三相電加熱管

        380伏(fu)(fu)(fu)三相(xiang)四線電(dian)(dian)(dian)(dian)路中，任(ren)意兩(liang)根火線之(zhi)間(jian)的電(dian)(dian)(dian)(dian)壓都(dou)是380伏(fu)(fu)(fu)，任(ren)意一根火線與零線之(zhi)間(jian)都(dou)可(ke)以(yi)組成220伏(fu)(fu)(fu)。這個系統可(ke)以(yi)形成三種電(dian)(dian)(dian)(dian)源(yuan)：即單相(xiang)220伏(fu)(fu)(fu)電(dian)(dian)(dian)(dian)源(yuan)，單相(xiang)380伏(fu)(fu)(fu)電(dian)(dian)(dian)(dian)源(yuan)，三相(xiang)380伏(fu)(fu)(fu)電(dian)(dian)(dian)(dian)源(yuan)，第 I 種家用(yong)比較多，第三種工廠(chang)里電(dian)(dian)(dian)(dian)機類用(yong)得多，第二種用(yong)得少(shao)，只(zhi)有交流電(dian)(dian)(dian)(dian)焊機經常用(yong)到單相(xiang)380伏(fu)(fu)(fu)電(dian)(dian)(dian)(dian)源(yuan)。