三相電加熱管

        380伏三相(xiang)(xiang)四(si)線(xian)電(dian)(dian)路中，任意兩(liang)根火線(xian)之間的電(dian)(dian)壓都是380伏，任意一根火線(xian)與零線(xian)之間都可以組成(cheng)220伏。這個系統可以形成(cheng)三種電(dian)(dian)源：即單相(xiang)(xiang)220伏電(dian)(dian)源，單相(xiang)(xiang)380伏電(dian)(dian)源，三相(xiang)(xiang)380伏電(dian)(dian)源，第 I 種家用(yong)比較多，第三種工廠里電(dian)(dian)機類(lei)用(yong)得多，第二種用(yong)得少，只有交流電(dian)(dian)焊(han)機經(jing)常用(yong)到單相(xiang)(xiang)380伏電(dian)(dian)源。