三相電加熱管

        380伏三(san)相(xiang)(xiang)(xiang)四線電(dian)路中，任意(yi)兩根火線之(zhi)間的電(dian)壓都是380伏，任意(yi)一根火線與零線之(zhi)間都可以組成(cheng)(cheng)220伏。這個系統可以形成(cheng)(cheng)三(san)種(zhong)(zhong)電(dian)源(yuan)(yuan)：即單(dan)相(xiang)(xiang)(xiang)220伏電(dian)源(yuan)(yuan)，單(dan)相(xiang)(xiang)(xiang)380伏電(dian)源(yuan)(yuan)，三(san)相(xiang)(xiang)(xiang)380伏電(dian)源(yuan)(yuan)，第(di) I 種(zhong)(zhong)家(jia)用(yong)(yong)(yong)比較多(duo)，第(di)三(san)種(zhong)(zhong)工廠(chang)里電(dian)機類用(yong)(yong)(yong)得多(duo)，第(di)二種(zhong)(zhong)用(yong)(yong)(yong)得少，只有(you)交(jiao)流電(dian)焊機經常(chang)用(yong)(yong)(yong)到(dao)單(dan)相(xiang)(xiang)(xiang)380伏電(dian)源(yuan)(yuan)。