三相電加熱管

        380伏三(san)相四線(xian)電(dian)(dian)路中(zhong)，任(ren)意兩(liang)根火(huo)線(xian)之間的電(dian)(dian)壓都是380伏，任(ren)意一(yi)根火(huo)線(xian)與零線(xian)之間都可以組(zu)成220伏。這個系統可以形成三(san)種電(dian)(dian)源(yuan)(yuan)：即(ji)單相220伏電(dian)(dian)源(yuan)(yuan)，單相380伏電(dian)(dian)源(yuan)(yuan)，三(san)相380伏電(dian)(dian)源(yuan)(yuan)，第(di) I 種家(jia)用(yong)比較(jiao)多，第(di)三(san)種工廠里(li)電(dian)(dian)機類用(yong)得多，第(di)二種用(yong)得少，只有交流(liu)電(dian)(dian)焊(han)機經常(chang)用(yong)到單相380伏電(dian)(dian)源(yuan)(yuan)。