三相電加熱管

        380伏(fu)(fu)三(san)相(xiang)(xiang)四(si)線(xian)(xian)電(dian)(dian)(dian)(dian)路(lu)中，任意兩根火線(xian)(xian)之(zhi)間的電(dian)(dian)(dian)(dian)壓都(dou)是380伏(fu)(fu)，任意一根火線(xian)(xian)與零(ling)線(xian)(xian)之(zhi)間都(dou)可(ke)以組成220伏(fu)(fu)。這個系(xi)統可(ke)以形成三(san)種(zhong)電(dian)(dian)(dian)(dian)源(yuan)：即單相(xiang)(xiang)220伏(fu)(fu)電(dian)(dian)(dian)(dian)源(yuan)，單相(xiang)(xiang)380伏(fu)(fu)電(dian)(dian)(dian)(dian)源(yuan)，三(san)相(xiang)(xiang)380伏(fu)(fu)電(dian)(dian)(dian)(dian)源(yuan)，第 I 種(zhong)家(jia)用(yong)比較多，第三(san)種(zhong)工廠里電(dian)(dian)(dian)(dian)機類用(yong)得(de)多，第二種(zhong)用(yong)得(de)少，只有交流電(dian)(dian)(dian)(dian)焊機經常用(yong)到單相(xiang)(xiang)380伏(fu)(fu)電(dian)(dian)(dian)(dian)源(yuan)。