三相電加熱管

        380伏三相(xiang)四線(xian)電(dian)(dian)路中(zhong)，任意(yi)兩根火線(xian)之間(jian)(jian)的電(dian)(dian)壓都是(shi)380伏，任意(yi)一根火線(xian)與(yu)零線(xian)之間(jian)(jian)都可(ke)以組(zu)成(cheng)220伏。這個系統可(ke)以形(xing)成(cheng)三種(zhong)電(dian)(dian)源：即(ji)單(dan)相(xiang)220伏電(dian)(dian)源，單(dan)相(xiang)380伏電(dian)(dian)源，三相(xiang)380伏電(dian)(dian)源，第(di)(di) I 種(zhong)家用(yong)(yong)比較多，第(di)(di)三種(zhong)工廠里電(dian)(dian)機類用(yong)(yong)得多，第(di)(di)二種(zhong)用(yong)(yong)得少，只(zhi)有(you)交流電(dian)(dian)焊機經常(chang)用(yong)(yong)到(dao)單(dan)相(xiang)380伏電(dian)(dian)源。