三相電加熱管

        380伏(fu)(fu)(fu)三(san)相四線(xian)(xian)電(dian)(dian)(dian)(dian)路(lu)中，任(ren)意(yi)兩(liang)根(gen)(gen)火線(xian)(xian)之間(jian)的電(dian)(dian)(dian)(dian)壓都是380伏(fu)(fu)(fu)，任(ren)意(yi)一(yi)根(gen)(gen)火線(xian)(xian)與零線(xian)(xian)之間(jian)都可以組成(cheng)220伏(fu)(fu)(fu)。這個系統(tong)可以形成(cheng)三(san)種(zhong)電(dian)(dian)(dian)(dian)源(yuan)(yuan)：即單(dan)相220伏(fu)(fu)(fu)電(dian)(dian)(dian)(dian)源(yuan)(yuan)，單(dan)相380伏(fu)(fu)(fu)電(dian)(dian)(dian)(dian)源(yuan)(yuan)，三(san)相380伏(fu)(fu)(fu)電(dian)(dian)(dian)(dian)源(yuan)(yuan)，第(di) I 種(zhong)家用(yong)比較多(duo)(duo)，第(di)三(san)種(zhong)工廠里電(dian)(dian)(dian)(dian)機(ji)類用(yong)得多(duo)(duo)，第(di)二種(zhong)用(yong)得少，只有交(jiao)流電(dian)(dian)(dian)(dian)焊機(ji)經常用(yong)到單(dan)相380伏(fu)(fu)(fu)電(dian)(dian)(dian)(dian)源(yuan)(yuan)。