380伏(fu)三(san)相(xiang)四線(xian)電(dian)(dian)路中(zhong),任意(yi)兩根火線(xian)之間的電(dian)(dian)壓都(dou)是380伏(fu),任意(yi)一根火線(xian)與零線(xian)之間都(dou)可以組成220伏(fu)。這(zhe)個系統可以形成三(san)種(zhong)(zhong)電(dian)(dian)源(yuan):即單相(xiang)220伏(fu)電(dian)(dian)源(yuan),單相(xiang)380伏(fu)電(dian)(dian)源(yuan),三(san)相(xiang)380伏(fu)電(dian)(dian)源(yuan),第(di) I 種(zhong)(zhong)家用比較多,第(di)三(san)種(zhong)(zhong)工廠里(li)電(dian)(dian)機(ji)類(lei)用得(de)多,第(di)二種(zhong)(zhong)用得(de)少,只有(you)交流電(dian)(dian)焊(han)機(ji)經常用到單相(xiang)380伏(fu)電(dian)(dian)源(yuan)。