三相電加熱管

        380伏三相(xiang)(xiang)四線(xian)電(dian)(dian)(dian)(dian)(dian)路中，任意兩根(gen)火(huo)線(xian)之間的電(dian)(dian)(dian)(dian)(dian)壓(ya)都是380伏，任意一根(gen)火(huo)線(xian)與零線(xian)之間都可(ke)以(yi)組(zu)成220伏。這個(ge)系統可(ke)以(yi)形成三種(zhong)電(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)：即單相(xiang)(xiang)220伏電(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)，單相(xiang)(xiang)380伏電(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)，三相(xiang)(xiang)380伏電(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)，第 I 種(zhong)家用比較多(duo)，第三種(zhong)工廠里電(dian)(dian)(dian)(dian)(dian)機(ji)類用得多(duo)，第二種(zhong)用得少，只有交流電(dian)(dian)(dian)(dian)(dian)焊機(ji)經常用到單相(xiang)(xiang)380伏電(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)。