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(ji)）的故障(zhang)可分為電機(ji)故障(zhang)和(he)機(ji)械故障(zhang)（包括曲(qu)軸，連桿，活塞，閥片，缸蓋墊等）。

機械故障往往使電(dian)機超負荷運(yun)轉甚至堵轉，是電(dian)機損(sun)壞的主要原(yuan)因之一。

電機的(de)損(sun)壞(huai)主要表現(xian)為定子繞(rao)(rao)(rao)(rao)組(zu)(zu)(zu)絕緣層破(po)壞(huai)（短路(lu)）和(he)(he)斷路(lu)等。定子繞(rao)(rao)(rao)(rao)組(zu)(zu)(zu)損(sun)壞(huai)后很難及時被(bei)發現(xian)，最終可能(neng)導致繞(rao)(rao)(rao)(rao)組(zu)(zu)(zu)燒毀(hui)。繞(rao)(rao)(rao)(rao)組(zu)(zu)(zu)燒毀(hui)后，掩蓋了一些導致燒毀(hui)的(de)現(xian)象或直接原(yuan)因，使(shi)得事后分析(xi)和(he)(he)原(yuan)因調查比較困難。然而(er)，電機的(de)運(yun)轉離不開(kai)正常的(de)電源輸入，合理的(de)電機負荷，良好(hao)的(de)散熱和(he)(he)繞(rao)(rao)(rao)(rao)組(zu)(zu)(zu)漆包線(xian)絕緣層的(de)保護。

從(cong)這幾方(fang)面入手，不難發現繞組燒毀的原因不外乎如下六種：

(1)異常負荷和堵轉(zhuan)；

(2)金(jin)屬屑引起的繞組短路；

(3)接(jie)觸器問題；

(4)電源缺相和電壓(ya)異常；

(5)冷(leng)卻不足；

(6)用壓(ya)縮機抽真空(kong)。

實際上，多種因素共(gong)同促成的電機損壞更為常見。

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二、異常負荷和堵轉

電(dian)機負荷(he)包括壓縮氣(qi)體所需(xu)負荷(he)以及(ji)克服機械(xie)摩擦所需(xu)負荷(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)(hua)油(you)(you)(you)過(guo)熱，潤(run)(run)(run)滑(hua)(hua)(hua)油(you)(you)(you)焦化變(bian)質(zhi)，以及(ji)缺油(you)(you)(you)等都(dou)會破壞正(zheng)常(chang)(chang)潤(run)(run)(run)滑(hua)(hua)(hua)，導致潤(run)(run)(run)滑(hua)(hua)(hua)失效。回(hui)液稀釋潤(run)(run)(run)滑(hua)(hua)(hua)油(you)(you)(you)，影響(xiang)摩(mo)擦(ca)面正(zheng)常(chang)(chang)油(you)(you)(you)膜(mo)的形成(cheng)，甚至沖刷掉原有(you)油(you)(you)(you)膜(mo)，增加(jia)摩(mo)擦(ca)和磨(mo)損(sun)。壓縮(suo)機過(guo)熱會引起使(shi)潤(run)(run)(run)滑(hua)(hua)(hua)油(you)(you)(you)高(gao)溫變(bian)稀甚至焦化，影響(xiang)正(zheng)常(chang)(chang)油(you)(you)(you)膜(mo)的形成(cheng)。系統(tong)回(hui)油(you)(you)(you)不好，壓縮(suo)機缺油(you)(you)(you)，自(zi)然無法維持正(zheng)常(chang)(chang)潤(run)(run)(run)滑(hua)(hua)(hua)。曲軸(zhou)(zhou)高(gao)速(su)旋轉(zhuan)，連桿(gan)活(huo)塞等高(gao)速(su)運動(dong)(dong)，沒有(you)油(you)(you)(you)膜(mo)保護的摩(mo)擦(ca)面會迅(xun)速(su)升溫，局(ju)(ju)部高(gao)溫使(shi)潤(run)(run)(run)滑(hua)(hua)(hua)油(you)(you)(you)迅(xun)速(su)蒸(zheng)發或焦化，使(shi)該部位潤(run)(run)(run)滑(hua)(hua)(hua)更加(jia)困難，數秒(miao)鐘內(nei)可(ke)引起局(ju)(ju)部嚴重磨(mo)損(sun)。潤(run)(run)(run)滑(hua)(hua)(hua)失效，局(ju)(ju)部磨(mo)損(sun)，使(shi)曲軸(zhou)(zhou)轉(zhuan)動(dong)(dong)需要更大力矩(ju)。

小功(gong)率(lv)壓(ya)縮機(ji)(ji)（如(ru)冰箱，家(jia)用(yong)空(kong)調(diao)壓(ya)縮機(ji)(ji)）由(you)于電(dian)(dian)(dian)(dian)機(ji)(ji)扭矩小，潤(run)滑失效(xiao)后常(chang)出現堵(du)轉(zhuan)(zhuan)(zhuan)(zhuan)（電(dian)(dian)(dian)(dian)機(ji)(ji)無法轉(zhuan)(zhuan)(zhuan)(zhuan)動(dong)）現象(xiang)，并(bing)進(jin)入“堵(du)轉(zhuan)(zhuan)(zhuan)(zhuan)－熱保護(hu)－堵(du)轉(zhuan)(zhuan)(zhuan)(zhuan)”死循(xun)環，電(dian)(dian)(dian)(dian)機(ji)(ji)燒毀(hui)只是(shi)時(shi)(shi)間(jian)問題。而大(da)功(gong)率(lv)半(ban)封閉壓(ya)縮機(ji)(ji)電(dian)(dian)(dian)(dian)機(ji)(ji)扭矩很(hen)大(da)，局部磨損(sun)不(bu)會(hui)(hui)(hui)引起(qi)(qi)堵(du)轉(zhuan)(zhuan)(zhuan)(zhuan)，電(dian)(dian)(dian)(dian)機(ji)(ji)功(gong)率(lv)會(hui)(hui)(hui)在(zai)一(yi)定范圍內隨負(fu)荷(he)而增(zeng)大(da)，從而引起(qi)(qi)更為嚴(yan)重的(de)(de)磨損(sun)，甚至引起(qi)(qi)咬缸（活塞卡在(zai)氣缸內），連桿(gan)斷裂等嚴(yan)重損(sun)壞。堵(du)轉(zhuan)(zhuan)(zhuan)(zhuan)時(shi)(shi)的(de)(de)電(dian)(dian)(dian)(dian)流（堵(du)轉(zhuan)(zhuan)(zhuan)(zhuan)電(dian)(dian)(dian)(dian)流）大(da)約是(shi)正(zheng)(zheng)常(chang)運行電(dian)(dian)(dian)(dian)流的(de)(de)4－8倍。電(dian)(dian)(dian)(dian)機(ji)(ji)啟動(dong)瞬間(jian)，電(dian)(dian)(dian)(dian)流的(de)(de)峰值(zhi)可(ke)接(jie)近或達到堵(du)轉(zhuan)(zhuan)(zhuan)(zhuan)電(dian)(dian)(dian)(dian)流。由(you)于電(dian)(dian)(dian)(dian)阻放熱量與電(dian)(dian)(dian)(dian)流的(de)(de)平(ping)方成(cheng)正(zheng)(zheng)比，啟動(dong)和(he)(he)堵(du)轉(zhuan)(zhuan)(zhuan)(zhuan)時(shi)(shi)的(de)(de)電(dian)(dian)(dian)(dian)流會(hui)(hui)(hui)使繞組(zu)迅(xun)速升(sheng)溫。熱保護(hu)可(ke)以在(zai)堵(du)轉(zhuan)(zhuan)(zhuan)(zhuan)時(shi)(shi)保護(hu)電(dian)(dian)(dian)(dian)極，但(dan)一(yi)般不(bu)會(hui)(hui)(hui)有很(hen)快(kuai)的(de)(de)響(xiang)應(ying)，不(bu)能(neng)阻止頻繁啟動(dong)等引起(qi)(qi)的(de)(de)繞組(zu)溫度變化。頻繁啟動(dong)和(he)(he)異常(chang)負(fu)荷(he)，使繞組(zu)經受高(gao)溫考(kao)驗，會(hui)(hui)(hui)降低漆包(bao)線的(de)(de)絕(jue)緣(yuan)性(xing)能(neng)。此外(wai)，壓(ya)縮氣體所需負(fu)荷(he)也會(hui)(hui)(hui)隨壓(ya)縮比增(zeng)大(da)和(he)(he)壓(ya)差增(zeng)大(da)而增(zeng)大(da)。

因此(ci)將(jiang)高(gao)溫(wen)壓縮(suo)機用于(yu)低(di)溫(wen)，或將(jiang)低(di)溫(wen)壓縮(suo)機用于(yu)高(gao)溫(wen)，都會影響(xiang)電機負荷和散熱，是不合(he)適的(de)，會縮(suo)短電極(ji)使用壽(shou)命。繞組絕緣(yuan)性能變差后，如果有其它因素（如金屬屑構成導電回路，酸性潤滑油等）配合(he)，很容易引起(qi)短路而損(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(duan)路和(he)接地絕(jue)緣(yuan)值低的(de)罪魁禍首。

壓縮機運轉(zhuan)(zhuan)時(shi)(shi)(shi)的(de)正常(chang)振動(dong)(dong)，以(yi)及每次啟動(dong)(dong)時(shi)(shi)(shi)繞(rao)(rao)組(zu)(zu)(zu)受電(dian)(dian)磁(ci)力作(zuo)用而扭動(dong)(dong)，都會(hui)(hui)促使(shi)(shi)夾雜于繞(rao)(rao)組(zu)(zu)(zu)間(jian)的(de)金(jin)屬(shu)(shu)屑與繞(rao)(rao)組(zu)(zu)(zu)漆包線之間(jian)的(de)相(xiang)對(dui)運動(dong)(dong)和(he)摩擦。棱角銳利的(de)金(jin)屬(shu)(shu)屑會(hui)(hui)劃傷(shang)漆包線絕緣層，引起短(duan)路(lu)。金(jin)屬(shu)(shu)屑的(de)來源包括(kuo)施工時(shi)(shi)(shi)留下的(de)銅(tong)管(guan)(guan)屑，焊渣，壓(ya)縮(suo)機(ji)內部磨(mo)損(sun)和(he)零部件損(sun)壞(huai)（比如閥片破碎(sui)(sui)）時(shi)(shi)(shi)掉下的(de)金(jin)屬(shu)(shu)屑等。對(dui)于全(quan)封(feng)(feng)閉(bi)壓(ya)縮(suo)機(ji)（包括(kuo)全(quan)封(feng)(feng)閉(bi)渦(wo)旋壓(ya)縮(suo)機(ji)），這(zhe)些(xie)(xie)金(jin)屬(shu)(shu)屑或(huo)碎(sui)(sui)粒會(hui)(hui)落在繞(rao)(rao)組(zu)(zu)(zu)上。對(dui)于半封(feng)(feng)閉(bi)壓(ya)縮(suo)機(ji)，有(you)(you)些(xie)(xie)顆粒會(hui)(hui)隨氣(qi)體和(he)潤(run)滑油在系統中(zhong)流(liu)動(dong)(dong)，最后(hou)由(you)于磁(ci)性聚集在繞(rao)(rao)組(zu)(zu)(zu)中(zhong)；而有(you)(you)些(xie)(xie)金(jin)屬(shu)(shu)屑（比如軸(zhou)承(cheng)磨(mo)損(sun)以(yi)及電(dian)(dian)機(ji)轉(zhuan)(zhuan)子(zi)與定子(zi)磨(mo)損(sun)（掃膛）時(shi)(shi)(shi)產生(sheng)(sheng)的(de)）會(hui)(hui)直(zhi)接落在繞(rao)(rao)組(zu)(zu)(zu)上。繞(rao)(rao)組(zu)(zu)(zu)中(zhong)聚集了金(jin)屬(shu)(shu)屑后(hou)，發生(sheng)(sheng)短(duan)路(lu)只是一個時(shi)(shi)(shi)間(jian)問題。需(xu)要特別(bie)提請注意的(de)是雙(shuang)級(ji)(ji)(ji)壓(ya)縮(suo)機(ji)。在雙(shuang)級(ji)(ji)(ji)壓(ya)縮(suo)機(ji)中(zhong)，回氣(qi)以(yi)及正常(chang)的(de)回油直(zhi)接進入第一級(ji)(ji)(ji)（低壓(ya)級(ji)(ji)(ji)）氣(qi)缸(gang)，壓(ya)縮(suo)后(hou)經(jing)中(zhong)壓(ya)管(guan)(guan)進入電(dian)(dian)機(ji)腔(qiang)冷卻繞(rao)(rao)組(zu)(zu)(zu)，然后(hou)和(he)普通單級(ji)(ji)(ji)壓(ya)縮(suo)機(ji)一樣，進入第二級(ji)(ji)(ji)（高壓(ya)級(ji)(ji)(ji)氣(qi)缸(gang)）。回氣(qi)中(zhong)帶有(you)(you)潤(run)滑油，已(yi)經(jing)使(shi)(shi)壓(ya)縮(suo)過程(cheng)如履薄冰，如果(guo)再有(you)(you)回液，第一級(ji)(ji)(ji)氣(qi)缸(gang)的(de)閥片很容易被(bei)打碎(sui)(sui)。碎(sui)(sui)閥片經(jing)中(zhong)壓(ya)管(guan)(guan)后(hou)可進入繞(rao)(rao)組(zu)(zu)(zu)。因此(ci)，雙(shuang)級(ji)(ji)(ji)壓(ya)縮(suo)機(ji)比單級(ji)(ji)(ji)壓(ya)縮(suo)機(ji)更容易出現金(jin)屬(shu)(shu)屑引起的(de)電(dian)(dian)機(ji)短(duan)路(lu)。

不幸(xing)的(de)事情往(wang)往(wang)湊到(dao)一(yi)塊，出(chu)問題的(de)壓縮(suo)機在開機分析時聞道的(de)常(chang)常(chang)是潤(run)(run)(run)滑(hua)油(you)的(de)焦(jiao)(jiao)糊味。金屬(shu)面(mian)嚴(yan)重(zhong)磨(mo)損時溫(wen)度是很高的(de)，而潤(run)(run)(run)滑(hua)油(you)在175?C以上時開始焦(jiao)(jiao)化。系統中如果有較多水分（真空(kong)抽得不理想，潤(run)(run)(run)滑(hua)油(you)和(he)制冷劑(ji)含(han)水量大，負(fu)壓回氣管(guan)破裂后空(kong)氣進入(ru)等），潤(run)(run)(run)滑(hua)油(you)就(jiu)可能出(chu)現(xian)酸性(xing)(xing)。酸性(xing)(xing)潤(run)(run)(run)滑(hua)油(you)會腐蝕銅(tong)管(guan)和(he)繞組絕(jue)緣層，一(yi)方面(mian)，它會引起(qi)鍍銅(tong)現(xian)象；另(ling)一(yi)方面(mian)，這(zhe)種含(han)有銅(tong)原子的(de)酸性(xing)(xing)潤(run)(run)(run)滑(hua)油(you)的(de)絕(jue)緣性(xing)(xing)能很差，為(wei)繞組短路(lu)提供(gong)了條(tiao)件。

四、接觸器問題

接觸器(qi)是電機控制回路中重要部件之一，選型不合理可以毀壞最好的壓縮機。

按負載正確(que)選(xuan)擇(ze)接(jie)(jie)觸器是(shi)極其(qi)重要的(de)。接(jie)(jie)觸器必須(xu)能(neng)滿(man)足苛(ke)刻的(de)條件，如(ru)快速循環，持(chi)續超載和低電(dian)壓。它(ta)們必須(xu)有(you)足夠大的(de)面積以(yi)散發負載電(dian)流所產生的(de)熱(re)量，觸點材料(liao)的(de)選(xuan)擇(ze)必須(xu)在(zai)啟動或堵轉等大電(dian)流情況下能(neng)防止焊合。為了安全可靠，壓縮(suo)機接(jie)(jie)觸器要同(tong)時(shi)斷(duan)開(kai)三相(xiang)電(dian)路(lu)。谷(gu)輪(lun)公(gong)司不推薦斷(duan)開(kai)二(er)相(xiang)電(dian)路(lu)的(de)方法。在(zai)美國，谷(gu)輪(lun)公(gong)司認可的(de)接(jie)(jie)觸器必須(xu)滿(man)足如(ru)下四項：

接觸器必(bi)須(xu)滿足ARI標準780-78“專用接觸器標準”規定的工作和測試準則。

制造商必(bi)須(xu)保證接(jie)觸器在室(shi)溫(wen)下，在最低銘牌電壓的80％時能閉合。

當使用單個接(jie)(jie)觸(chu)(chu)(chu)器時，接(jie)(jie)觸(chu)(chu)(chu)器額定電(dian)流必須大于電(dian)機(ji)(ji)銘牌電(dian)流額定值(RLA).同時，接(jie)(jie)觸(chu)(chu)(chu)器必須能承受電(dian)機(ji)(ji)堵轉電(dian)流。如(ru)果接(jie)(jie)觸(chu)(chu)(chu)器下游還(huan)有其它負載，比如(ru)電(dian)機(ji)(ji)風扇等，也必須考慮。

當(dang)使(shi)用兩個(ge)接觸器(qi)時，每個(ge)接觸器(qi)的分繞(rao)組堵(du)(du)轉額(e)定(ding)值(zhi)必須等于或大于壓縮機半繞(rao)組堵(du)(du)轉額(e)定(ding)值(zhi)。

接觸(chu)器的額定電流不能低于壓縮機銘牌上(shang)的額定電流。

規格小或質量低(di)劣的(de)(de)(de)接(jie)(jie)(jie)觸器無法經受(shou)壓縮(suo)機(ji)啟(qi)(qi)動(dong)，堵轉(zhuan)和(he)低(di)電(dian)壓時的(de)(de)(de)大(da)電(dian)流沖擊，容易(yi)出現(xian)單(dan)相或多相觸點抖(dou)動(dong),焊接(jie)(jie)(jie)甚至脫落的(de)(de)(de)現(xian)象，引(yin)起(qi)電(dian)機(ji)損壞。觸點抖(dou)動(dong)的(de)(de)(de)接(jie)(jie)(jie)觸器頻繁地啟(qi)(qi)停電(dian)機(ji)。電(dian)機(ji)頻繁啟(qi)(qi)動(dong)，巨大(da)的(de)(de)(de)啟(qi)(qi)動(dong)電(dian)流和(he)發熱,會加劇繞(rao)組絕(jue)(jue)緣層的(de)(de)(de)老化。每(mei)次啟(qi)(qi)動(dong)時，磁性力(li)矩使電(dian)機(ji)繞(rao)組有(you)微小的(de)(de)(de)移動(dong)和(he)相互摩擦。如(ru)(ru)果有(you)其(qi)它因(yin)素配合（如(ru)(ru)金屬屑，絕(jue)(jue)緣性差的(de)(de)(de)潤滑油等(deng)），很容易(yi)引(yin)起(qi)繞(rao)組間(jian)短路。熱保護系統并(bing)未(wei)設(she)計(ji)成能防止這種毀壞。此外，抖(dou)動(dong)的(de)(de)(de)接(jie)(jie)(jie)觸器線圈容易(yi)失效。如(ru)(ru)果有(you)接(jie)(jie)(jie)觸線圈損壞，容易(yi)出現(xian)單(dan)相狀(zhuang)態(tai)。

如果接觸(chu)(chu)器(qi)選型偏小(xiao)，觸(chu)(chu)頭(tou)不能承受(shou)電弧和由于頻繁開(kai)停循(xun)環或(huo)不穩定控(kong)制(zhi)(zhi)回路電壓產生的高(gao)溫，可能焊(han)合或(huo)從觸(chu)(chu)頭(tou)架中(zhong)脫(tuo)落。焊(han)合的觸(chu)(chu)頭(tou)將(jiang)產生永久性單(dan)相(xiang)狀(zhuang)態(tai)，使過載保護器(qi)持續地循(xun)環接通(tong)和斷開(kai)，需要特別強調(diao)的是，接觸(chu)(chu)器(qi)觸(chu)(chu)點(dian)焊(han)合后(hou)，依(yi)賴接觸(chu)(chu)器(qi)斷開(kai)壓縮機電源回路的所(suo)有控(kong)制(zhi)(zhi)（比如高(gao)低壓控(kong)制(zhi)(zhi)，油壓控(kong)制(zhi)(zhi)，融霜控(kong)制(zhi)(zhi)等）將(jiang)全部失效，壓縮機處(chu)于無保護狀(zhuang)態(tai)。

因此，當電機(ji)燒毀后(hou)，檢查接觸器(qi)(qi)是必不可少的工序。接觸器(qi)(qi)是導致電機(ji)損壞(huai)的一個常常被人遺忘的重要原因。

五、電源缺相和電壓異常

電壓不正常和缺相可以輕而易(yi)舉地毀掉(diao)任(ren)何電機(ji)。

電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)變化(hua)范圍不(bu)(bu)(bu)(bu)能(neng)超過(guo)額定(ding)(ding)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)的(de)(de)(de)(de)±10%。三相(xiang)(xiang)(xiang)(xiang)間的(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)不(bu)(bu)(bu)(bu)平(ping)(ping)衡(heng)(heng)(heng)(heng)不(bu)(bu)(bu)(bu)能(neng)超過(guo)5％。大(da)功率(lv)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)(ji)必(bi)(bi)須(xu)獨(du)立(li)供電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)，以防(fang)(fang)同線其他(ta)大(da)功率(lv)設備啟動(dong)(dong)和運(yun)轉(zhuan)(zhuan)時(shi)造成低電(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)機(ji)(ji)(ji)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源線必(bi)(bi)須(xu)能(neng)夠承(cheng)載電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)(ji)的(de)(de)(de)(de)額定(ding)(ding)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)。如果(guo)發生缺相(xiang)(xiang)(xiang)(xiang)時(shi)壓(ya)(ya)(ya)(ya)(ya)縮機(ji)(ji)(ji)正(zheng)在(zai)運(yun)轉(zhuan)(zhuan)，它(ta)將繼續運(yun)行但會(hui)(hui)有(you)大(da)的(de)(de)(de)(de)負載電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)。電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)(ji)繞(rao)(rao)組(zu)會(hui)(hui)很快(kuai)過(guo)熱(re)，正(zheng)常情況下壓(ya)(ya)(ya)(ya)(ya)縮機(ji)(ji)(ji)會(hui)(hui)被熱(re)保護(hu)。當電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)(ji)繞(rao)(rao)組(zu)冷卻至設定(ding)(ding)溫(wen)度，接(jie)(jie)觸器(qi)會(hui)(hui)閉合，但壓(ya)(ya)(ya)(ya)(ya)縮機(ji)(ji)(ji)啟動(dong)(dong)不(bu)(bu)(bu)(bu)起來(lai)，出(chu)現堵(du)(du)轉(zhuan)(zhuan)，并進(jin)入“堵(du)(du)轉(zhuan)(zhuan)－熱(re)保護(hu)－堵(du)(du)轉(zhuan)(zhuan)”死循環。現代(dai)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)(ji)繞(rao)(rao)組(zu)的(de)(de)(de)(de)差別非常小，電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源三相(xiang)(xiang)(xiang)(xiang)平(ping)(ping)衡(heng)(heng)(heng)(heng)時(shi)相(xiang)(xiang)(xiang)(xiang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)的(de)(de)(de)(de)差別可以忽略。理想狀態下，相(xiang)(xiang)(xiang)(xiang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)始終相(xiang)(xiang)(xiang)(xiang)等，只要在(zai)任一相(xiang)(xiang)(xiang)(xiang)上接(jie)(jie)一個保護(hu)器(qi)就(jiu)可以防(fang)(fang)止(zhi)過(guo)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)造成的(de)(de)(de)(de)損壞。實際上很難保證(zheng)相(xiang)(xiang)(xiang)(xiang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)的(de)(de)(de)(de)平(ping)(ping)衡(heng)(heng)(heng)(heng)。電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)不(bu)(bu)(bu)(bu)平(ping)(ping)衡(heng)(heng)(heng)(heng)百(bai)(bai)(bai)分(fen)(fen)數計算方法為，相(xiang)(xiang)(xiang)(xiang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)與三相(xiang)(xiang)(xiang)(xiang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)平(ping)(ping)均值(zhi)的(de)(de)(de)(de)最(zui)大(da)偏(pian)差值(zhi)與三相(xiang)(xiang)(xiang)(xiang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)平(ping)(ping)均值(zhi)比值(zhi)。例如，標(biao)稱380V三相(xiang)(xiang)(xiang)(xiang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源，在(zai)壓(ya)(ya)(ya)(ya)(ya)縮機(ji)(ji)(ji)接(jie)(jie)線端測量的(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)分(fen)(fen)別為380V、366V、400V。可以計算出(chu)三相(xiang)(xiang)(xiang)(xiang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)平(ping)(ping)均值(zhi)382V，最(zui)大(da)偏(pian)差為20V,所以電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)不(bu)(bu)(bu)(bu)平(ping)(ping)衡(heng)(heng)(heng)(heng)百(bai)(bai)(bai)分(fen)(fen)數為5.2％。作為電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)不(bu)(bu)(bu)(bu)平(ping)(ping)衡(heng)(heng)(heng)(heng)的(de)(de)(de)(de)結(jie)果(guo)，在(zai)正(zheng)常運(yun)行使負載電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)的(de)(de)(de)(de)不(bu)(bu)(bu)(bu)平(ping)(ping)衡(heng)(heng)(heng)(heng)是電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)不(bu)(bu)(bu)(bu)平(ping)(ping)衡(heng)(heng)(heng)(heng)百(bai)(bai)(bai)分(fen)(fen)點數的(de)(de)(de)(de)4－10倍(bei)。前(qian)例中，5.2％不(bu)(bu)(bu)(bu)平(ping)(ping)衡(heng)(heng)(heng)(heng)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)可能(neng)引起50％的(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)不(bu)(bu)(bu)(bu)平(ping)(ping)衡(heng)(heng)(heng)(heng)。美國(guo)國(guo)家電(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)動(dong)(dong)機(ji)(ji)(ji)和發電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)機(ji)(ji)(ji)標(biao)準(zhun)出(chu)版物指出(chu)，由不(bu)(bu)(bu)(bu)平(ping)(ping)衡(heng)(heng)(heng)(heng)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)造成的(de)(de)(de)(de)相(xiang)(xiang)(xiang)(xiang)繞(rao)(rao)組(zu)溫(wen)升百(bai)(bai)(bai)分(fen)(fen)比大(da)約是電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)不(bu)(bu)(bu)(bu)平(ping)(ping)衡(heng)(heng)(heng)(heng)百(bai)(bai)(bai)分(fen)(fen)點數平(ping)(ping)方的(de)(de)(de)(de)兩(liang)倍(bei)。前(qian)例中電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)不(bu)(bu)(bu)(bu)平(ping)(ping)衡(heng)(heng)(heng)(heng)點數為5.2，繞(rao)(rao)組(zu)溫(wen)度增(zeng)加的(de)(de)(de)(de)百(bai)(bai)(bai)分(fen)(fen)數為54％。結(jie)果(guo)是一相(xiang)(xiang)(xiang)(xiang)繞(rao)(rao)組(zu)過(guo)熱(re)而其他(ta)兩(liang)個繞(rao)(rao)組(zu)溫(wen)度正(zheng)常。一份由U.L.(保險(xian)商(shang)實驗(yan)室，美國(guo))完成的(de)(de)(de)(de)調查顯示(shi)，43％的(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)力公司允(yun)許3％的(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)不(bu)(bu)(bu)(bu)平(ping)(ping)衡(heng)(heng)(heng)(heng)，另有(you)30％的(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)力公司允(yun)許5％的(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)(ya)(ya)(ya)不(bu)(bu)(bu)(bu)平(ping)(ping)衡(heng)(heng)(heng)(heng)。

六、冷卻不足

功率較大的(de)壓縮機(ji)一般(ban)都是(shi)回(hui)氣冷卻型的(de)。蒸發(fa)溫度越低，系統質量流(liu)往往越小。

當蒸發(fa)溫(wen)度(du)(du)很低時(shi)（超(chao)過(guo)制造(zao)商的(de)規定），流量(liang)(liang)就(jiu)不(bu)足以冷(leng)(leng)卻(que)電(dian)(dian)機(ji)(ji)(ji)(ji)(ji)(ji)，電(dian)(dian)機(ji)(ji)(ji)(ji)(ji)(ji)就(jiu)會(hui)在較高溫(wen)度(du)(du)下運轉。空氣冷(leng)(leng)卻(que)型(xing)壓縮(suo)(suo)(suo)機(ji)(ji)(ji)(ji)(ji)(ji)（一(yi)般不(bu)超(chao)過(guo)10HP）對回(hui)氣的(de)依賴性(xing)小，但對壓縮(suo)(suo)(suo)機(ji)(ji)(ji)(ji)(ji)(ji)環(huan)境溫(wen)度(du)(du)和冷(leng)(leng)卻(que)風量(liang)(liang)有(you)明確要(yao)求。制冷(leng)(leng)劑(ji)(ji)大量(liang)(liang)泄(xie)漏(lou)也(ye)會(hui)造(zao)成系統質(zhi)量(liang)(liang)流減小，電(dian)(dian)機(ji)(ji)(ji)(ji)(ji)(ji)的(de)冷(leng)(leng)卻(que)也(ye)會(hui)受到(dao)影響。一(yi)些(xie)無人看(kan)管的(de)冷(leng)(leng)庫，往(wang)(wang)往(wang)(wang)要(yao)等到(dao)制冷(leng)(leng)效(xiao)果很差時(shi)才會(hui)發(fa)現制冷(leng)(leng)劑(ji)(ji)大量(liang)(liang)泄(xie)漏(lou)了。電(dian)(dian)機(ji)(ji)(ji)(ji)(ji)(ji)過(guo)熱后(hou)會(hui)出現頻繁保(bao)護(hu)，有(you)些(xie)用戶(hu)不(bu)深入檢查原因，甚至將熱保(bao)護(hu)器短(duan)路，那是(shi)非(fei)常(chang)糟(zao)糕的(de)事情(qing)。過(guo)不(bu)了多(duo)久，電(dian)(dian)機(ji)(ji)(ji)(ji)(ji)(ji)就(jiu)會(hui)燒掉。壓縮(suo)(suo)(suo)機(ji)(ji)(ji)(ji)(ji)(ji)都有(you)安全運行(xing)工況(kuang)范圍(wei)。安全工況(kuang)主要(yao)的(de)考慮因素就(jiu)是(shi)壓縮(suo)(suo)(suo)機(ji)(ji)(ji)(ji)(ji)(ji)和電(dian)(dian)機(ji)(ji)(ji)(ji)(ji)(ji)的(de)負荷與冷(leng)(leng)卻(que)。由于不(bu)同溫(wen)區的(de)壓縮(suo)(suo)(suo)機(ji)(ji)(ji)(ji)(ji)(ji)的(de)價(jia)格不(bu)同，過(guo)去國內冷(leng)(leng)凍(dong)行(xing)業超(chao)范圍(wei)使(shi)用壓縮(suo)(suo)(suo)機(ji)(ji)(ji)(ji)(ji)(ji)是(shi)比較常(chang)見(jian)的(de)。隨(sui)著專業知(zhi)識的(de)增長和經濟條件的(de)改(gai)善，情(qing)況(kuang)已明顯改(gai)善。