三相電加熱管

        380伏(fu)(fu)(fu)三相(xiang)(xiang)四線(xian)電(dian)(dian)(dian)(dian)(dian)路中，任(ren)意兩根火線(xian)之間(jian)的電(dian)(dian)(dian)(dian)(dian)壓都(dou)(dou)是380伏(fu)(fu)(fu)，任(ren)意一根火線(xian)與零線(xian)之間(jian)都(dou)(dou)可(ke)以組成220伏(fu)(fu)(fu)。這個系(xi)統可(ke)以形成三種(zhong)電(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)：即單相(xiang)(xiang)220伏(fu)(fu)(fu)電(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)，單相(xiang)(xiang)380伏(fu)(fu)(fu)電(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)，三相(xiang)(xiang)380伏(fu)(fu)(fu)電(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)，第(di) I 種(zhong)家用比較多(duo)，第(di)三種(zhong)工廠(chang)里電(dian)(dian)(dian)(dian)(dian)機類用得多(duo)，第(di)二種(zhong)用得少，只有交流(liu)電(dian)(dian)(dian)(dian)(dian)焊機經(jing)常用到單相(xiang)(xiang)380伏(fu)(fu)(fu)電(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)。