三相電加熱管

        380伏(fu)(fu)(fu)三(san)相(xiang)四線(xian)(xian)(xian)電(dian)(dian)路(lu)中，任意兩根火線(xian)(xian)(xian)之(zhi)間(jian)的電(dian)(dian)壓都是380伏(fu)(fu)(fu)，任意一根火線(xian)(xian)(xian)與(yu)零線(xian)(xian)(xian)之(zhi)間(jian)都可以組成(cheng)220伏(fu)(fu)(fu)。這個系統可以形成(cheng)三(san)種(zhong)電(dian)(dian)源(yuan)(yuan)：即單(dan)相(xiang)220伏(fu)(fu)(fu)電(dian)(dian)源(yuan)(yuan)，單(dan)相(xiang)380伏(fu)(fu)(fu)電(dian)(dian)源(yuan)(yuan)，三(san)相(xiang)380伏(fu)(fu)(fu)電(dian)(dian)源(yuan)(yuan)，第(di) I 種(zhong)家用(yong)(yong)比較多(duo)，第(di)三(san)種(zhong)工廠里電(dian)(dian)機(ji)類用(yong)(yong)得(de)多(duo)，第(di)二種(zhong)用(yong)(yong)得(de)少，只有(you)交(jiao)流電(dian)(dian)焊機(ji)經(jing)常用(yong)(yong)到(dao)單(dan)相(xiang)380伏(fu)(fu)(fu)電(dian)(dian)源(yuan)(yuan)。