380伏(fu)(fu)(fu)三(san)相四線電(dian)(dian)路中,任意兩(liang)根火(huo)線之(zhi)間(jian)(jian)的(de)電(dian)(dian)壓(ya)都(dou)是380伏(fu)(fu)(fu),任意一根火(huo)線與零線之(zhi)間(jian)(jian)都(dou)可以(yi)組成220伏(fu)(fu)(fu)。這個系統可以(yi)形(xing)成三(san)種(zhong)(zhong)電(dian)(dian)源:即(ji)單相220伏(fu)(fu)(fu)電(dian)(dian)源,單相380伏(fu)(fu)(fu)電(dian)(dian)源,三(san)相380伏(fu)(fu)(fu)電(dian)(dian)源,第(di) I 種(zhong)(zhong)家用比較多(duo),第(di)三(san)種(zhong)(zhong)工廠里電(dian)(dian)機(ji)類(lei)用得多(duo),第(di)二種(zhong)(zhong)用得少,只有交流(liu)電(dian)(dian)焊機(ji)經常用到單相380伏(fu)(fu)(fu)電(dian)(dian)源。