三相電加熱管

        380伏三相(xiang)(xiang)四(si)線(xian)(xian)電(dian)(dian)(dian)路(lu)中，任意兩(liang)根火線(xian)(xian)之間的電(dian)(dian)(dian)壓(ya)都(dou)是380伏，任意一(yi)根火線(xian)(xian)與零(ling)線(xian)(xian)之間都(dou)可(ke)(ke)以(yi)組成220伏。這個系統可(ke)(ke)以(yi)形成三種電(dian)(dian)(dian)源(yuan)(yuan)：即單(dan)相(xiang)(xiang)220伏電(dian)(dian)(dian)源(yuan)(yuan)，單(dan)相(xiang)(xiang)380伏電(dian)(dian)(dian)源(yuan)(yuan)，三相(xiang)(xiang)380伏電(dian)(dian)(dian)源(yuan)(yuan)，第(di) I 種家用(yong)比(bi)較多，第(di)三種工廠里電(dian)(dian)(dian)機類用(yong)得多，第(di)二種用(yong)得少(shao)，只有(you)交(jiao)流電(dian)(dian)(dian)焊機經(jing)常用(yong)到(dao)單(dan)相(xiang)(xiang)380伏電(dian)(dian)(dian)源(yuan)(yuan)。