三相電加熱管

        380伏(fu)(fu)三相(xiang)四線電(dian)(dian)(dian)(dian)路中(zhong)，任意兩根(gen)火線之間(jian)的電(dian)(dian)(dian)(dian)壓都(dou)是380伏(fu)(fu)，任意一根(gen)火線與零線之間(jian)都(dou)可以組成220伏(fu)(fu)。這(zhe)個系(xi)統可以形成三種(zhong)電(dian)(dian)(dian)(dian)源(yuan)(yuan)：即單相(xiang)220伏(fu)(fu)電(dian)(dian)(dian)(dian)源(yuan)(yuan)，單相(xiang)380伏(fu)(fu)電(dian)(dian)(dian)(dian)源(yuan)(yuan)，三相(xiang)380伏(fu)(fu)電(dian)(dian)(dian)(dian)源(yuan)(yuan)，第(di) I 種(zhong)家用比較(jiao)多，第(di)三種(zhong)工廠里(li)電(dian)(dian)(dian)(dian)機類用得多，第(di)二種(zhong)用得少，只有交流電(dian)(dian)(dian)(dian)焊(han)機經常用到單相(xiang)380伏(fu)(fu)電(dian)(dian)(dian)(dian)源(yuan)(yuan)。