三相電加熱管

        380伏(fu)(fu)三(san)相(xiang)四線電(dian)(dian)路中，任意兩根火線之間的電(dian)(dian)壓都(dou)是380伏(fu)(fu)，任意一根火線與零(ling)線之間都(dou)可以組(zu)成(cheng)220伏(fu)(fu)。這個系(xi)統可以形(xing)成(cheng)三(san)種(zhong)(zhong)電(dian)(dian)源：即單相(xiang)220伏(fu)(fu)電(dian)(dian)源，單相(xiang)380伏(fu)(fu)電(dian)(dian)源，三(san)相(xiang)380伏(fu)(fu)電(dian)(dian)源，第(di) I 種(zhong)(zhong)家(jia)用(yong)(yong)比較多(duo)，第(di)三(san)種(zhong)(zhong)工廠(chang)里(li)電(dian)(dian)機(ji)類用(yong)(yong)得(de)多(duo)，第(di)二種(zhong)(zhong)用(yong)(yong)得(de)少(shao)，只(zhi)有交流(liu)電(dian)(dian)焊機(ji)經常用(yong)(yong)到單相(xiang)380伏(fu)(fu)電(dian)(dian)源。