三相電加熱管

        380伏(fu)(fu)三相(xiang)(xiang)四線(xian)電(dian)(dian)(dian)路中，任(ren)意兩(liang)根(gen)火(huo)線(xian)之間的(de)電(dian)(dian)(dian)壓都是380伏(fu)(fu)，任(ren)意一根(gen)火(huo)線(xian)與(yu)零線(xian)之間都可(ke)以組成220伏(fu)(fu)。這(zhe)個(ge)系(xi)統(tong)可(ke)以形成三種(zhong)電(dian)(dian)(dian)源(yuan)：即單(dan)相(xiang)(xiang)220伏(fu)(fu)電(dian)(dian)(dian)源(yuan)，單(dan)相(xiang)(xiang)380伏(fu)(fu)電(dian)(dian)(dian)源(yuan)，三相(xiang)(xiang)380伏(fu)(fu)電(dian)(dian)(dian)源(yuan)，第(di) I 種(zhong)家用(yong)(yong)比較多，第(di)三種(zhong)工廠(chang)里電(dian)(dian)(dian)機(ji)類用(yong)(yong)得(de)(de)多，第(di)二種(zhong)用(yong)(yong)得(de)(de)少，只(zhi)有交流電(dian)(dian)(dian)焊(han)機(ji)經常用(yong)(yong)到單(dan)相(xiang)(xiang)380伏(fu)(fu)電(dian)(dian)(dian)源(yuan)。