380伏三(san)(san)相四線電(dian)(dian)(dian)路中,任(ren)(ren)意(yi)兩根火線之間的電(dian)(dian)(dian)壓都(dou)是380伏,任(ren)(ren)意(yi)一根火線與零線之間都(dou)可以(yi)組(zu)成220伏。這個系統可以(yi)形成三(san)(san)種(zhong)(zhong)(zhong)電(dian)(dian)(dian)源(yuan)(yuan)(yuan):即單(dan)相220伏電(dian)(dian)(dian)源(yuan)(yuan)(yuan),單(dan)相380伏電(dian)(dian)(dian)源(yuan)(yuan)(yuan),三(san)(san)相380伏電(dian)(dian)(dian)源(yuan)(yuan)(yuan),第 I 種(zhong)(zhong)(zhong)家用比較多(duo),第三(san)(san)種(zhong)(zhong)(zhong)工廠里電(dian)(dian)(dian)機類用得(de)多(duo),第二種(zhong)(zhong)(zhong)用得(de)少,只有(you)交流電(dian)(dian)(dian)焊機經常用到單(dan)相380伏電(dian)(dian)(dian)源(yuan)(yuan)(yuan)。