三相電加熱管

        380伏(fu)(fu)三相(xiang)四線(xian)(xian)電(dian)(dian)(dian)(dian)(dian)路中，任(ren)意(yi)兩(liang)根火線(xian)(xian)之間(jian)的電(dian)(dian)(dian)(dian)(dian)壓都(dou)是380伏(fu)(fu)，任(ren)意(yi)一(yi)根火線(xian)(xian)與零線(xian)(xian)之間(jian)都(dou)可(ke)以(yi)組(zu)成220伏(fu)(fu)。這(zhe)個系統可(ke)以(yi)形成三種(zhong)電(dian)(dian)(dian)(dian)(dian)源：即(ji)單相(xiang)220伏(fu)(fu)電(dian)(dian)(dian)(dian)(dian)源，單相(xiang)380伏(fu)(fu)電(dian)(dian)(dian)(dian)(dian)源，三相(xiang)380伏(fu)(fu)電(dian)(dian)(dian)(dian)(dian)源，第(di) I 種(zhong)家用比(bi)較多，第(di)三種(zhong)工廠(chang)里電(dian)(dian)(dian)(dian)(dian)機(ji)類用得(de)多，第(di)二種(zhong)用得(de)少，只(zhi)有(you)交(jiao)流電(dian)(dian)(dian)(dian)(dian)焊機(ji)經常(chang)用到單相(xiang)380伏(fu)(fu)電(dian)(dian)(dian)(dian)(dian)源。