三相電加熱管

        380伏(fu)三相四線(xian)(xian)電(dian)(dian)(dian)路(lu)中，任(ren)意兩根(gen)火線(xian)(xian)之(zhi)間的電(dian)(dian)(dian)壓(ya)都是380伏(fu)，任(ren)意一根(gen)火線(xian)(xian)與零線(xian)(xian)之(zhi)間都可以組成220伏(fu)。這個系統可以形(xing)成三種(zhong)電(dian)(dian)(dian)源(yuan)：即單相220伏(fu)電(dian)(dian)(dian)源(yuan)，單相380伏(fu)電(dian)(dian)(dian)源(yuan)，三相380伏(fu)電(dian)(dian)(dian)源(yuan)，第 I 種(zhong)家用(yong)比較多，第三種(zhong)工廠(chang)里電(dian)(dian)(dian)機(ji)類用(yong)得(de)(de)多，第二(er)種(zhong)用(yong)得(de)(de)少，只(zhi)有交(jiao)流電(dian)(dian)(dian)焊機(ji)經常用(yong)到單相380伏(fu)電(dian)(dian)(dian)源(yuan)。