三相電加熱管

        380伏(fu)三(san)相(xiang)(xiang)四線(xian)(xian)電(dian)(dian)路中，任(ren)意兩根火(huo)線(xian)(xian)之間的電(dian)(dian)壓都是(shi)380伏(fu)，任(ren)意一根火(huo)線(xian)(xian)與零線(xian)(xian)之間都可以組成220伏(fu)。這個系統可以形(xing)成三(san)種(zhong)電(dian)(dian)源(yuan)：即單(dan)相(xiang)(xiang)220伏(fu)電(dian)(dian)源(yuan)，單(dan)相(xiang)(xiang)380伏(fu)電(dian)(dian)源(yuan)，三(san)相(xiang)(xiang)380伏(fu)電(dian)(dian)源(yuan)，第 I 種(zhong)家用比較多，第三(san)種(zhong)工廠(chang)里電(dian)(dian)機(ji)類用得(de)多，第二種(zhong)用得(de)少，只(zhi)有交(jiao)流電(dian)(dian)焊機(ji)經(jing)常用到(dao)單(dan)相(xiang)(xiang)380伏(fu)電(dian)(dian)源(yuan)。