電機(ji)(ji)的三相(xiang)電源平衡(heng)時，電動機(ji)(ji)的三相(xiang)空載電流中(zhong)任何一相(xiang)與三相(xiang)平均(jun)值(zhi)的偏差(cha)應(ying)不大(da)于(yu)三相(xiang)平均(jun)值(zhi)的10%。

用(yong)(yong)戶所提出的(de)(de)(de)(de)三(san)相(xiang)電(dian)(dian)(dian)(dian)流不平衡(heng)問(wen)題(ti)(ti)，絕(jue)大部分是(shi)電(dian)(dian)(dian)(dian)機(ji)(ji)(ji)以(yi)外用(yong)(yong)戶電(dian)(dian)(dian)(dian)源(yuan)方(fang)面的(de)(de)(de)(de)問(wen)題(ti)(ti)（包括本身(shen)電(dian)(dian)(dian)(dian)壓不平衡(heng)和電(dian)(dian)(dian)(dian)盤(pan)接(jie)線接(jie)觸不良所造成(cheng)），具(ju)體檢測的(de)(de)(de)(de)方(fang)法是(shi)把三(san)相(xiang)電(dian)(dian)(dian)(dian)源(yuan)倒相(xiang)看(kan)一(yi)下，（注意一(yi)定(ding)要在電(dian)(dian)(dian)(dian)機(ji)(ji)(ji)出線盒接(jie)線部位(wei)倒，這(zhe)樣可(ke)以(yi)清楚的(de)(de)(de)(de)判斷(duan)出電(dian)(dian)(dian)(dian)機(ji)(ji)(ji)以(yi)外部分的(de)(de)(de)(de)故(gu)障），即(ji)假(jia)設當時三(san)相(xiang)電(dian)(dian)(dian)(dian)源(yuan)接(jie)線順序為(wei)U、V、W，現(xian)在重(zhong)新改接(jie)成(cheng)W、U、V，這(zhe)樣仍然(ran)能夠保(bao)證電(dian)(dian)(dian)(dian)機(ji)(ji)(ji)原來(lai)(lai)的(de)(de)(de)(de)轉(zhuan)向，如原先三(san)相(xiang)電(dian)(dian)(dian)(dian)流最高或最低的(de)(de)(de)(de)一(yi)相(xiang)在倒線的(de)(de)(de)(de)過(guo)程(cheng)當中(zhong)隨(sui)之(zhi)線的(de)(de)(de)(de)改變而改變，則(ze)說明電(dian)(dian)(dian)(dian)源(yuan)有(you)問(wen)題(ti)(ti)，電(dian)(dian)(dian)(dian)機(ji)(ji)(ji)本身(shen)沒有(you)問(wen)題(ti)(ti)，如最高或最低一(yi)相(xiang)固定(ding)在原先一(yi)相(xiang)不動，則(ze)說明電(dian)(dian)(dian)(dian)機(ji)(ji)(ji)可(ke)能有(you)問(wen)題(ti)(ti)。但有(you)時用(yong)(yong)戶采用(yong)(yong)的(de)(de)(de)(de)是(shi)星角接(jie)轉(zhuan)換起動，從電(dian)(dian)(dian)(dian)機(ji)(ji)(ji)接(jie)出來(lai)(lai)的(de)(de)(de)(de)是(shi)六根(gen)(gen)線，則(ze)用(yong)(yong)同樣的(de)(de)(de)(de)方(fang)法先倒上面三(san)根(gen)(gen)，如不行，再倒下面的(de)(de)(de)(de)三(san)根(gen)(gen)線。