三相電加熱管

        380伏三相(xiang)四(si)線(xian)電(dian)(dian)路中(zhong)，任(ren)意(yi)兩(liang)根(gen)火線(xian)之(zhi)間的電(dian)(dian)壓都(dou)是(shi)380伏，任(ren)意(yi)一根(gen)火線(xian)與(yu)零線(xian)之(zhi)間都(dou)可(ke)以組成220伏。這(zhe)個系統可(ke)以形成三種(zhong)(zhong)電(dian)(dian)源：即單(dan)相(xiang)220伏電(dian)(dian)源，單(dan)相(xiang)380伏電(dian)(dian)源，三相(xiang)380伏電(dian)(dian)源，第(di) I 種(zhong)(zhong)家用(yong)(yong)比較多(duo)，第(di)三種(zhong)(zhong)工廠里(li)電(dian)(dian)機類(lei)用(yong)(yong)得多(duo)，第(di)二種(zhong)(zhong)用(yong)(yong)得少，只有交(jiao)流(liu)電(dian)(dian)焊機經常(chang)用(yong)(yong)到單(dan)相(xiang)380伏電(dian)(dian)源。