380伏(fu)三相(xiang)(xiang)(xiang)四(si)線(xian)電(dian)路中(zhong),任意兩根火(huo)線(xian)之間(jian)(jian)的電(dian)壓都(dou)是380伏(fu),任意一根火(huo)線(xian)與(yu)零線(xian)之間(jian)(jian)都(dou)可以組成220伏(fu)。這個系統(tong)可以形(xing)成三種(zhong)電(dian)源(yuan):即單相(xiang)(xiang)(xiang)220伏(fu)電(dian)源(yuan),單相(xiang)(xiang)(xiang)380伏(fu)電(dian)源(yuan),三相(xiang)(xiang)(xiang)380伏(fu)電(dian)源(yuan),第(di) I 種(zhong)家(jia)用比較(jiao)多,第(di)三種(zhong)工廠里電(dian)機類用得(de)多,第(di)二種(zhong)用得(de)少,只有交流(liu)電(dian)焊機經常(chang)用到單相(xiang)(xiang)(xiang)380伏(fu)電(dian)源(yuan)。