三相電加熱管

        380伏(fu)(fu)三相四線電(dian)(dian)路中，任意兩根火線之(zhi)(zhi)間的電(dian)(dian)壓都是380伏(fu)(fu)，任意一根火線與零線之(zhi)(zhi)間都可以(yi)組成220伏(fu)(fu)。這個系統(tong)可以(yi)形成三種(zhong)(zhong)電(dian)(dian)源(yuan)：即單相220伏(fu)(fu)電(dian)(dian)源(yuan)，單相380伏(fu)(fu)電(dian)(dian)源(yuan)，三相380伏(fu)(fu)電(dian)(dian)源(yuan)，第 I 種(zhong)(zhong)家用(yong)(yong)比較多，第三種(zhong)(zhong)工廠里(li)電(dian)(dian)機(ji)類用(yong)(yong)得多，第二(er)種(zhong)(zhong)用(yong)(yong)得少，只有(you)交流(liu)電(dian)(dian)焊機(ji)經常(chang)用(yong)(yong)到(dao)單相380伏(fu)(fu)電(dian)(dian)源(yuan)。