三相電加熱管

        380伏(fu)(fu)三(san)相(xiang)四線(xian)電(dian)(dian)路(lu)中，任(ren)(ren)意兩根(gen)(gen)火(huo)線(xian)之間(jian)的(de)電(dian)(dian)壓都(dou)是(shi)380伏(fu)(fu)，任(ren)(ren)意一根(gen)(gen)火(huo)線(xian)與零線(xian)之間(jian)都(dou)可以組成220伏(fu)(fu)。這個(ge)系統可以形成三(san)種(zhong)(zhong)電(dian)(dian)源(yuan)(yuan)：即(ji)單相(xiang)220伏(fu)(fu)電(dian)(dian)源(yuan)(yuan)，單相(xiang)380伏(fu)(fu)電(dian)(dian)源(yuan)(yuan)，三(san)相(xiang)380伏(fu)(fu)電(dian)(dian)源(yuan)(yuan)，第(di)(di) I 種(zhong)(zhong)家用比較多(duo)，第(di)(di)三(san)種(zhong)(zhong)工廠里電(dian)(dian)機類(lei)用得多(duo)，第(di)(di)二種(zhong)(zhong)用得少，只有交流(liu)電(dian)(dian)焊機經常(chang)用到單相(xiang)380伏(fu)(fu)電(dian)(dian)源(yuan)(yuan)。