380伏(fu)(fu)三(san)(san)相四線電(dian)(dian)路中,任(ren)意兩根(gen)火線之(zhi)間的電(dian)(dian)壓(ya)都是380伏(fu)(fu),任(ren)意一根(gen)火線與零(ling)線之(zhi)間都可以(yi)組(zu)成(cheng)220伏(fu)(fu)。這(zhe)個系統(tong)可以(yi)形成(cheng)三(san)(san)種電(dian)(dian)源(yuan):即單相220伏(fu)(fu)電(dian)(dian)源(yuan),單相380伏(fu)(fu)電(dian)(dian)源(yuan),三(san)(san)相380伏(fu)(fu)電(dian)(dian)源(yuan),第 I 種家(jia)用(yong)比較多,第三(san)(san)種工廠里電(dian)(dian)機類(lei)用(yong)得(de)多,第二(er)種用(yong)得(de)少,只有交流電(dian)(dian)焊機經常用(yong)到單相380伏(fu)(fu)電(dian)(dian)源(yuan)。