三相電加熱管

        380伏(fu)三相四線(xian)電(dian)(dian)(dian)路中，任(ren)意兩根(gen)火線(xian)之間(jian)的電(dian)(dian)(dian)壓(ya)都是(shi)380伏(fu)，任(ren)意一根(gen)火線(xian)與(yu)零線(xian)之間(jian)都可(ke)以組(zu)成(cheng)220伏(fu)。這個(ge)系統可(ke)以形(xing)成(cheng)三種(zhong)(zhong)電(dian)(dian)(dian)源(yuan)：即單(dan)(dan)相220伏(fu)電(dian)(dian)(dian)源(yuan)，單(dan)(dan)相380伏(fu)電(dian)(dian)(dian)源(yuan)，三相380伏(fu)電(dian)(dian)(dian)源(yuan)，第 I 種(zhong)(zhong)家用比較多，第三種(zhong)(zhong)工廠里電(dian)(dian)(dian)機類(lei)用得多，第二種(zhong)(zhong)用得少(shao)，只有交(jiao)流(liu)電(dian)(dian)(dian)焊機經常(chang)用到單(dan)(dan)相380伏(fu)電(dian)(dian)(dian)源(yuan)。