三相電加熱管

        380伏(fu)三相四線(xian)(xian)電(dian)(dian)(dian)(dian)路(lu)中，任(ren)意(yi)兩根(gen)火線(xian)(xian)之(zhi)間的電(dian)(dian)(dian)(dian)壓都(dou)是380伏(fu)，任(ren)意(yi)一根(gen)火線(xian)(xian)與零線(xian)(xian)之(zhi)間都(dou)可以組成220伏(fu)。這個系統可以形(xing)成三種(zhong)電(dian)(dian)(dian)(dian)源：即(ji)單相220伏(fu)電(dian)(dian)(dian)(dian)源，單相380伏(fu)電(dian)(dian)(dian)(dian)源，三相380伏(fu)電(dian)(dian)(dian)(dian)源，第(di) I 種(zhong)家(jia)用(yong)比較多，第(di)三種(zhong)工(gong)廠(chang)里電(dian)(dian)(dian)(dian)機類用(yong)得(de)多，第(di)二種(zhong)用(yong)得(de)少，只有交流電(dian)(dian)(dian)(dian)焊機經(jing)常用(yong)到單相380伏(fu)電(dian)(dian)(dian)(dian)源。