三相電加熱管

        380伏三(san)(san)相(xiang)四(si)線(xian)電(dian)(dian)路中，任(ren)意兩根(gen)火線(xian)之(zhi)間的電(dian)(dian)壓(ya)都是380伏，任(ren)意一根(gen)火線(xian)與(yu)零線(xian)之(zhi)間都可以組成(cheng)220伏。這個系統可以形(xing)成(cheng)三(san)(san)種電(dian)(dian)源：即單相(xiang)220伏電(dian)(dian)源，單相(xiang)380伏電(dian)(dian)源，三(san)(san)相(xiang)380伏電(dian)(dian)源，第(di) I 種家(jia)用(yong)比較多，第(di)三(san)(san)種工廠(chang)里電(dian)(dian)機類用(yong)得多，第(di)二種用(yong)得少，只有(you)交(jiao)流電(dian)(dian)焊(han)機經常用(yong)到單相(xiang)380伏電(dian)(dian)源。