三相電加熱管

        380伏(fu)三(san)相(xiang)四線電(dian)(dian)路中(zhong)，任意兩(liang)根(gen)火(huo)線之間的電(dian)(dian)壓都是380伏(fu)，任意一根(gen)火(huo)線與(yu)零(ling)線之間都可(ke)以(yi)組(zu)成(cheng)(cheng)220伏(fu)。這個(ge)系統可(ke)以(yi)形成(cheng)(cheng)三(san)種(zhong)(zhong)(zhong)電(dian)(dian)源(yuan)：即單(dan)相(xiang)220伏(fu)電(dian)(dian)源(yuan)，單(dan)相(xiang)380伏(fu)電(dian)(dian)源(yuan)，三(san)相(xiang)380伏(fu)電(dian)(dian)源(yuan)，第(di)(di) I 種(zhong)(zhong)(zhong)家用比較多，第(di)(di)三(san)種(zhong)(zhong)(zhong)工(gong)廠(chang)里電(dian)(dian)機類用得(de)多，第(di)(di)二種(zhong)(zhong)(zhong)用得(de)少，只(zhi)有交流電(dian)(dian)焊機經常用到(dao)單(dan)相(xiang)380伏(fu)電(dian)(dian)源(yuan)。