三相電加熱管

        380伏(fu)(fu)三相四(si)線(xian)電(dian)(dian)(dian)路中，任意兩根火(huo)線(xian)之間(jian)的電(dian)(dian)(dian)壓(ya)都(dou)是380伏(fu)(fu)，任意一根火(huo)線(xian)與(yu)零線(xian)之間(jian)都(dou)可以(yi)組成220伏(fu)(fu)。這個(ge)系(xi)統可以(yi)形成三種電(dian)(dian)(dian)源(yuan)：即單相220伏(fu)(fu)電(dian)(dian)(dian)源(yuan)，單相380伏(fu)(fu)電(dian)(dian)(dian)源(yuan)，三相380伏(fu)(fu)電(dian)(dian)(dian)源(yuan)，第(di) I 種家用(yong)(yong)比(bi)較多(duo)，第(di)三種工(gong)廠(chang)里電(dian)(dian)(dian)機類用(yong)(yong)得多(duo)，第(di)二(er)種用(yong)(yong)得少，只有(you)交流電(dian)(dian)(dian)焊機經常用(yong)(yong)到單相380伏(fu)(fu)電(dian)(dian)(dian)源(yuan)。