三相電加熱管

        380伏(fu)(fu)三相四(si)線(xian)電(dian)(dian)(dian)路中，任(ren)意兩根火線(xian)之間的電(dian)(dian)(dian)壓都(dou)是380伏(fu)(fu)，任(ren)意一根火線(xian)與(yu)零(ling)線(xian)之間都(dou)可以組成(cheng)220伏(fu)(fu)。這個系統可以形成(cheng)三種(zhong)電(dian)(dian)(dian)源：即單相220伏(fu)(fu)電(dian)(dian)(dian)源，單相380伏(fu)(fu)電(dian)(dian)(dian)源，三相380伏(fu)(fu)電(dian)(dian)(dian)源，第(di) I 種(zhong)家用比較多，第(di)三種(zhong)工(gong)廠里電(dian)(dian)(dian)機類用得多，第(di)二(er)種(zhong)用得少，只有交流電(dian)(dian)(dian)焊機經常(chang)用到(dao)單相380伏(fu)(fu)電(dian)(dian)(dian)源。