三相電加熱管

        380伏三相(xiang)四線(xian)(xian)電(dian)(dian)路(lu)中，任意(yi)兩根(gen)火(huo)(huo)線(xian)(xian)之間(jian)的電(dian)(dian)壓都(dou)是380伏，任意(yi)一根(gen)火(huo)(huo)線(xian)(xian)與零線(xian)(xian)之間(jian)都(dou)可(ke)以組成220伏。這個系統(tong)可(ke)以形成三種(zhong)電(dian)(dian)源(yuan)(yuan)：即單(dan)相(xiang)220伏電(dian)(dian)源(yuan)(yuan)，單(dan)相(xiang)380伏電(dian)(dian)源(yuan)(yuan)，三相(xiang)380伏電(dian)(dian)源(yuan)(yuan)，第 I 種(zhong)家用比較多，第三種(zhong)工廠里電(dian)(dian)機類用得多，第二種(zhong)用得少(shao)，只有交流電(dian)(dian)焊機經常用到單(dan)相(xiang)380伏電(dian)(dian)源(yuan)(yuan)。