三相電加熱管

        380伏(fu)三(san)(san)相(xiang)四(si)線電(dian)(dian)(dian)(dian)路中，任意兩根火(huo)(huo)線之間的電(dian)(dian)(dian)(dian)壓都(dou)是380伏(fu)，任意一根火(huo)(huo)線與零線之間都(dou)可(ke)以組成220伏(fu)。這個系統可(ke)以形成三(san)(san)種電(dian)(dian)(dian)(dian)源(yuan)：即單相(xiang)220伏(fu)電(dian)(dian)(dian)(dian)源(yuan)，單相(xiang)380伏(fu)電(dian)(dian)(dian)(dian)源(yuan)，三(san)(san)相(xiang)380伏(fu)電(dian)(dian)(dian)(dian)源(yuan)，第 I 種家用比較多，第三(san)(san)種工廠里電(dian)(dian)(dian)(dian)機類用得多，第二種用得少(shao)，只有交(jiao)流電(dian)(dian)(dian)(dian)焊機經常用到單相(xiang)380伏(fu)電(dian)(dian)(dian)(dian)源(yuan)。