三相電加熱管

        380伏三(san)相(xiang)(xiang)(xiang)四線(xian)電(dian)(dian)(dian)路中，任意兩根火線(xian)之(zhi)間(jian)的電(dian)(dian)(dian)壓都(dou)是380伏，任意一根火線(xian)與零線(xian)之(zhi)間(jian)都(dou)可以(yi)組成220伏。這個系統(tong)可以(yi)形成三(san)種電(dian)(dian)(dian)源(yuan)(yuan)：即(ji)單(dan)相(xiang)(xiang)(xiang)220伏電(dian)(dian)(dian)源(yuan)(yuan)，單(dan)相(xiang)(xiang)(xiang)380伏電(dian)(dian)(dian)源(yuan)(yuan)，三(san)相(xiang)(xiang)(xiang)380伏電(dian)(dian)(dian)源(yuan)(yuan)，第(di) I 種家(jia)用比較多，第(di)三(san)種工廠(chang)里(li)電(dian)(dian)(dian)機類用得多，第(di)二種用得少，只有(you)交流電(dian)(dian)(dian)焊機經(jing)常用到單(dan)相(xiang)(xiang)(xiang)380伏電(dian)(dian)(dian)源(yuan)(yuan)。