三相電加熱管

        380伏(fu)三相(xiang)四線(xian)(xian)電(dian)(dian)路中，任(ren)意兩根(gen)火(huo)線(xian)(xian)之間的電(dian)(dian)壓都(dou)是380伏(fu)，任(ren)意一根(gen)火(huo)線(xian)(xian)與零線(xian)(xian)之間都(dou)可以組(zu)成220伏(fu)。這個系統可以形成三種(zhong)電(dian)(dian)源(yuan)：即單相(xiang)220伏(fu)電(dian)(dian)源(yuan)，單相(xiang)380伏(fu)電(dian)(dian)源(yuan)，三相(xiang)380伏(fu)電(dian)(dian)源(yuan)，第 I 種(zhong)家用(yong)比較(jiao)多(duo)，第三種(zhong)工廠里(li)電(dian)(dian)機類用(yong)得(de)多(duo)，第二種(zhong)用(yong)得(de)少，只有交流電(dian)(dian)焊機經常用(yong)到單相(xiang)380伏(fu)電(dian)(dian)源(yuan)。