三相電加熱管

        380伏(fu)三相四線(xian)(xian)電(dian)(dian)路中(zhong)，任意(yi)(yi)兩根火線(xian)(xian)之(zhi)間的電(dian)(dian)壓(ya)都是380伏(fu)，任意(yi)(yi)一根火線(xian)(xian)與(yu)零(ling)線(xian)(xian)之(zhi)間都可以組成220伏(fu)。這(zhe)個系統(tong)可以形成三種電(dian)(dian)源(yuan)：即單相220伏(fu)電(dian)(dian)源(yuan)，單相380伏(fu)電(dian)(dian)源(yuan)，三相380伏(fu)電(dian)(dian)源(yuan)，第(di) I 種家用比較多，第(di)三種工廠里電(dian)(dian)機類(lei)用得多，第(di)二種用得少，只有交流電(dian)(dian)焊機經常(chang)用到單相380伏(fu)電(dian)(dian)源(yuan)。