三相電加熱管

        380伏(fu)(fu)(fu)三相四線電(dian)(dian)(dian)路(lu)中，任(ren)意兩根火線之(zhi)間(jian)的電(dian)(dian)(dian)壓都(dou)是380伏(fu)(fu)(fu)，任(ren)意一(yi)根火線與零線之(zhi)間(jian)都(dou)可(ke)(ke)以組成220伏(fu)(fu)(fu)。這個系統可(ke)(ke)以形成三種(zhong)電(dian)(dian)(dian)源(yuan)(yuan)：即單(dan)相220伏(fu)(fu)(fu)電(dian)(dian)(dian)源(yuan)(yuan)，單(dan)相380伏(fu)(fu)(fu)電(dian)(dian)(dian)源(yuan)(yuan)，三相380伏(fu)(fu)(fu)電(dian)(dian)(dian)源(yuan)(yuan)，第(di) I 種(zhong)家用比(bi)較(jiao)多，第(di)三種(zhong)工廠里電(dian)(dian)(dian)機(ji)類用得多，第(di)二種(zhong)用得少，只有交(jiao)流(liu)電(dian)(dian)(dian)焊機(ji)經常(chang)用到(dao)單(dan)相380伏(fu)(fu)(fu)電(dian)(dian)(dian)源(yuan)(yuan)。