三相電加熱管

        380伏三(san)相(xiang)(xiang)四線(xian)電(dian)(dian)(dian)路中(zhong)，任(ren)意兩根火線(xian)之間的電(dian)(dian)(dian)壓都是380伏，任(ren)意一(yi)根火線(xian)與零線(xian)之間都可以組成220伏。這個系統(tong)可以形成三(san)種電(dian)(dian)(dian)源：即單相(xiang)(xiang)220伏電(dian)(dian)(dian)源，單相(xiang)(xiang)380伏電(dian)(dian)(dian)源，三(san)相(xiang)(xiang)380伏電(dian)(dian)(dian)源，第(di) I 種家用比較多(duo)，第(di)三(san)種工廠(chang)里電(dian)(dian)(dian)機(ji)類用得多(duo)，第(di)二(er)種用得少，只有交流(liu)電(dian)(dian)(dian)焊機(ji)經常用到單相(xiang)(xiang)380伏電(dian)(dian)(dian)源。