三相電加熱管

        380伏(fu)(fu)三(san)(san)相四線電(dian)(dian)路中，任(ren)(ren)意(yi)兩根火(huo)線之間的電(dian)(dian)壓都(dou)是380伏(fu)(fu)，任(ren)(ren)意(yi)一根火(huo)線與零線之間都(dou)可以組成(cheng)(cheng)220伏(fu)(fu)。這個系統可以形成(cheng)(cheng)三(san)(san)種電(dian)(dian)源(yuan)(yuan)：即單(dan)相220伏(fu)(fu)電(dian)(dian)源(yuan)(yuan)，單(dan)相380伏(fu)(fu)電(dian)(dian)源(yuan)(yuan)，三(san)(san)相380伏(fu)(fu)電(dian)(dian)源(yuan)(yuan)，第(di) I 種家用(yong)比較多，第(di)三(san)(san)種工廠里電(dian)(dian)機(ji)類用(yong)得(de)多，第(di)二種用(yong)得(de)少(shao)，只有(you)交(jiao)流電(dian)(dian)焊(han)機(ji)經(jing)常用(yong)到(dao)單(dan)相380伏(fu)(fu)電(dian)(dian)源(yuan)(yuan)。