380伏(fu)(fu)三(san)相四(si)線電(dian)(dian)(dian)(dian)路(lu)中,任意兩根火線之(zhi)間(jian)的電(dian)(dian)(dian)(dian)壓都是380伏(fu)(fu),任意一根火線與零線之(zhi)間(jian)都可以組成(cheng)220伏(fu)(fu)。這(zhe)個系統(tong)可以形成(cheng)三(san)種電(dian)(dian)(dian)(dian)源:即單(dan)(dan)相220伏(fu)(fu)電(dian)(dian)(dian)(dian)源,單(dan)(dan)相380伏(fu)(fu)電(dian)(dian)(dian)(dian)源,三(san)相380伏(fu)(fu)電(dian)(dian)(dian)(dian)源,第 I 種家(jia)用(yong)比較多,第三(san)種工廠里電(dian)(dian)(dian)(dian)機類用(yong)得(de)多,第二(er)種用(yong)得(de)少,只有交流電(dian)(dian)(dian)(dian)焊機經常用(yong)到(dao)單(dan)(dan)相380伏(fu)(fu)電(dian)(dian)(dian)(dian)源。