三相電加熱管

        380伏(fu)(fu)(fu)三相四線(xian)(xian)電(dian)(dian)(dian)路中，任(ren)意兩根火(huo)線(xian)(xian)之間(jian)的電(dian)(dian)(dian)壓(ya)都是(shi)380伏(fu)(fu)(fu)，任(ren)意一根火(huo)線(xian)(xian)與零線(xian)(xian)之間(jian)都可以(yi)組成(cheng)220伏(fu)(fu)(fu)。這個系統可以(yi)形(xing)成(cheng)三種(zhong)電(dian)(dian)(dian)源(yuan)：即(ji)單相220伏(fu)(fu)(fu)電(dian)(dian)(dian)源(yuan)，單相380伏(fu)(fu)(fu)電(dian)(dian)(dian)源(yuan)，三相380伏(fu)(fu)(fu)電(dian)(dian)(dian)源(yuan)，第(di) I 種(zhong)家用比較多，第(di)三種(zhong)工廠里電(dian)(dian)(dian)機(ji)類(lei)用得多，第(di)二種(zhong)用得少，只有(you)交流電(dian)(dian)(dian)焊機(ji)經(jing)常用到單相380伏(fu)(fu)(fu)電(dian)(dian)(dian)源(yuan)。