)(bu)平(ping)(ping)(ping)衡(heng)(heng)(heng)百分(fen)(fen)(fen)數計算方法(fa)為(wei)，相(xiang)(xiang)(xiang)(xiang)(xiang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)與(yu)三(san)(san)相(xiang)(xiang)(xiang)(xiang)(xiang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)平(ping)(ping)(ping)均值(zhi)(zhi)的(de)(de)(de)(de)(de)(de)最大(da)偏(pian)差值(zhi)(zhi)與(yu)三(san)(san)相(xiang)(xiang)(xiang)(xiang)(xiang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)平(ping)(ping)(ping)均值(zhi)(zhi)比值(zhi)(zhi)。例(li)(li)如(ru)，標(biao)稱380V三(san)(san)相(xiang)(xiang)(xiang)(xiang)(xiang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)，在壓(ya)(ya)縮機(ji)(ji)接線(xian)端(duan)測量的(de)(de)(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)分(fen)(fen)(fen)別(bie)為(wei)380V、366V、400V。可以(yi)計算出(chu)三(san)(san)相(xiang)(xiang)(xiang)(xiang)(xiang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)平(ping)(ping)(ping)均值(zhi)(zhi)382V，最大(da)偏(pian)差為(wei)20V,所以(yi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)不(bu)(bu)(bu)(bu)(bu)(bu)平(ping)(ping)(ping)衡(heng)(heng)(heng)百分(fen)(fen)(fen)數為(wei)5.2％。作(zuo)為(wei)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)不(bu)(bu)(bu)(bu)(bu)(bu)平(ping)(ping)(ping)衡(heng)(heng)(heng)的(de)(de)(de)(de)(de)(de)結果，在正(zheng)常(chang)運(yun)行(xing)使負(fu)載(zai)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)的(de)(de)(de)(de)(de)(de)不(bu)(bu)(bu)(bu)(bu)(bu)平(ping)(ping)(ping)衡(heng)(heng)(heng)是電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)不(bu)(bu)(bu)(bu)(bu)(bu)平(ping)(ping)(ping)衡(heng)(heng)(heng)百分(fen)(fen)(fen)點(dian)數的(de)(de)(de)(de)(de)(de)4－10倍。前例(li)(li)中(zhong)，5.2％不(bu)(bu)(bu)(bu)(bu)(bu)平(ping)(ping)(ping)衡(heng)(heng)(heng)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)可能(neng)引起(qi)50％的(de)(de)(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)不(bu)(bu)(bu)(bu)(bu)(bu)平(ping)(ping)(ping)衡(heng)(heng)(heng)。美(mei)國(guo)國(guo)家電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)器(qi)制造商(shang)協會(hui)(hui)(NEMA)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)動(dong)機(ji)(ji)和(he)發(fa)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)標(biao)準出(chu)版物指出(chu)，由不(bu)(bu)(bu)(bu)(bu)(bu)平(ping)(ping)(ping)衡(heng)(heng)(heng)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)造成(cheng)的(de)(de)(de)(de)(de)(de)相(xiang)(xiang)(xiang)(xiang)(xiang)繞(rao)組(zu)溫升百分(fen)(fen)(fen)比大(da)約是電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)不(bu)(bu)(bu)(bu)(bu)(bu)平(ping)(ping)(ping)衡(heng)(heng)(heng)百分(fen)(fen)(fen)點(dian)數平(ping)(ping)(ping)方的(de)(de)(de)(de)(de)(de)兩倍。前例(li)(li)中(zhong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)不(bu)(bu)(bu)(bu)(bu)(bu)平(ping)(ping)(ping)衡(heng)(heng)(heng)點(dian)數為(wei)5.2，繞(rao)組(zu)溫度(du)增加的(de)(de)(de)(de)(de)(de)百分(fen)(fen)(fen)數為(wei)54％。結果是一(yi)相(xiang)(xiang)(xiang)(xiang)(xiang)繞(rao)組(zu)過(guo)(guo)熱(re)(re)而其(qi)他(ta)兩個繞(rao)組(zu)溫度(du)正(zheng)常(chang)。一(yi)份由U.L.(保(bao)(bao)險(xian)商(shang)實驗室，美(mei)國(guo))完成(cheng)的(de)(de)(de)(de)(de)(de)調(diao)查顯示，43％的(de)(de)(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)力公(gong)司允許(xu)3％的(de)(de)(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)不(bu)(bu)(bu)(bu)(bu)(bu)平(ping)(ping)(ping)衡(heng)(heng)(heng)，另有(you)30％的(de)(de)(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)力公(gong)司允許(xu)5％的(de)(de)(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)不(bu)(bu)(bu)(bu)(bu)(bu)平(ping)(ping)(ping)衡(heng)(heng)(heng)。

六、冷卻不足

功率較大的(de)壓縮(suo)機一般都是回氣冷卻型的(de)。蒸(zheng)發溫度越低，系統(tong)質量流往往越小。

當蒸發溫(wen)度(du)很低(di)時(shi)（超(chao)過制(zhi)造(zao)商(shang)的(de)(de)規定），流量就(jiu)不(bu)(bu)(bu)足以冷(leng)(leng)卻電機(ji)，電機(ji)就(jiu)會(hui)(hui)在較高溫(wen)度(du)下(xia)運轉。空氣冷(leng)(leng)卻型壓縮(suo)(suo)機(ji)（一般不(bu)(bu)(bu)超(chao)過10HP）對(dui)回(hui)氣的(de)(de)依賴性小，但對(dui)壓縮(suo)(suo)機(ji)環境溫(wen)度(du)和冷(leng)(leng)卻風(feng)量有明(ming)確(que)要(yao)(yao)求。制(zhi)冷(leng)(leng)劑(ji)大量泄漏也(ye)會(hui)(hui)造(zao)成系統(tong)質量流減(jian)小，電機(ji)的(de)(de)冷(leng)(leng)卻也(ye)會(hui)(hui)受(shou)到影響。一些無人看管的(de)(de)冷(leng)(leng)庫，往(wang)往(wang)要(yao)(yao)等到制(zhi)冷(leng)(leng)效果很差時(shi)才(cai)會(hui)(hui)發現制(zhi)冷(leng)(leng)劑(ji)大量泄漏了。電機(ji)過熱后會(hui)(hui)出現頻繁保(bao)護，有些用戶不(bu)(bu)(bu)深入檢查(cha)原因，甚至將熱保(bao)護器(qi)短路，那是非常糟糕的(de)(de)事情。過不(bu)(bu)(bu)了多(duo)久(jiu)，電機(ji)就(jiu)會(hui)(hui)燒掉。壓縮(suo)(suo)機(ji)都有安全(quan)運行(xing)工況范(fan)圍(wei)。安全(quan)工況主(zhu)要(yao)(yao)的(de)(de)考(kao)慮因素(su)就(jiu)是壓縮(suo)(suo)機(ji)和電機(ji)的(de)(de)負荷與(yu)冷(leng)(leng)卻。由于不(bu)(bu)(bu)同(tong)溫(wen)區(qu)的(de)(de)壓縮(suo)(suo)機(ji)的(de)(de)價格(ge)不(bu)(bu)(bu)同(tong)，過去國內冷(leng)(leng)凍行(xing)業超(chao)范(fan)圍(wei)使用壓縮(suo)(suo)機(ji)是比較常見的(de)(de)。隨著專業知識的(de)(de)增(zeng)長和經濟條(tiao)件的(de)(de)改善(shan)，情況已(yi)明(ming)顯改善(shan)。