380伏(fu)三(san)相四線電(dian)(dian)路中,任意兩(liang)根(gen)火線之(zhi)(zhi)間(jian)的電(dian)(dian)壓都是380伏(fu),任意一根(gen)火線與零線之(zhi)(zhi)間(jian)都可(ke)以組成(cheng)220伏(fu)。這個系統可(ke)以形成(cheng)三(san)種(zhong)電(dian)(dian)源(yuan):即單(dan)相220伏(fu)電(dian)(dian)源(yuan),單(dan)相380伏(fu)電(dian)(dian)源(yuan),三(san)相380伏(fu)電(dian)(dian)源(yuan),第(di) I 種(zhong)家(jia)用比較多(duo),第(di)三(san)種(zhong)工廠里電(dian)(dian)機(ji)類用得多(duo),第(di)二種(zhong)用得少,只(zhi)有交流(liu)電(dian)(dian)焊(han)機(ji)經常用到(dao)單(dan)相380伏(fu)電(dian)(dian)源(yuan)。