三相電加熱管

        380伏(fu)(fu)三(san)相四線電(dian)(dian)(dian)路中(zhong)，任(ren)意兩根(gen)火線之(zhi)間(jian)的電(dian)(dian)(dian)壓都是380伏(fu)(fu)，任(ren)意一根(gen)火線與零線之(zhi)間(jian)都可(ke)(ke)以(yi)組成(cheng)(cheng)220伏(fu)(fu)。這(zhe)個系統可(ke)(ke)以(yi)形成(cheng)(cheng)三(san)種電(dian)(dian)(dian)源(yuan)(yuan)(yuan)：即單(dan)(dan)相220伏(fu)(fu)電(dian)(dian)(dian)源(yuan)(yuan)(yuan)，單(dan)(dan)相380伏(fu)(fu)電(dian)(dian)(dian)源(yuan)(yuan)(yuan)，三(san)相380伏(fu)(fu)電(dian)(dian)(dian)源(yuan)(yuan)(yuan)，第 I 種家用比(bi)較多(duo)，第三(san)種工廠里電(dian)(dian)(dian)機(ji)(ji)類用得(de)(de)多(duo)，第二種用得(de)(de)少，只有(you)交(jiao)流電(dian)(dian)(dian)焊(han)機(ji)(ji)經常用到單(dan)(dan)相380伏(fu)(fu)電(dian)(dian)(dian)源(yuan)(yuan)(yuan)。