三相電加熱管

        380伏(fu)三相(xiang)四線電(dian)(dian)(dian)(dian)(dian)路中，任意兩(liang)根火線之間的電(dian)(dian)(dian)(dian)(dian)壓都是380伏(fu)，任意一根火線與零線之間都可以組成(cheng)220伏(fu)。這個系統可以形(xing)成(cheng)三種(zhong)電(dian)(dian)(dian)(dian)(dian)源(yuan)：即單相(xiang)220伏(fu)電(dian)(dian)(dian)(dian)(dian)源(yuan)，單相(xiang)380伏(fu)電(dian)(dian)(dian)(dian)(dian)源(yuan)，三相(xiang)380伏(fu)電(dian)(dian)(dian)(dian)(dian)源(yuan)，第(di) I 種(zhong)家用(yong)比(bi)較多，第(di)三種(zhong)工(gong)廠里電(dian)(dian)(dian)(dian)(dian)機(ji)類用(yong)得多，第(di)二種(zhong)用(yong)得少，只有交流電(dian)(dian)(dian)(dian)(dian)焊機(ji)經常用(yong)到(dao)單相(xiang)380伏(fu)電(dian)(dian)(dian)(dian)(dian)源(yuan)。