三相電加熱管

        380伏(fu)三(san)相(xiang)(xiang)(xiang)四線(xian)電(dian)(dian)(dian)路中，任意兩根(gen)火(huo)線(xian)之間的(de)電(dian)(dian)(dian)壓都是380伏(fu)，任意一(yi)根(gen)火(huo)線(xian)與零線(xian)之間都可以(yi)組成220伏(fu)。這個系統可以(yi)形成三(san)種(zhong)電(dian)(dian)(dian)源(yuan)：即(ji)單(dan)(dan)相(xiang)(xiang)(xiang)220伏(fu)電(dian)(dian)(dian)源(yuan)，單(dan)(dan)相(xiang)(xiang)(xiang)380伏(fu)電(dian)(dian)(dian)源(yuan)，三(san)相(xiang)(xiang)(xiang)380伏(fu)電(dian)(dian)(dian)源(yuan)，第(di) I 種(zhong)家用(yong)(yong)比較(jiao)多，第(di)三(san)種(zhong)工廠里(li)電(dian)(dian)(dian)機類用(yong)(yong)得多，第(di)二種(zhong)用(yong)(yong)得少，只有交流電(dian)(dian)(dian)焊機經常用(yong)(yong)到(dao)單(dan)(dan)相(xiang)(xiang)(xiang)380伏(fu)電(dian)(dian)(dian)源(yuan)。