三相電加熱管

        380伏(fu)三(san)相(xiang)四線電(dian)(dian)(dian)(dian)路中(zhong)，任意兩根(gen)火線之間(jian)的電(dian)(dian)(dian)(dian)壓都是380伏(fu)，任意一根(gen)火線與(yu)零線之間(jian)都可(ke)以(yi)組(zu)成220伏(fu)。這個系統可(ke)以(yi)形成三(san)種電(dian)(dian)(dian)(dian)源(yuan)(yuan)：即單(dan)相(xiang)220伏(fu)電(dian)(dian)(dian)(dian)源(yuan)(yuan)，單(dan)相(xiang)380伏(fu)電(dian)(dian)(dian)(dian)源(yuan)(yuan)，三(san)相(xiang)380伏(fu)電(dian)(dian)(dian)(dian)源(yuan)(yuan)，第(di)(di) I 種家用比(bi)較多，第(di)(di)三(san)種工廠里(li)電(dian)(dian)(dian)(dian)機(ji)類用得(de)多，第(di)(di)二(er)種用得(de)少，只有交(jiao)流電(dian)(dian)(dian)(dian)焊機(ji)經常用到單(dan)相(xiang)380伏(fu)電(dian)(dian)(dian)(dian)源(yuan)(yuan)。