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(xia)簡稱(cheng)壓縮機(ji)）的故障(zhang)可分為電機(ji)故障(zhang)和機(ji)械故障(zhang)（包括曲軸，連桿，活塞，閥片，缸蓋墊(dian)等）。

機械(xie)故障(zhang)往往使電機超負(fu)荷(he)運轉甚至堵轉，是電機損壞的主要(yao)原(yuan)因(yin)之一(yi)。

電(dian)機的(de)(de)損壞主要表現為定子繞組(zu)絕緣層(ceng)破壞（短路(lu)(lu)）和斷(duan)路(lu)(lu)等(deng)。定子繞組(zu)損壞后很難(nan)及時被發現，最終可能導(dao)(dao)致繞組(zu)燒(shao)毀。繞組(zu)燒(shao)毀后，掩蓋了一些(xie)導(dao)(dao)致燒(shao)毀的(de)(de)現象或直接(jie)原因(yin)(yin)，使得事后分析(xi)和原因(yin)(yin)調(diao)查比較困難(nan)。然而，電(dian)機的(de)(de)運轉離不開正常的(de)(de)電(dian)源輸入，合理的(de)(de)電(dian)機負荷(he)，良好的(de)(de)散熱和繞組(zu)漆包線絕緣層(ceng)的(de)(de)保(bao)護。

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

(1)異常負(fu)荷和堵轉；

(2)金屬屑引起的繞組(zu)短路；

(3)接觸(chu)器問題；

(4)電源缺相和電壓異(yi)常；

(5)冷卻不足(zu)；

(6)用壓縮機抽真空。

實際上，多種因素共同(tong)促(cu)成的(de)電(dian)機損壞更(geng)為常見。

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二、異常負荷和堵轉

電機(ji)負(fu)荷(he)包括(kuo)壓(ya)縮氣體所(suo)(suo)需負(fu)荷(he)以及克服機(ji)械(xie)摩擦所(suo)(suo)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(run)(run)(run)滑(hua)(hua)油(you)(you)(you)(you)(you)(you)過熱(re)，潤(run)(run)(run)滑(hua)(hua)油(you)(you)(you)(you)(you)(you)焦(jiao)化(hua)變(bian)質，以及缺油(you)(you)(you)(you)(you)(you)等都會(hui)破壞正常(chang)潤(run)(run)(run)滑(hua)(hua)，導致潤(run)(run)(run)滑(hua)(hua)失效(xiao)。回液(ye)稀釋潤(run)(run)(run)滑(hua)(hua)油(you)(you)(you)(you)(you)(you)，影響(xiang)摩(mo)擦面(mian)正常(chang)油(you)(you)(you)(you)(you)(you)膜的形成(cheng)，甚至沖刷掉(diao)原有油(you)(you)(you)(you)(you)(you)膜，增加(jia)(jia)摩(mo)擦和磨損。壓縮(suo)機過熱(re)會(hui)引起(qi)使(shi)潤(run)(run)(run)滑(hua)(hua)油(you)(you)(you)(you)(you)(you)高溫(wen)變(bian)稀甚至焦(jiao)化(hua)，影響(xiang)正常(chang)油(you)(you)(you)(you)(you)(you)膜的形成(cheng)。系統回油(you)(you)(you)(you)(you)(you)不好，壓縮(suo)機缺油(you)(you)(you)(you)(you)(you)，自然無法維持正常(chang)潤(run)(run)(run)滑(hua)(hua)。曲(qu)(qu)軸高速(su)旋轉，連桿活塞等高速(su)運動(dong)，沒有油(you)(you)(you)(you)(you)(you)膜保護(hu)的摩(mo)擦面(mian)會(hui)迅(xun)(xun)速(su)升溫(wen)，局(ju)部(bu)高溫(wen)使(shi)潤(run)(run)(run)滑(hua)(hua)油(you)(you)(you)(you)(you)(you)迅(xun)(xun)速(su)蒸發或焦(jiao)化(hua)，使(shi)該(gai)部(bu)位潤(run)(run)(run)滑(hua)(hua)更加(jia)(jia)困難，數秒鐘內可引起(qi)局(ju)部(bu)嚴重磨損。潤(run)(run)(run)滑(hua)(hua)失效(xiao)，局(ju)部(bu)磨損，使(shi)曲(qu)(qu)軸轉動(dong)需要更大力矩。

小(xiao)功(gong)率壓縮機(ji)(ji)（如冰(bing)箱，家用(yong)空調壓縮機(ji)(ji)）由于電機(ji)(ji)扭矩(ju)(ju)小(xiao)，潤滑失效(xiao)后常(chang)(chang)出現(xian)堵(du)轉(zhuan)(zhuan)(zhuan)（電機(ji)(ji)無法轉(zhuan)(zhuan)(zhuan)動(dong)）現(xian)象，并進入“堵(du)轉(zhuan)(zhuan)(zhuan)－熱保護(hu)－堵(du)轉(zhuan)(zhuan)(zhuan)”死循環，電機(ji)(ji)燒毀只(zhi)是時間問(wen)題。而大(da)功(gong)率半封(feng)閉壓縮機(ji)(ji)電機(ji)(ji)扭矩(ju)(ju)很(hen)大(da)，局(ju)部磨損不會(hui)(hui)引起(qi)堵(du)轉(zhuan)(zhuan)(zhuan)，電機(ji)(ji)功(gong)率會(hui)(hui)在一(yi)定范圍內隨(sui)負荷而增(zeng)(zeng)大(da)，從而引起(qi)更為嚴重的(de)(de)(de)磨損，甚至引起(qi)咬缸(gang)(gang)（活塞卡在氣缸(gang)(gang)內），連桿斷裂(lie)等嚴重損壞。堵(du)轉(zhuan)(zhuan)(zhuan)時的(de)(de)(de)電流(liu)(liu)(liu)(liu)（堵(du)轉(zhuan)(zhuan)(zhuan)電流(liu)(liu)(liu)(liu)）大(da)約(yue)是正常(chang)(chang)運行電流(liu)(liu)(liu)(liu)的(de)(de)(de)4－8倍。電機(ji)(ji)啟(qi)動(dong)瞬間，電流(liu)(liu)(liu)(liu)的(de)(de)(de)峰(feng)值可接近或達到堵(du)轉(zhuan)(zhuan)(zhuan)電流(liu)(liu)(liu)(liu)。由于電阻放(fang)熱量與電流(liu)(liu)(liu)(liu)的(de)(de)(de)平方成正比，啟(qi)動(dong)和(he)堵(du)轉(zhuan)(zhuan)(zhuan)時的(de)(de)(de)電流(liu)(liu)(liu)(liu)會(hui)(hui)使(shi)繞組(zu)迅(xun)速升溫。熱保護(hu)可以(yi)在堵(du)轉(zhuan)(zhuan)(zhuan)時保護(hu)電極，但一(yi)般不會(hui)(hui)有很(hen)快的(de)(de)(de)響應，不能阻止頻繁(fan)啟(qi)動(dong)等引起(qi)的(de)(de)(de)繞組(zu)溫度變化(hua)。頻繁(fan)啟(qi)動(dong)和(he)異常(chang)(chang)負荷，使(shi)繞組(zu)經(jing)受高(gao)溫考驗，會(hui)(hui)降(jiang)低(di)漆包線(xian)的(de)(de)(de)絕緣性能。此外，壓縮氣體所需(xu)負荷也(ye)會(hui)(hui)隨(sui)壓縮比增(zeng)(zeng)大(da)和(he)壓差增(zeng)(zeng)大(da)而增(zeng)(zeng)大(da)。

因(yin)此將高(gao)溫(wen)壓縮機用(yong)于(yu)低溫(wen)，或將低溫(wen)壓縮機用(yong)于(yu)高(gao)溫(wen)，都會(hui)影(ying)響(xiang)電(dian)機負荷和散熱，是不合適(shi)的，會(hui)縮短電(dian)極使(shi)用(yong)壽命。繞組絕緣(yuan)性能變差(cha)后，如果有其它因(yin)素(su)（如金屬屑構成導(dao)電(dian)回(hui)路，酸性潤(run)滑(hua)油等(deng)）配合，很容(rong)易引起短路而損(sun)壞(huai)。

三、金屬屑引起的繞組短路

繞組中夾雜(za)的(de)金屬(shu)屑是(shi)短路和接地(di)絕緣值低的(de)罪魁禍(huo)首。

壓縮機運轉時(shi)(shi)的(de)正常(chang)振動(dong)，以(yi)及每次啟動(dong)時(shi)(shi)繞(rao)組(zu)受(shou)電(dian)磁力作用而扭動(dong)，都會促使夾雜于(yu)繞(rao)組(zu)間(jian)的(de)金(jin)(jin)(jin)屬(shu)屑(xie)與(yu)繞(rao)組(zu)漆包線(xian)之間(jian)的(de)相對運動(dong)和(he)摩擦。棱角銳利的(de)金(jin)(jin)(jin)屬(shu)屑(xie)會劃傷漆包線(xian)絕(jue)緣(yuan)層(ceng)，引起短路(lu)。金(jin)(jin)(jin)屬(shu)屑(xie)的(de)來源包括施工時(shi)(shi)留下的(de)銅管(guan)屑(xie)，焊渣，壓(ya)(ya)(ya)(ya)縮(suo)(suo)機(ji)(ji)(ji)(ji)內部磨(mo)損(sun)(sun)和(he)零部件損(sun)(sun)壞（比如(ru)閥(fa)片(pian)破(po)碎(sui)）時(shi)(shi)掉下的(de)金(jin)(jin)(jin)屬(shu)屑(xie)等。對于(yu)全封(feng)閉(bi)壓(ya)(ya)(ya)(ya)縮(suo)(suo)機(ji)(ji)(ji)(ji)（包括全封(feng)閉(bi)渦旋壓(ya)(ya)(ya)(ya)縮(suo)(suo)機(ji)(ji)(ji)(ji)），這些(xie)(xie)金(jin)(jin)(jin)屬(shu)屑(xie)或碎(sui)粒會落(luo)在繞(rao)組(zu)上。對于(yu)半封(feng)閉(bi)壓(ya)(ya)(ya)(ya)縮(suo)(suo)機(ji)(ji)(ji)(ji)，有(you)些(xie)(xie)顆粒會隨氣體和(he)潤滑(hua)油(you)在系統(tong)中(zhong)流動(dong)，最(zui)后(hou)由于(yu)磁性聚集在繞(rao)組(zu)中(zhong)；而有(you)些(xie)(xie)金(jin)(jin)(jin)屬(shu)屑(xie)（比如(ru)軸承磨(mo)損(sun)(sun)以(yi)及電(dian)機(ji)(ji)(ji)(ji)轉子與(yu)定子磨(mo)損(sun)(sun)（掃膛）時(shi)(shi)產生(sheng)的(de)）會直接(jie)落(luo)在繞(rao)組(zu)上。繞(rao)組(zu)中(zhong)聚集了金(jin)(jin)(jin)屬(shu)屑(xie)后(hou)，發(fa)生(sheng)短路(lu)只(zhi)是(shi)一個時(shi)(shi)間(jian)問(wen)題。需要特別提請注意(yi)的(de)是(shi)雙級(ji)(ji)(ji)壓(ya)(ya)(ya)(ya)縮(suo)(suo)機(ji)(ji)(ji)(ji)。在雙級(ji)(ji)(ji)壓(ya)(ya)(ya)(ya)縮(suo)(suo)機(ji)(ji)(ji)(ji)中(zhong)，回(hui)(hui)氣以(yi)及正常(chang)的(de)回(hui)(hui)油(you)直接(jie)進入第一級(ji)(ji)(ji)（低(di)壓(ya)(ya)(ya)(ya)級(ji)(ji)(ji)）氣缸(gang)，壓(ya)(ya)(ya)(ya)縮(suo)(suo)后(hou)經中(zhong)壓(ya)(ya)(ya)(ya)管(guan)進入電(dian)機(ji)(ji)(ji)(ji)腔冷卻(que)繞(rao)組(zu)，然后(hou)和(he)普通單(dan)級(ji)(ji)(ji)壓(ya)(ya)(ya)(ya)縮(suo)(suo)機(ji)(ji)(ji)(ji)一樣，進入第二級(ji)(ji)(ji)（高(gao)壓(ya)(ya)(ya)(ya)級(ji)(ji)(ji)氣缸(gang)）。回(hui)(hui)氣中(zhong)帶(dai)有(you)潤滑(hua)油(you)，已經使壓(ya)(ya)(ya)(ya)縮(suo)(suo)過程如(ru)履薄冰(bing)，如(ru)果再有(you)回(hui)(hui)液，第一級(ji)(ji)(ji)氣缸(gang)的(de)閥(fa)片(pian)很容易(yi)被打碎(sui)。碎(sui)閥(fa)片(pian)經中(zhong)壓(ya)(ya)(ya)(ya)管(guan)后(hou)可進入繞(rao)組(zu)。因此，雙級(ji)(ji)(ji)壓(ya)(ya)(ya)(ya)縮(suo)(suo)機(ji)(ji)(ji)(ji)比單(dan)級(ji)(ji)(ji)壓(ya)(ya)(ya)(ya)縮(suo)(suo)機(ji)(ji)(ji)(ji)更容易(yi)出現金(jin)(jin)(jin)屬(shu)屑(xie)引起的(de)電(dian)機(ji)(ji)(ji)(ji)短路(lu)。

不幸的(de)(de)事情往(wang)往(wang)湊到一(yi)(yi)塊，出問題的(de)(de)壓縮機(ji)在開(kai)機(ji)分析(xi)時(shi)聞道(dao)的(de)(de)常(chang)常(chang)是潤(run)(run)(run)滑油(you)的(de)(de)焦(jiao)糊(hu)味。金屬面嚴重磨損時(shi)溫度(du)是很高的(de)(de)，而潤(run)(run)(run)滑油(you)在175?C以上(shang)時(shi)開(kai)始焦(jiao)化。系(xi)統(tong)中如果有較(jiao)多水分（真空抽得(de)不理想(xiang)，潤(run)(run)(run)滑油(you)和制冷劑含(han)水量大，負壓回氣管破裂后空氣進(jin)入等），潤(run)(run)(run)滑油(you)就可(ke)能出現酸性。酸性潤(run)(run)(run)滑油(you)會腐(fu)蝕銅管和繞(rao)組絕緣層，一(yi)(yi)方(fang)面，它(ta)會引起(qi)鍍銅現象(xiang)；另一(yi)(yi)方(fang)面，這種含(han)有銅原(yuan)子的(de)(de)酸性潤(run)(run)(run)滑油(you)的(de)(de)絕緣性能很差，為繞(rao)組短路提供了條件。

四、接觸器問題

接觸器是電機控制(zhi)回路中(zhong)重要(yao)部件之一，選型不合(he)理可以毀壞最(zui)好的壓(ya)縮機。

按(an)負(fu)載(zai)正確選擇(ze)接(jie)觸(chu)(chu)器是極其重要的(de)。接(jie)觸(chu)(chu)器必(bi)(bi)須(xu)能(neng)滿(man)足苛刻的(de)條件，如快速循環，持續(xu)超載(zai)和(he)低電壓(ya)。它們(men)必(bi)(bi)須(xu)有足夠大(da)的(de)面積以(yi)散發負(fu)載(zai)電流(liu)所產生的(de)熱量，觸(chu)(chu)點材(cai)料的(de)選擇(ze)必(bi)(bi)須(xu)在啟動或堵轉等大(da)電流(liu)情況下能(neng)防止焊合。為了安全(quan)可靠，壓(ya)縮(suo)機(ji)接(jie)觸(chu)(chu)器要同時(shi)斷開三相電路。谷輪(lun)公司(si)不(bu)推薦斷開二相電路的(de)方法。在美(mei)國，谷輪(lun)公司(si)認(ren)可的(de)接(jie)觸(chu)(chu)器必(bi)(bi)須(xu)滿(man)足如下四項(xiang)：

接(jie)觸(chu)器(qi)必須滿(man)足(zu)ARI標(biao)準780-78“專用接(jie)觸(chu)器(qi)標(biao)準”規定的(de)工作和測試準則。

制造商必須保證接觸器在室溫(wen)下(xia)，在最低銘(ming)牌電壓的80％時能(neng)閉(bi)合。

當使用單個(ge)接(jie)觸器(qi)時，接(jie)觸器(qi)額定電(dian)(dian)流必(bi)須大于電(dian)(dian)機銘牌電(dian)(dian)流額定值(zhi)(RLA).同(tong)時，接(jie)觸器(qi)必(bi)須能(neng)承(cheng)受電(dian)(dian)機堵轉電(dian)(dian)流。如果接(jie)觸器(qi)下(xia)游還有其它負載，比如電(dian)(dian)機風扇等，也必(bi)須考(kao)慮。

當使用(yong)兩個(ge)接觸(chu)器時(shi)，每(mei)個(ge)接觸(chu)器的(de)分繞組堵(du)轉(zhuan)額(e)定(ding)值必須(xu)等于(yu)或大于(yu)壓(ya)縮機(ji)半繞組堵(du)轉(zhuan)額(e)定(ding)值。

接觸器的額定電(dian)流(liu)(liu)不能低于壓縮機(ji)銘牌上的額定電(dian)流(liu)(liu)。

規格(ge)小或質量低(di)劣的(de)(de)接(jie)(jie)(jie)觸器無法經(jing)受壓縮機(ji)(ji)啟(qi)動(dong)(dong)(dong)，堵轉和(he)(he)低(di)電(dian)(dian)壓時(shi)的(de)(de)大電(dian)(dian)流沖(chong)擊，容(rong)易出現單相(xiang)或多相(xiang)觸點抖動(dong)(dong)(dong),焊接(jie)(jie)(jie)甚至脫(tuo)落的(de)(de)現象(xiang)，引起電(dian)(dian)機(ji)(ji)損(sun)壞。觸點抖動(dong)(dong)(dong)的(de)(de)接(jie)(jie)(jie)觸器頻(pin)繁地啟(qi)停電(dian)(dian)機(ji)(ji)。電(dian)(dian)機(ji)(ji)頻(pin)繁啟(qi)動(dong)(dong)(dong)，巨大的(de)(de)啟(qi)動(dong)(dong)(dong)電(dian)(dian)流和(he)(he)發(fa)熱,會加劇繞(rao)(rao)組(zu)絕(jue)緣層的(de)(de)老化。每次啟(qi)動(dong)(dong)(dong)時(shi)，磁(ci)性力矩使電(dian)(dian)機(ji)(ji)繞(rao)(rao)組(zu)有(you)(you)微(wei)小的(de)(de)移動(dong)(dong)(dong)和(he)(he)相(xiang)互摩(mo)擦。如(ru)(ru)果有(you)(you)其(qi)它因素配合（如(ru)(ru)金屬屑，絕(jue)緣性差的(de)(de)潤滑(hua)油等），很容(rong)易引起繞(rao)(rao)組(zu)間短路(lu)。熱保護系統并未(wei)設計成能防止這種毀壞。此外，抖動(dong)(dong)(dong)的(de)(de)接(jie)(jie)(jie)觸器線圈(quan)容(rong)易失效。如(ru)(ru)果有(you)(you)接(jie)(jie)(jie)觸線圈(quan)損(sun)壞，容(rong)易出現單相(xiang)狀態。

如果接觸(chu)器(qi)選型偏小，觸(chu)頭(tou)不能(neng)承受電弧和由(you)于頻繁(fan)開(kai)停循環或(huo)不穩定控(kong)(kong)(kong)制(zhi)回路電壓產生的(de)高溫(wen)，可能(neng)焊合(he)或(huo)從觸(chu)頭(tou)架(jia)中脫落。焊合(he)的(de)觸(chu)頭(tou)將產生永久性單相狀態，使過載保護器(qi)持續(xu)地循環接通(tong)和斷開(kai)，需(xu)要特別強(qiang)調的(de)是，接觸(chu)器(qi)觸(chu)點焊合(he)后，依(yi)賴接觸(chu)器(qi)斷開(kai)壓縮機(ji)電源回路的(de)所有控(kong)(kong)(kong)制(zhi)（比如高低壓控(kong)(kong)(kong)制(zhi)，油壓控(kong)(kong)(kong)制(zhi)，融霜(shuang)控(kong)(kong)(kong)制(zhi)等）將全部失效，壓縮機(ji)處于無保護狀態。

因此(ci)，當電(dian)機燒毀后，檢查(cha)接觸器是必不可少的工(gong)序。接觸器是導(dao)致電(dian)機損壞的一(yi)個常常被人遺忘(wang)的重要原因。

五、電源缺相和電壓異常

電壓不正常(chang)和(he)缺相可以輕而易舉地毀掉任何電機。

電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)變化范圍不(bu)(bu)(bu)(bu)(bu)能(neng)超過(guo)額定(ding)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)的(de)(de)±10%。三(san)(san)相(xiang)(xiang)(xiang)(xiang)間(jian)的(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)不(bu)(bu)(bu)(bu)(bu)平(ping)(ping)(ping)(ping)(ping)(ping)衡(heng)(heng)(heng)(heng)不(bu)(bu)(bu)(bu)(bu)能(neng)超過(guo)5％。大(da)(da)功(gong)率(lv)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)(ji)(ji)必須獨立供電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)，以防(fang)同線其他大(da)(da)功(gong)率(lv)設(she)備啟(qi)動和運(yun)轉(zhuan)時造(zao)成(cheng)(cheng)低電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)。電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)(ji)(ji)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)線必須能(neng)夠承載電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)(ji)(ji)的(de)(de)額定(ding)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)。如(ru)(ru)果發(fa)生(sheng)缺相(xiang)(xiang)(xiang)(xiang)時壓(ya)(ya)(ya)縮機(ji)(ji)(ji)(ji)正(zheng)(zheng)在(zai)運(yun)轉(zhuan)，它將(jiang)繼續運(yun)行但會(hui)有大(da)(da)的(de)(de)負載電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)。電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)(ji)(ji)繞(rao)(rao)(rao)組(zu)(zu)會(hui)很快過(guo)熱(re)，正(zheng)(zheng)常情(qing)況下壓(ya)(ya)(ya)縮機(ji)(ji)(ji)(ji)會(hui)被(bei)熱(re)保護。當電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)(ji)(ji)繞(rao)(rao)(rao)組(zu)(zu)冷(leng)卻至設(she)定(ding)溫(wen)度，接(jie)觸(chu)器會(hui)閉合(he)，但壓(ya)(ya)(ya)縮機(ji)(ji)(ji)(ji)啟(qi)動不(bu)(bu)(bu)(bu)(bu)起(qi)來(lai)，出現堵(du)轉(zhuan)，并進入(ru)“堵(du)轉(zhuan)－熱(re)保護－堵(du)轉(zhuan)”死循環。現代電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)(ji)(ji)繞(rao)(rao)(rao)組(zu)(zu)的(de)(de)差(cha)別非常小，電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)三(san)(san)相(xiang)(xiang)(xiang)(xiang)平(ping)(ping)(ping)(ping)(ping)(ping)衡(heng)(heng)(heng)(heng)時相(xiang)(xiang)(xiang)(xiang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)的(de)(de)差(cha)別可以忽略。理想狀態下，相(xiang)(xiang)(xiang)(xiang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)始終相(xiang)(xiang)(xiang)(xiang)等(deng)，只要在(zai)任一相(xiang)(xiang)(xiang)(xiang)上接(jie)一個保護器就(jiu)可以防(fang)止過(guo)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)造(zao)成(cheng)(cheng)的(de)(de)損壞(huai)。實(shi)際上很難(nan)保證相(xiang)(xiang)(xiang)(xiang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)的(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)不(bu)(bu)(bu)(bu)(bu)平(ping)(ping)(ping)(ping)(ping)(ping)衡(heng)(heng)(heng)(heng)百分數(shu)計算(suan)方(fang)(fang)法為，相(xiang)(xiang)(xiang)(xiang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)與三(san)(san)相(xiang)(xiang)(xiang)(xiang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)平(ping)(ping)(ping)(ping)(ping)(ping)均值(zhi)的(de)(de)最大(da)(da)偏(pian)(pian)差(cha)值(zhi)與三(san)(san)相(xiang)(xiang)(xiang)(xiang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)平(ping)(ping)(ping)(ping)(ping)(ping)均值(zhi)比(bi)值(zhi)。例如(ru)(ru)，標稱380V三(san)(san)相(xiang)(xiang)(xiang)(xiang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)，在(zai)壓(ya)(ya)(ya)縮機(ji)(ji)(ji)(ji)接(jie)線端(duan)測量的(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)分別為380V、366V、400V。可以計算(suan)出三(san)(san)相(xiang)(xiang)(xiang)(xiang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)平(ping)(ping)(ping)(ping)(ping)(ping)均值(zhi)382V，最大(da)(da)偏(pian)(pian)差(cha)為20V,所(suo)以電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)不(bu)(bu)(bu)(bu)(bu)平(ping)(ping)(ping)(ping)(ping)(ping)衡(heng)(heng)(heng)(heng)百分數(shu)為5.2％。作為電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)不(bu)(bu)(bu)(bu)(bu)平(ping)(ping)(ping)(ping)(ping)(ping)衡(heng)(heng)(heng)(heng)的(de)(de)結果，在(zai)正(zheng)(zheng)常運(yun)行使負載電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)的(de)(de)不(bu)(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)不(bu)(bu)(bu)(bu)(bu)平(ping)(ping)(ping)(ping)(ping)(ping)衡(heng)(heng)(heng)(heng)百分點(dian)數(shu)的(de)(de)4－10倍。前例中(zhong)，5.2％不(bu)(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)可能(neng)引(yin)起(qi)50％的(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)不(bu)(bu)(bu)(bu)(bu)平(ping)(ping)(ping)(ping)(ping)(ping)衡(heng)(heng)(heng)(heng)。美(mei)國(guo)國(guo)家電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)器制造(zao)商協會(hui)(NEMA)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)動機(ji)(ji)(ji)(ji)和發(fa)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)(ji)(ji)標準出版(ban)物指出，由不(bu)(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)造(zao)成(cheng)(cheng)的(de)(de)相(xiang)(xiang)(xiang)(xiang)繞(rao)(rao)(rao)組(zu)(zu)溫(wen)升百分比(bi)大(da)(da)約是(shi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)不(bu)(bu)(bu)(bu)(bu)平(ping)(ping)(ping)(ping)(ping)(ping)衡(heng)(heng)(heng)(heng)百分點(dian)數(shu)平(ping)(ping)(ping)(ping)(ping)(ping)方(fang)(fang)的(de)(de)兩(liang)倍。前例中(zhong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)不(bu)(bu)(bu)(bu)(bu)平(ping)(ping)(ping)(ping)(ping)(ping)衡(heng)(heng)(heng)(heng)點(dian)數(shu)為5.2，繞(rao)(rao)(rao)組(zu)(zu)溫(wen)度增加的(de)(de)百分數(shu)為54％。結果是(shi)一相(xiang)(xiang)(xiang)(xiang)繞(rao)(rao)(rao)組(zu)(zu)過(guo)熱(re)而其他兩(liang)個繞(rao)(rao)(rao)組(zu)(zu)溫(wen)度正(zheng)(zheng)常。一份由U.L.(保險商實(shi)驗室(shi)，美(mei)國(guo))完成(cheng)(cheng)的(de)(de)調查顯示(shi)，43％的(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)力公(gong)司允許(xu)3％的(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)不(bu)(bu)(bu)(bu)(bu)平(ping)(ping)(ping)(ping)(ping)(ping)衡(heng)(heng)(heng)(heng)，另有30％的(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)力公(gong)司允許(xu)5％的(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)不(bu)(bu)(bu)(bu)(bu)平(ping)(ping)(ping)(ping)(ping)(ping)衡(heng)(heng)(heng)(heng)。

六、冷卻不足

功率較大的(de)壓縮機一(yi)般都是回氣冷卻型的(de)。蒸發(fa)溫度越低，系統(tong)質量流(liu)往(wang)往(wang)越小(xiao)。

當蒸發溫(wen)(wen)度很低時（超過(guo)制(zhi)造(zao)商的(de)(de)(de)(de)(de)規定），流量(liang)就不足以冷(leng)卻電(dian)(dian)(dian)機(ji)(ji)，電(dian)(dian)(dian)機(ji)(ji)就會在較高溫(wen)(wen)度下運轉。空(kong)氣(qi)冷(leng)卻型壓縮(suo)(suo)機(ji)(ji)（一般不超過(guo)10HP）對回氣(qi)的(de)(de)(de)(de)(de)依賴(lai)性小，但對壓縮(suo)(suo)機(ji)(ji)環境溫(wen)(wen)度和(he)冷(leng)卻風量(liang)有(you)(you)明確要(yao)求(qiu)。制(zhi)冷(leng)劑大(da)量(liang)泄漏(lou)也(ye)會造(zao)成系(xi)統質量(liang)流減小，電(dian)(dian)(dian)機(ji)(ji)的(de)(de)(de)(de)(de)冷(leng)卻也(ye)會受到影(ying)響。一些(xie)無(wu)人(ren)看管的(de)(de)(de)(de)(de)冷(leng)庫，往往要(yao)等到制(zhi)冷(leng)效(xiao)果(guo)很差時才(cai)會發現(xian)制(zhi)冷(leng)劑大(da)量(liang)泄漏(lou)了(le)(le)。電(dian)(dian)(dian)機(ji)(ji)過(guo)熱后會出(chu)現(xian)頻繁(fan)保護，有(you)(you)些(xie)用戶不深入檢查原(yuan)因，甚(shen)至將熱保護器短(duan)路，那(nei)是(shi)(shi)非常(chang)糟糕的(de)(de)(de)(de)(de)事(shi)情。過(guo)不了(le)(le)多久，電(dian)(dian)(dian)機(ji)(ji)就會燒掉。壓縮(suo)(suo)機(ji)(ji)都有(you)(you)安全運行工(gong)況(kuang)范(fan)(fan)圍(wei)。安全工(gong)況(kuang)主要(yao)的(de)(de)(de)(de)(de)考慮因素就是(shi)(shi)壓縮(suo)(suo)機(ji)(ji)和(he)電(dian)(dian)(dian)機(ji)(ji)的(de)(de)(de)(de)(de)負荷(he)與冷(leng)卻。由于不同溫(wen)(wen)區的(de)(de)(de)(de)(de)壓縮(suo)(suo)機(ji)(ji)的(de)(de)(de)(de)(de)價格不同，過(guo)去(qu)國內冷(leng)凍(dong)行業(ye)(ye)超范(fan)(fan)圍(wei)使用壓縮(suo)(suo)機(ji)(ji)是(shi)(shi)比較常(chang)見的(de)(de)(de)(de)(de)。隨著(zhu)專業(ye)(ye)知(zhi)識的(de)(de)(de)(de)(de)增長和(he)經濟條件的(de)(de)(de)(de)(de)改善，情況(kuang)已(yi)明顯改善。