三相電加熱管

        380伏三(san)相四線(xian)(xian)電(dian)(dian)(dian)(dian)路中，任(ren)意兩根(gen)火線(xian)(xian)之間(jian)的電(dian)(dian)(dian)(dian)壓都(dou)是380伏，任(ren)意一根(gen)火線(xian)(xian)與零線(xian)(xian)之間(jian)都(dou)可以組成220伏。這個(ge)系統可以形(xing)成三(san)種(zhong)電(dian)(dian)(dian)(dian)源(yuan)：即單相220伏電(dian)(dian)(dian)(dian)源(yuan)，單相380伏電(dian)(dian)(dian)(dian)源(yuan)，三(san)相380伏電(dian)(dian)(dian)(dian)源(yuan)，第(di)(di) I 種(zhong)家用(yong)(yong)比較多，第(di)(di)三(san)種(zhong)工廠里電(dian)(dian)(dian)(dian)機(ji)類用(yong)(yong)得多，第(di)(di)二種(zhong)用(yong)(yong)得少，只有(you)交(jiao)流電(dian)(dian)(dian)(dian)焊機(ji)經常用(yong)(yong)到單相380伏電(dian)(dian)(dian)(dian)源(yuan)。