三相電加熱管

        380伏(fu)(fu)(fu)(fu)三(san)(san)相(xiang)四線(xian)(xian)(xian)電(dian)(dian)路中，任意兩根火線(xian)(xian)(xian)之(zhi)間的電(dian)(dian)壓都(dou)是380伏(fu)(fu)(fu)(fu)，任意一(yi)根火線(xian)(xian)(xian)與零線(xian)(xian)(xian)之(zhi)間都(dou)可以組成220伏(fu)(fu)(fu)(fu)。這個系統可以形成三(san)(san)種(zhong)電(dian)(dian)源(yuan)(yuan)：即單(dan)(dan)相(xiang)220伏(fu)(fu)(fu)(fu)電(dian)(dian)源(yuan)(yuan)，單(dan)(dan)相(xiang)380伏(fu)(fu)(fu)(fu)電(dian)(dian)源(yuan)(yuan)，三(san)(san)相(xiang)380伏(fu)(fu)(fu)(fu)電(dian)(dian)源(yuan)(yuan)，第(di) I 種(zhong)家用(yong)比較多，第(di)三(san)(san)種(zhong)工廠里電(dian)(dian)機(ji)類(lei)用(yong)得(de)多，第(di)二種(zhong)用(yong)得(de)少，只有交(jiao)流電(dian)(dian)焊(han)機(ji)經常(chang)用(yong)到(dao)單(dan)(dan)相(xiang)380伏(fu)(fu)(fu)(fu)電(dian)(dian)源(yuan)(yuan)。