三相電加熱管

        380伏三(san)相(xiang)四(si)線電(dian)(dian)(dian)路中，任意(yi)兩根火線之間的電(dian)(dian)(dian)壓都(dou)是380伏，任意(yi)一根火線與零線之間都(dou)可(ke)以(yi)(yi)組成(cheng)220伏。這個(ge)系統可(ke)以(yi)(yi)形成(cheng)三(san)種(zhong)(zhong)電(dian)(dian)(dian)源(yuan)(yuan)：即(ji)單相(xiang)220伏電(dian)(dian)(dian)源(yuan)(yuan)，單相(xiang)380伏電(dian)(dian)(dian)源(yuan)(yuan)，三(san)相(xiang)380伏電(dian)(dian)(dian)源(yuan)(yuan)，第 I 種(zhong)(zhong)家用(yong)比較(jiao)多，第三(san)種(zhong)(zhong)工(gong)廠里(li)電(dian)(dian)(dian)機類用(yong)得(de)多，第二(er)種(zhong)(zhong)用(yong)得(de)少，只有交流(liu)電(dian)(dian)(dian)焊機經常用(yong)到單相(xiang)380伏電(dian)(dian)(dian)源(yuan)(yuan)。