三相電加熱管

        380伏(fu)三相(xiang)(xiang)(xiang)四線(xian)電(dian)(dian)(dian)路中(zhong)，任意(yi)兩根火(huo)線(xian)之間的電(dian)(dian)(dian)壓都是380伏(fu)，任意(yi)一根火(huo)線(xian)與(yu)零線(xian)之間都可以組成(cheng)220伏(fu)。這個(ge)系(xi)統可以形成(cheng)三種電(dian)(dian)(dian)源(yuan)：即(ji)單(dan)相(xiang)(xiang)(xiang)220伏(fu)電(dian)(dian)(dian)源(yuan)，單(dan)相(xiang)(xiang)(xiang)380伏(fu)電(dian)(dian)(dian)源(yuan)，三相(xiang)(xiang)(xiang)380伏(fu)電(dian)(dian)(dian)源(yuan)，第(di) I 種家用(yong)比(bi)較多，第(di)三種工廠里電(dian)(dian)(dian)機(ji)類用(yong)得多，第(di)二種用(yong)得少，只有(you)交流電(dian)(dian)(dian)焊機(ji)經(jing)常用(yong)到單(dan)相(xiang)(xiang)(xiang)380伏(fu)電(dian)(dian)(dian)源(yuan)。