三相電加熱管

        380伏三相(xiang)(xiang)四線(xian)(xian)電(dian)(dian)路中，任意兩根(gen)(gen)火(huo)線(xian)(xian)之(zhi)(zhi)間的電(dian)(dian)壓都是(shi)380伏，任意一根(gen)(gen)火(huo)線(xian)(xian)與(yu)零線(xian)(xian)之(zhi)(zhi)間都可以組(zu)成220伏。這(zhe)個系統可以形成三種電(dian)(dian)源(yuan)(yuan)：即單相(xiang)(xiang)220伏電(dian)(dian)源(yuan)(yuan)，單相(xiang)(xiang)380伏電(dian)(dian)源(yuan)(yuan)，三相(xiang)(xiang)380伏電(dian)(dian)源(yuan)(yuan)，第 I 種家用(yong)比較(jiao)多(duo)，第三種工廠里電(dian)(dian)機類用(yong)得多(duo)，第二種用(yong)得少(shao)，只(zhi)有交流電(dian)(dian)焊機經常用(yong)到單相(xiang)(xiang)380伏電(dian)(dian)源(yuan)(yuan)。