三相電加熱管

        380伏三相(xiang)四線(xian)電(dian)(dian)路中，任(ren)意兩根(gen)(gen)火線(xian)之間(jian)的(de)電(dian)(dian)壓(ya)都是380伏，任(ren)意一根(gen)(gen)火線(xian)與零線(xian)之間(jian)都可(ke)以組成(cheng)220伏。這個系統(tong)可(ke)以形(xing)成(cheng)三種電(dian)(dian)源(yuan)：即單相(xiang)220伏電(dian)(dian)源(yuan)，單相(xiang)380伏電(dian)(dian)源(yuan)，三相(xiang)380伏電(dian)(dian)源(yuan)，第 I 種家用(yong)(yong)比(bi)較多，第三種工廠里電(dian)(dian)機(ji)(ji)類用(yong)(yong)得(de)多，第二種用(yong)(yong)得(de)少，只有交流電(dian)(dian)焊機(ji)(ji)經常(chang)用(yong)(yong)到單相(xiang)380伏電(dian)(dian)源(yuan)。