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（以下簡稱壓縮機）的故(gu)障可分(fen)為(wei)電機故(gu)障和機械(xie)故(gu)障（包括曲軸(zhou)，連桿，活塞，閥片，缸蓋墊等）。

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

電機(ji)(ji)的(de)(de)(de)損壞(huai)主要(yao)表現(xian)為定子繞(rao)(rao)(rao)(rao)組(zu)(zu)絕緣層破壞(huai)（短(duan)路）和(he)斷(duan)路等。定子繞(rao)(rao)(rao)(rao)組(zu)(zu)損壞(huai)后(hou)很難及(ji)時被(bei)發現(xian)，最(zui)終(zhong)可(ke)能(neng)導致繞(rao)(rao)(rao)(rao)組(zu)(zu)燒(shao)毀。繞(rao)(rao)(rao)(rao)組(zu)(zu)燒(shao)毀后(hou)，掩蓋了(le)一些(xie)導致燒(shao)毀的(de)(de)(de)現(xian)象(xiang)或直接(jie)原(yuan)因(yin)，使得事后(hou)分析和(he)原(yuan)因(yin)調查(cha)比(bi)較困難。然而，電機(ji)(ji)的(de)(de)(de)運轉離不開正常的(de)(de)(de)電源輸入，合理的(de)(de)(de)電機(ji)(ji)負荷，良好的(de)(de)(de)散熱和(he)繞(rao)(rao)(rao)(rao)組(zu)(zu)漆包線絕緣層的(de)(de)(de)保護。

從這幾方面入手，不(bu)難發現繞組燒毀的原因不(bu)外(wai)乎如下六種(zhong)：

(1)異常負荷和堵轉(zhuan)；

(2)金(jin)屬屑(xie)引起(qi)的繞(rao)組短路；

(3)接(jie)觸器問(wen)題(ti)；

(4)電源缺相和電壓異常；

(5)冷卻不足；

(6)用壓(ya)縮機抽(chou)真(zhen)空。

實際(ji)上，多種因素共同促成的(de)電(dian)機損壞更為(wei)常見。

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二、異常負荷和堵轉

電機負荷包括(kuo)壓縮氣體所需(xu)負荷以及(ji)克(ke)服機械(xie)摩擦所需(xu)負荷。

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)油(you)(you)過(guo)熱，潤(run)滑(hua)(hua)油(you)(you)焦(jiao)化(hua)變質，以(yi)及缺(que)(que)油(you)(you)等都會破(po)壞正常潤(run)滑(hua)(hua)，導致潤(run)滑(hua)(hua)失效。回液(ye)稀釋潤(run)滑(hua)(hua)油(you)(you)，影響摩擦(ca)面正常油(you)(you)膜的(de)形成，甚(shen)(shen)至沖刷掉原有油(you)(you)膜，增加(jia)摩擦(ca)和磨損(sun)。壓縮機過(guo)熱會引起使(shi)潤(run)滑(hua)(hua)油(you)(you)高溫變稀甚(shen)(shen)至焦(jiao)化(hua)，影響正常油(you)(you)膜的(de)形成。系統回油(you)(you)不好，壓縮機缺(que)(que)油(you)(you)，自然無法維持正常潤(run)滑(hua)(hua)。曲軸(zhou)高速(su)旋轉(zhuan)，連桿活塞等高速(su)運動，沒有油(you)(you)膜保護(hu)的(de)摩擦(ca)面會迅速(su)升溫，局部(bu)高溫使(shi)潤(run)滑(hua)(hua)油(you)(you)迅速(su)蒸發或焦(jiao)化(hua)，使(shi)該部(bu)位潤(run)滑(hua)(hua)更加(jia)困難，數秒鐘內可引起局部(bu)嚴(yan)重磨損(sun)。潤(run)滑(hua)(hua)失效，局部(bu)磨損(sun)，使(shi)曲軸(zhou)轉(zhuan)動需要更大力矩。

小(xiao)功(gong)率(lv)壓(ya)縮(suo)機(ji)(ji)（如冰箱(xiang)，家用空調壓(ya)縮(suo)機(ji)(ji)）由(you)于(yu)電(dian)(dian)(dian)機(ji)(ji)扭矩小(xiao)，潤滑失效后常(chang)出現(xian)堵(du)(du)轉（電(dian)(dian)(dian)機(ji)(ji)無法(fa)轉動(dong)）現(xian)象，并進入“堵(du)(du)轉－熱保護－堵(du)(du)轉”死循環，電(dian)(dian)(dian)機(ji)(ji)燒(shao)毀只是時(shi)間(jian)問題。而大(da)(da)功(gong)率(lv)半封(feng)閉壓(ya)縮(suo)機(ji)(ji)電(dian)(dian)(dian)機(ji)(ji)扭矩很大(da)(da)，局部磨(mo)損不(bu)會(hui)引起(qi)堵(du)(du)轉，電(dian)(dian)(dian)機(ji)(ji)功(gong)率(lv)會(hui)在一(yi)定范圍(wei)內隨負(fu)荷而增(zeng)大(da)(da)，從而引起(qi)更為嚴重的磨(mo)損，甚(shen)至引起(qi)咬(yao)缸（活塞卡在氣缸內），連桿斷裂等嚴重損壞。堵(du)(du)轉時(shi)的電(dian)(dian)(dian)流(liu)(liu)(liu)（堵(du)(du)轉電(dian)(dian)(dian)流(liu)(liu)(liu)）大(da)(da)約是正(zheng)常(chang)運(yun)行電(dian)(dian)(dian)流(liu)(liu)(liu)的4－8倍。電(dian)(dian)(dian)機(ji)(ji)啟(qi)(qi)動(dong)瞬間(jian)，電(dian)(dian)(dian)流(liu)(liu)(liu)的峰值可接近或達到堵(du)(du)轉電(dian)(dian)(dian)流(liu)(liu)(liu)。由(you)于(yu)電(dian)(dian)(dian)阻放熱量(liang)與電(dian)(dian)(dian)流(liu)(liu)(liu)的平方(fang)成正(zheng)比(bi)，啟(qi)(qi)動(dong)和(he)堵(du)(du)轉時(shi)的電(dian)(dian)(dian)流(liu)(liu)(liu)會(hui)使(shi)繞組(zu)(zu)迅速(su)升溫。熱保護可以在堵(du)(du)轉時(shi)保護電(dian)(dian)(dian)極，但(dan)一(yi)般不(bu)會(hui)有很快(kuai)的響(xiang)應，不(bu)能阻止頻(pin)(pin)繁(fan)啟(qi)(qi)動(dong)等引起(qi)的繞組(zu)(zu)溫度變化。頻(pin)(pin)繁(fan)啟(qi)(qi)動(dong)和(he)異(yi)常(chang)負(fu)荷，使(shi)繞組(zu)(zu)經受高溫考(kao)驗，會(hui)降低漆包(bao)線的絕(jue)緣性(xing)能。此外，壓(ya)縮(suo)氣體所需負(fu)荷也會(hui)隨壓(ya)縮(suo)比(bi)增(zeng)大(da)(da)和(he)壓(ya)差增(zeng)大(da)(da)而增(zeng)大(da)(da)。

因此(ci)將高溫(wen)(wen)壓縮(suo)機(ji)用(yong)于(yu)低溫(wen)(wen)，或將低溫(wen)(wen)壓縮(suo)機(ji)用(yong)于(yu)高溫(wen)(wen)，都會影響(xiang)電機(ji)負荷和散熱，是不合(he)適的(de)，會縮(suo)短(duan)電極使用(yong)壽命。繞(rao)組絕(jue)緣(yuan)性能變差后，如果有其它(ta)因素（如金屬屑構成導電回(hui)路，酸性潤(run)滑油等(deng)）配(pei)合(he)，很容易引起短(duan)路而損壞(huai)。

三、金屬屑引起的繞組短路

繞(rao)組中(zhong)夾雜的金屬屑是(shi)短路和接(jie)地(di)絕(jue)緣(yuan)值低(di)的罪魁禍(huo)首(shou)。

壓縮機運(yun)轉時(shi)(shi)的正(zheng)常(chang)振動(dong)(dong)，以及(ji)(ji)每次啟動(dong)(dong)時(shi)(shi)繞(rao)(rao)組(zu)(zu)(zu)受電磁(ci)力(li)作用而扭動(dong)(dong)，都會(hui)(hui)促使夾雜于(yu)繞(rao)(rao)組(zu)(zu)(zu)間的金屬(shu)(shu)屑(xie)與(yu)繞(rao)(rao)組(zu)(zu)(zu)漆包(bao)(bao)線之間的相對運(yun)動(dong)(dong)和(he)(he)摩(mo)擦。棱角(jiao)銳(rui)利的金屬(shu)(shu)屑(xie)會(hui)(hui)劃傷漆包(bao)(bao)線絕緣層，引起(qi)短(duan)路。金屬(shu)(shu)屑(xie)的來源包(bao)(bao)括(kuo)施工時(shi)(shi)留下的銅管(guan)屑(xie)，焊渣，壓(ya)(ya)(ya)縮(suo)(suo)機(ji)(ji)內部(bu)磨(mo)損和(he)(he)零部(bu)件損壞（比如(ru)閥片破碎）時(shi)(shi)掉(diao)下的金屬(shu)(shu)屑(xie)等。對于(yu)全(quan)封閉(bi)壓(ya)(ya)(ya)縮(suo)(suo)機(ji)(ji)（包(bao)(bao)括(kuo)全(quan)封閉(bi)渦旋(xuan)壓(ya)(ya)(ya)縮(suo)(suo)機(ji)(ji)），這些金屬(shu)(shu)屑(xie)或碎粒會(hui)(hui)落(luo)在繞(rao)(rao)組(zu)(zu)(zu)上。對于(yu)半封閉(bi)壓(ya)(ya)(ya)縮(suo)(suo)機(ji)(ji)，有些顆粒會(hui)(hui)隨氣(qi)體(ti)和(he)(he)潤(run)滑油在系統中流動(dong)(dong)，最后(hou)由于(yu)磁(ci)性聚(ju)(ju)集(ji)在繞(rao)(rao)組(zu)(zu)(zu)中；而有些金屬(shu)(shu)屑(xie)（比如(ru)軸承磨(mo)損以及(ji)(ji)電機(ji)(ji)轉子與(yu)定子磨(mo)損（掃膛(tang)）時(shi)(shi)產(chan)生的）會(hui)(hui)直接落(luo)在繞(rao)(rao)組(zu)(zu)(zu)上。繞(rao)(rao)組(zu)(zu)(zu)中聚(ju)(ju)集(ji)了(le)金屬(shu)(shu)屑(xie)后(hou)，發生短(duan)路只是一(yi)個時(shi)(shi)間問(wen)題。需要特別提請注意的是雙級(ji)壓(ya)(ya)(ya)縮(suo)(suo)機(ji)(ji)。在雙級(ji)壓(ya)(ya)(ya)縮(suo)(suo)機(ji)(ji)中，回氣(qi)以及(ji)(ji)正(zheng)常(chang)的回油直接進(jin)入(ru)第(di)(di)(di)一(yi)級(ji)（低壓(ya)(ya)(ya)級(ji)）氣(qi)缸，壓(ya)(ya)(ya)縮(suo)(suo)后(hou)經中壓(ya)(ya)(ya)管(guan)進(jin)入(ru)電機(ji)(ji)腔冷卻繞(rao)(rao)組(zu)(zu)(zu)，然后(hou)和(he)(he)普通(tong)單(dan)級(ji)壓(ya)(ya)(ya)縮(suo)(suo)機(ji)(ji)一(yi)樣，進(jin)入(ru)第(di)(di)(di)二(er)級(ji)（高壓(ya)(ya)(ya)級(ji)氣(qi)缸）。回氣(qi)中帶有潤(run)滑油，已經使壓(ya)(ya)(ya)縮(suo)(suo)過程如(ru)履薄冰，如(ru)果再(zai)有回液，第(di)(di)(di)一(yi)級(ji)氣(qi)缸的閥片很(hen)容易被打碎。碎閥片經中壓(ya)(ya)(ya)管(guan)后(hou)可進(jin)入(ru)繞(rao)(rao)組(zu)(zu)(zu)。因此，雙級(ji)壓(ya)(ya)(ya)縮(suo)(suo)機(ji)(ji)比單(dan)級(ji)壓(ya)(ya)(ya)縮(suo)(suo)機(ji)(ji)更(geng)容易出現金屬(shu)(shu)屑(xie)引起(qi)的電機(ji)(ji)短(duan)路。

不幸的(de)事情往(wang)往(wang)湊到一塊，出問題的(de)壓縮機在開機分析時(shi)聞道(dao)的(de)常常是(shi)潤(run)(run)滑(hua)油(you)(you)的(de)焦糊味。金屬面(mian)嚴重磨損時(shi)溫度是(shi)很高的(de)，而潤(run)(run)滑(hua)油(you)(you)在175?C以上時(shi)開始焦化。系(xi)統中如果(guo)有(you)較多水分（真(zhen)空抽(chou)得不理想，潤(run)(run)滑(hua)油(you)(you)和制冷(leng)劑含(han)水量大(da)，負壓回氣管破(po)裂后空氣進入等），潤(run)(run)滑(hua)油(you)(you)就可(ke)能(neng)出現(xian)酸性(xing)。酸性(xing)潤(run)(run)滑(hua)油(you)(you)會腐蝕銅(tong)管和繞組(zu)(zu)絕(jue)緣層(ceng)，一方(fang)面(mian)，它會引起鍍銅(tong)現(xian)象；另(ling)一方(fang)面(mian)，這(zhe)種(zhong)含(han)有(you)銅(tong)原子的(de)酸性(xing)潤(run)(run)滑(hua)油(you)(you)的(de)絕(jue)緣性(xing)能(neng)很差(cha)，為繞組(zu)(zu)短路(lu)提供了條件。

四、接觸器問題

接觸器是電機控制回路中重要部件之一，選型(xing)不合理可以(yi)毀壞最(zui)好的壓縮機。

按負載(zai)正確(que)選擇接(jie)觸器(qi)(qi)是(shi)極其重要(yao)的(de)(de)。接(jie)觸器(qi)(qi)必(bi)須能滿(man)足苛刻的(de)(de)條件，如快速(su)循環，持(chi)續超載(zai)和低電壓。它(ta)們必(bi)須有足夠大(da)的(de)(de)面積以散發負載(zai)電流(liu)所產生的(de)(de)熱量(liang)，觸點材料的(de)(de)選擇必(bi)須在啟動或堵(du)轉等(deng)大(da)電流(liu)情況(kuang)下能防止焊合。為了安全可靠，壓縮機接(jie)觸器(qi)(qi)要(yao)同時斷開三相電路。谷輪公司不推薦斷開二相電路的(de)(de)方法。在美國，谷輪公司認可的(de)(de)接(jie)觸器(qi)(qi)必(bi)須滿(man)足如下四項(xiang)：

接觸器必須(xu)滿足ARI標準(zhun)780-78“專用接觸器標準(zhun)”規定的工作和測試準(zhun)則(ze)。

制造商必須保證接觸(chu)器(qi)在(zai)室(shi)溫下，在(zai)最低銘牌電壓的80％時能閉合。

當使用(yong)單(dan)個接觸器時(shi)，接觸器額定電(dian)(dian)(dian)流必須(xu)大于電(dian)(dian)(dian)機(ji)銘牌(pai)電(dian)(dian)(dian)流額定值(RLA).同時(shi)，接觸器必須(xu)能承受電(dian)(dian)(dian)機(ji)堵轉電(dian)(dian)(dian)流。如果接觸器下游還有(you)其(qi)它負載(zai)，比如電(dian)(dian)(dian)機(ji)風(feng)扇等，也必須(xu)考慮。

當(dang)使用兩個(ge)接(jie)觸器時(shi)，每個(ge)接(jie)觸器的分繞組(zu)堵轉(zhuan)額定(ding)值(zhi)(zhi)必須等于或大(da)于壓縮機半繞組(zu)堵轉(zhuan)額定(ding)值(zhi)(zhi)。

接觸器的額定電(dian)(dian)流不能低于壓縮機銘牌上(shang)的額定電(dian)(dian)流。

規格(ge)小或(huo)質量低(di)劣的(de)接(jie)觸(chu)(chu)器(qi)無法經受壓縮機(ji)(ji)啟動，堵轉和低(di)電壓時(shi)的(de)大電流沖擊，容易(yi)(yi)出現單相(xiang)或(huo)多(duo)相(xiang)觸(chu)(chu)點抖動,焊接(jie)甚至脫落的(de)現象，引(yin)起(qi)電機(ji)(ji)損壞。觸(chu)(chu)點抖動的(de)接(jie)觸(chu)(chu)器(qi)頻(pin)繁(fan)地啟停電機(ji)(ji)。電機(ji)(ji)頻(pin)繁(fan)啟動，巨(ju)大的(de)啟動電流和發熱(re),會加(jia)劇繞組(zu)絕(jue)緣層(ceng)的(de)老化(hua)。每(mei)次啟動時(shi)，磁性力矩(ju)使(shi)電機(ji)(ji)繞組(zu)有(you)微小的(de)移動和相(xiang)互摩擦。如(ru)果(guo)有(you)其它因(yin)素(su)配合（如(ru)金(jin)屬屑，絕(jue)緣性差(cha)的(de)潤滑(hua)油等），很容易(yi)(yi)引(yin)起(qi)繞組(zu)間(jian)短路。熱(re)保護系統(tong)并未設(she)計成能防止(zhi)這種毀(hui)壞。此(ci)外，抖動的(de)接(jie)觸(chu)(chu)器(qi)線圈容易(yi)(yi)失效。如(ru)果(guo)有(you)接(jie)觸(chu)(chu)線圈損壞，容易(yi)(yi)出現單相(xiang)狀態(tai)。

如果接(jie)觸(chu)器(qi)(qi)選型偏小，觸(chu)頭(tou)不(bu)能承受(shou)電(dian)弧和由于頻繁開停(ting)循(xun)環或不(bu)穩(wen)定控制(zhi)(zhi)回(hui)路電(dian)壓(ya)產生的高溫，可能焊合(he)或從觸(chu)頭(tou)架中(zhong)脫落。焊合(he)的觸(chu)頭(tou)將(jiang)產生永久性(xing)單(dan)相狀(zhuang)態(tai)，使過載保護(hu)器(qi)(qi)持續地循(xun)環接(jie)通和斷(duan)開，需(xu)要特別強調(diao)的是，接(jie)觸(chu)器(qi)(qi)觸(chu)點焊合(he)后，依賴接(jie)觸(chu)器(qi)(qi)斷(duan)開壓(ya)縮(suo)機(ji)電(dian)源回(hui)路的所有(you)控制(zhi)(zhi)（比如高低壓(ya)控制(zhi)(zhi)，油壓(ya)控制(zhi)(zhi)，融霜控制(zhi)(zhi)等）將(jiang)全部失效，壓(ya)縮(suo)機(ji)處于無保護(hu)狀(zhuang)態(tai)。

因(yin)此，當電(dian)機燒毀后，檢查接觸器是必不可少的(de)工序。接觸器是導致電(dian)機損壞的(de)一個常常被人遺忘的(de)重要原因(yin)。

五、電源缺相和電壓異常

電壓不正常(chang)和缺(que)相可以輕(qing)而易(yi)舉地(di)毀掉(diao)任何電機。

電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)變化(hua)范(fan)圍不(bu)(bu)(bu)(bu)能超(chao)(chao)過額(e)定(ding)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)的(de)(de)(de)(de)(de)(de)±10%。三(san)(san)(san)相(xiang)間(jian)的(de)(de)(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)不(bu)(bu)(bu)(bu)平(ping)(ping)(ping)(ping)(ping)衡(heng)(heng)不(bu)(bu)(bu)(bu)能超(chao)(chao)過5％。大功(gong)率(lv)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)必須獨立供(gong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)，以(yi)防(fang)同線(xian)其他(ta)大功(gong)率(lv)設備(bei)啟動和(he)運(yun)(yun)轉(zhuan)時造成(cheng)低(di)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)。電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)線(xian)必須能夠承載電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)的(de)(de)(de)(de)(de)(de)額(e)定(ding)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)。如(ru)果(guo)發生缺相(xiang)時壓(ya)(ya)(ya)縮(suo)機(ji)(ji)正(zheng)在(zai)運(yun)(yun)轉(zhuan)，它將(jiang)繼續運(yun)(yun)行(xing)但會(hui)有(you)大的(de)(de)(de)(de)(de)(de)負(fu)載電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)。電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)繞(rao)(rao)組(zu)(zu)會(hui)很(hen)快過熱(re)，正(zheng)常情況下壓(ya)(ya)(ya)縮(suo)機(ji)(ji)會(hui)被熱(re)保(bao)護(hu)。當電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)繞(rao)(rao)組(zu)(zu)冷卻至(zhi)設定(ding)溫度，接觸器會(hui)閉(bi)合，但壓(ya)(ya)(ya)縮(suo)機(ji)(ji)啟動不(bu)(bu)(bu)(bu)起來，出現(xian)堵(du)轉(zhuan)，并(bing)進入“堵(du)轉(zhuan)－熱(re)保(bao)護(hu)－堵(du)轉(zhuan)”死(si)循環。現(xian)代電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)繞(rao)(rao)組(zu)(zu)的(de)(de)(de)(de)(de)(de)差(cha)別非常小，電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)三(san)(san)(san)相(xiang)平(ping)(ping)(ping)(ping)(ping)衡(heng)(heng)時相(xiang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)的(de)(de)(de)(de)(de)(de)差(cha)別可以(yi)忽略。理(li)想狀態下，相(xiang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)始終相(xiang)等，只(zhi)要在(zai)任一(yi)相(xiang)上接一(yi)個(ge)(ge)保(bao)護(hu)器就可以(yi)防(fang)止過電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)造成(cheng)的(de)(de)(de)(de)(de)(de)損(sun)壞(huai)。實際上很(hen)難保(bao)證相(xiang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)的(de)(de)(de)(de)(de)(de)平(ping)(ping)(ping)(ping)(ping)衡(heng)(heng)。電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)不(bu)(bu)(bu)(bu)平(ping)(ping)(ping)(ping)(ping)衡(heng)(heng)百分(fen)(fen)數(shu)計(ji)算(suan)方法為(wei)，相(xiang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)與三(san)(san)(san)相(xiang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)平(ping)(ping)(ping)(ping)(ping)均值(zhi)(zhi)的(de)(de)(de)(de)(de)(de)最大偏差(cha)值(zhi)(zhi)與三(san)(san)(san)相(xiang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)平(ping)(ping)(ping)(ping)(ping)均值(zhi)(zhi)比值(zhi)(zhi)。例(li)如(ru)，標(biao)稱380V三(san)(san)(san)相(xiang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)，在(zai)壓(ya)(ya)(ya)縮(suo)機(ji)(ji)接線(xian)端測量(liang)的(de)(de)(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)分(fen)(fen)別為(wei)380V、366V、400V。可以(yi)計(ji)算(suan)出三(san)(san)(san)相(xiang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)平(ping)(ping)(ping)(ping)(ping)均值(zhi)(zhi)382V，最大偏差(cha)為(wei)20V,所以(yi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)不(bu)(bu)(bu)(bu)平(ping)(ping)(ping)(ping)(ping)衡(heng)(heng)百分(fen)(fen)數(shu)為(wei)5.2％。作為(wei)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)不(bu)(bu)(bu)(bu)平(ping)(ping)(ping)(ping)(ping)衡(heng)(heng)的(de)(de)(de)(de)(de)(de)結果(guo)，在(zai)正(zheng)常運(yun)(yun)行(xing)使負(fu)載電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)的(de)(de)(de)(de)(de)(de)不(bu)(bu)(bu)(bu)平(ping)(ping)(ping)(ping)(ping)衡(heng)(heng)是(shi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)不(bu)(bu)(bu)(bu)平(ping)(ping)(ping)(ping)(ping)衡(heng)(heng)百分(fen)(fen)點數(shu)的(de)(de)(de)(de)(de)(de)4－10倍。前例(li)中(zhong)，5.2％不(bu)(bu)(bu)(bu)平(ping)(ping)(ping)(ping)(ping)衡(heng)(heng)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)可能引起50％的(de)(de)(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)(liu)(liu)不(bu)(bu)(bu)(bu)平(ping)(ping)(ping)(ping)(ping)衡(heng)(heng)。美國(guo)國(guo)家電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)器制(zhi)造商協會(hui)(NEMA)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)動機(ji)(ji)和(he)發電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)標(biao)準出版物指出，由不(bu)(bu)(bu)(bu)平(ping)(ping)(ping)(ping)(ping)衡(heng)(heng)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)造成(cheng)的(de)(de)(de)(de)(de)(de)相(xiang)繞(rao)(rao)組(zu)(zu)溫升百分(fen)(fen)比大約是(shi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)不(bu)(bu)(bu)(bu)平(ping)(ping)(ping)(ping)(ping)衡(heng)(heng)百分(fen)(fen)點數(shu)平(ping)(ping)(ping)(ping)(ping)方的(de)(de)(de)(de)(de)(de)兩(liang)倍。前例(li)中(zhong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)不(bu)(bu)(bu)(bu)平(ping)(ping)(ping)(ping)(ping)衡(heng)(heng)點數(shu)為(wei)5.2，繞(rao)(rao)組(zu)(zu)溫度增加(jia)的(de)(de)(de)(de)(de)(de)百分(fen)(fen)數(shu)為(wei)54％。結果(guo)是(shi)一(yi)相(xiang)繞(rao)(rao)組(zu)(zu)過熱(re)而其他(ta)兩(liang)個(ge)(ge)繞(rao)(rao)組(zu)(zu)溫度正(zheng)常。一(yi)份由U.L.(保(bao)險商實驗(yan)室，美國(guo))完(wan)成(cheng)的(de)(de)(de)(de)(de)(de)調查顯示，43％的(de)(de)(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)力公司(si)允(yun)許3％的(de)(de)(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)不(bu)(bu)(bu)(bu)平(ping)(ping)(ping)(ping)(ping)衡(heng)(heng)，另有(you)30％的(de)(de)(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)力公司(si)允(yun)許5％的(de)(de)(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)不(bu)(bu)(bu)(bu)平(ping)(ping)(ping)(ping)(ping)衡(heng)(heng)。

六、冷卻不足

功率較(jiao)大(da)的壓縮機一般都是回氣冷卻型(xing)的。蒸發溫度越低，系統質量流往往越小。

當蒸發溫度(du)很(hen)低時（超(chao)過(guo)制(zhi)造商的(de)(de)規定），流量(liang)就(jiu)不(bu)足(zu)以冷(leng)卻(que)電機(ji)(ji)，電機(ji)(ji)就(jiu)會在較高溫度(du)下運轉。空(kong)氣(qi)冷(leng)卻(que)型壓(ya)縮(suo)機(ji)(ji)（一般不(bu)超(chao)過(guo)10HP）對回(hui)氣(qi)的(de)(de)依賴性(xing)小，但對壓(ya)縮(suo)機(ji)(ji)環境溫度(du)和冷(leng)卻(que)風量(liang)有(you)(you)明確要(yao)求(qiu)。制(zhi)冷(leng)劑(ji)大量(liang)泄漏也(ye)會造成系統質量(liang)流減小，電機(ji)(ji)的(de)(de)冷(leng)卻(que)也(ye)會受到影響。一些(xie)無人看管的(de)(de)冷(leng)庫，往往要(yao)等到制(zhi)冷(leng)效(xiao)果(guo)很(hen)差時才會發現(xian)制(zhi)冷(leng)劑(ji)大量(liang)泄漏了。電機(ji)(ji)過(guo)熱后(hou)會出現(xian)頻繁保(bao)護，有(you)(you)些(xie)用戶不(bu)深入檢查原因(yin)，甚至將熱保(bao)護器(qi)短(duan)路，那(nei)是非常糟(zao)糕的(de)(de)事情。過(guo)不(bu)了多久，電機(ji)(ji)就(jiu)會燒掉。壓(ya)縮(suo)機(ji)(ji)都有(you)(you)安(an)全運行(xing)工況范(fan)圍。安(an)全工況主要(yao)的(de)(de)考慮因(yin)素就(jiu)是壓(ya)縮(suo)機(ji)(ji)和電機(ji)(ji)的(de)(de)負荷與(yu)冷(leng)卻(que)。由于(yu)不(bu)同溫區的(de)(de)壓(ya)縮(suo)機(ji)(ji)的(de)(de)價(jia)格不(bu)同，過(guo)去(qu)國內冷(leng)凍(dong)行(xing)業(ye)超(chao)范(fan)圍使用壓(ya)縮(suo)機(ji)(ji)是比較常見的(de)(de)。隨著專業(ye)知(zhi)識的(de)(de)增(zeng)長(chang)和經濟條(tiao)件的(de)(de)改善，情況已明顯改善。