三相電加熱管

        380伏三相(xiang)(xiang)(xiang)(xiang)四線(xian)電(dian)路中，任(ren)意(yi)兩根火線(xian)之(zhi)間的電(dian)壓(ya)都(dou)是(shi)380伏，任(ren)意(yi)一根火線(xian)與零線(xian)之(zhi)間都(dou)可(ke)以組成220伏。這個系統可(ke)以形成三種(zhong)(zhong)電(dian)源(yuan)：即單相(xiang)(xiang)(xiang)(xiang)220伏電(dian)源(yuan)，單相(xiang)(xiang)(xiang)(xiang)380伏電(dian)源(yuan)，三相(xiang)(xiang)(xiang)(xiang)380伏電(dian)源(yuan)，第(di) I 種(zhong)(zhong)家用比(bi)較多，第(di)三種(zhong)(zhong)工(gong)廠(chang)里電(dian)機(ji)類用得多，第(di)二種(zhong)(zhong)用得少，只有交流電(dian)焊機(ji)經(jing)常用到單相(xiang)(xiang)(xiang)(xiang)380伏電(dian)源(yuan)。