三相電加熱管

        380伏三(san)(san)相(xiang)(xiang)四(si)線電(dian)(dian)路中(zhong)，任意兩根(gen)火線之(zhi)間(jian)的電(dian)(dian)壓(ya)都是(shi)380伏，任意一根(gen)火線與零(ling)線之(zhi)間(jian)都可以組(zu)成(cheng)220伏。這個系統可以形成(cheng)三(san)(san)種(zhong)電(dian)(dian)源(yuan)：即(ji)單(dan)相(xiang)(xiang)220伏電(dian)(dian)源(yuan)，單(dan)相(xiang)(xiang)380伏電(dian)(dian)源(yuan)，三(san)(san)相(xiang)(xiang)380伏電(dian)(dian)源(yuan)，第 I 種(zhong)家用(yong)(yong)比較多，第三(san)(san)種(zhong)工廠里電(dian)(dian)機(ji)類用(yong)(yong)得(de)多，第二種(zhong)用(yong)(yong)得(de)少，只(zhi)有交流(liu)電(dian)(dian)焊(han)機(ji)經常(chang)用(yong)(yong)到單(dan)相(xiang)(xiang)380伏電(dian)(dian)源(yuan)。