三相電加熱管

        380伏(fu)(fu)三(san)(san)相四線(xian)電(dian)(dian)(dian)路(lu)中，任意兩根火(huo)線(xian)之間(jian)的電(dian)(dian)(dian)壓都(dou)是380伏(fu)(fu)，任意一根火(huo)線(xian)與零(ling)線(xian)之間(jian)都(dou)可以組成220伏(fu)(fu)。這個系(xi)統可以形成三(san)(san)種(zhong)電(dian)(dian)(dian)源(yuan)：即(ji)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(san)(san)相380伏(fu)(fu)電(dian)(dian)(dian)源(yuan)，第(di) I 種(zhong)家(jia)用(yong)比較多，第(di)三(san)(san)種(zhong)工廠里(li)電(dian)(dian)(dian)機(ji)類用(yong)得多，第(di)二種(zhong)用(yong)得少，只有交流(liu)電(dian)(dian)(dian)焊機(ji)經(jing)常用(yong)到單相380伏(fu)(fu)電(dian)(dian)(dian)源(yuan)。