三相電加熱管

        380伏(fu)(fu)(fu)三相(xiang)四線(xian)電(dian)(dian)(dian)路中(zhong)，任(ren)意兩根火線(xian)之間的電(dian)(dian)(dian)壓都是(shi)380伏(fu)(fu)(fu)，任(ren)意一根火線(xian)與零(ling)線(xian)之間都可以組成(cheng)220伏(fu)(fu)(fu)。這個系統可以形成(cheng)三種(zhong)電(dian)(dian)(dian)源：即單相(xiang)220伏(fu)(fu)(fu)電(dian)(dian)(dian)源，單相(xiang)380伏(fu)(fu)(fu)電(dian)(dian)(dian)源，三相(xiang)380伏(fu)(fu)(fu)電(dian)(dian)(dian)源，第(di) I 種(zhong)家用比(bi)較(jiao)多，第(di)三種(zhong)工廠里電(dian)(dian)(dian)機類(lei)用得多，第(di)二種(zhong)用得少，只有交流(liu)電(dian)(dian)(dian)焊(han)機經常用到單相(xiang)380伏(fu)(fu)(fu)電(dian)(dian)(dian)源。