三相電加熱管

        380伏三相(xiang)(xiang)四(si)線(xian)電(dian)(dian)(dian)路中，任(ren)意(yi)兩(liang)根火線(xian)之(zhi)間(jian)的電(dian)(dian)(dian)壓都是380伏，任(ren)意(yi)一(yi)根火線(xian)與(yu)零線(xian)之(zhi)間(jian)都可以組成(cheng)220伏。這個系統可以形(xing)成(cheng)三種電(dian)(dian)(dian)源(yuan)：即單(dan)相(xiang)(xiang)220伏電(dian)(dian)(dian)源(yuan)，單(dan)相(xiang)(xiang)380伏電(dian)(dian)(dian)源(yuan)，三相(xiang)(xiang)380伏電(dian)(dian)(dian)源(yuan)，第 I 種家用(yong)(yong)比較多，第三種工廠里電(dian)(dian)(dian)機(ji)(ji)類用(yong)(yong)得多，第二種用(yong)(yong)得少，只有(you)交流電(dian)(dian)(dian)焊機(ji)(ji)經(jing)常(chang)用(yong)(yong)到單(dan)相(xiang)(xiang)380伏電(dian)(dian)(dian)源(yuan)。