三相電加熱管

        380伏三(san)相四線(xian)電(dian)(dian)路中，任(ren)意(yi)兩(liang)根火(huo)線(xian)之間(jian)的電(dian)(dian)壓都(dou)是380伏，任(ren)意(yi)一根火(huo)線(xian)與(yu)零線(xian)之間(jian)都(dou)可(ke)以(yi)組(zu)成220伏。這個系統可(ke)以(yi)形成三(san)種(zhong)電(dian)(dian)源(yuan)(yuan)：即單相220伏電(dian)(dian)源(yuan)(yuan)，單相380伏電(dian)(dian)源(yuan)(yuan)，三(san)相380伏電(dian)(dian)源(yuan)(yuan)，第(di) I 種(zhong)家用(yong)比較(jiao)多(duo)，第(di)三(san)種(zhong)工廠里(li)電(dian)(dian)機(ji)類(lei)用(yong)得(de)多(duo)，第(di)二(er)種(zhong)用(yong)得(de)少，只有交(jiao)流電(dian)(dian)焊機(ji)經(jing)常用(yong)到單相380伏電(dian)(dian)源(yuan)(yuan)。