380伏(fu)(fu)三相(xiang)(xiang)(xiang)四線(xian)電(dian)(dian)路中,任意(yi)(yi)兩根火線(xian)之(zhi)間的電(dian)(dian)壓都是380伏(fu)(fu),任意(yi)(yi)一根火線(xian)與零線(xian)之(zhi)間都可以組成220伏(fu)(fu)。這個系統可以形(xing)成三種(zhong)電(dian)(dian)源:即單(dan)相(xiang)(xiang)(xiang)220伏(fu)(fu)電(dian)(dian)源,單(dan)相(xiang)(xiang)(xiang)380伏(fu)(fu)電(dian)(dian)源,三相(xiang)(xiang)(xiang)380伏(fu)(fu)電(dian)(dian)源,第(di) I 種(zhong)家用(yong)(yong)比較(jiao)多,第(di)三種(zhong)工(gong)廠里電(dian)(dian)機類用(yong)(yong)得(de)多,第(di)二種(zhong)用(yong)(yong)得(de)少(shao),只有交流電(dian)(dian)焊機經常用(yong)(yong)到單(dan)相(xiang)(xiang)(xiang)380伏(fu)(fu)電(dian)(dian)源。