三相電加熱管

        380伏三相四線電(dian)(dian)(dian)(dian)路(lu)中，任意(yi)(yi)兩根火線之間(jian)的電(dian)(dian)(dian)(dian)壓都是380伏，任意(yi)(yi)一根火線與零線之間(jian)都可以組成(cheng)220伏。這個(ge)系統可以形成(cheng)三種電(dian)(dian)(dian)(dian)源(yuan)：即(ji)單(dan)相220伏電(dian)(dian)(dian)(dian)源(yuan)，單(dan)相380伏電(dian)(dian)(dian)(dian)源(yuan)，三相380伏電(dian)(dian)(dian)(dian)源(yuan)，第 I 種家用(yong)比較多，第三種工廠里(li)電(dian)(dian)(dian)(dian)機(ji)類用(yong)得多，第二(er)種用(yong)得少，只有交流電(dian)(dian)(dian)(dian)焊機(ji)經常用(yong)到單(dan)相380伏電(dian)(dian)(dian)(dian)源(yuan)。