三相電加熱管

        380伏(fu)三(san)相四(si)線(xian)(xian)電(dian)(dian)(dian)(dian)路中，任意兩根火線(xian)(xian)之(zhi)(zhi)間的(de)電(dian)(dian)(dian)(dian)壓都是(shi)380伏(fu)，任意一(yi)根火線(xian)(xian)與零線(xian)(xian)之(zhi)(zhi)間都可(ke)以(yi)組成220伏(fu)。這個系(xi)統可(ke)以(yi)形成三(san)種(zhong)(zhong)電(dian)(dian)(dian)(dian)源：即單相220伏(fu)電(dian)(dian)(dian)(dian)源，單相380伏(fu)電(dian)(dian)(dian)(dian)源，三(san)相380伏(fu)電(dian)(dian)(dian)(dian)源，第(di) I 種(zhong)(zhong)家(jia)用(yong)(yong)比較多，第(di)三(san)種(zhong)(zhong)工廠(chang)里(li)電(dian)(dian)(dian)(dian)機(ji)類用(yong)(yong)得(de)多，第(di)二種(zhong)(zhong)用(yong)(yong)得(de)少，只有(you)交流電(dian)(dian)(dian)(dian)焊機(ji)經常用(yong)(yong)到(dao)單相380伏(fu)電(dian)(dian)(dian)(dian)源。