三相電加熱管

        380伏(fu)(fu)三(san)(san)相四(si)線(xian)電(dian)(dian)(dian)路中，任意(yi)(yi)兩根(gen)火(huo)線(xian)之間的電(dian)(dian)(dian)壓都(dou)是380伏(fu)(fu)，任意(yi)(yi)一根(gen)火(huo)線(xian)與(yu)零線(xian)之間都(dou)可(ke)以組成220伏(fu)(fu)。這個系(xi)統可(ke)以形(xing)成三(san)(san)種電(dian)(dian)(dian)源：即(ji)單相220伏(fu)(fu)電(dian)(dian)(dian)源，單相380伏(fu)(fu)電(dian)(dian)(dian)源，三(san)(san)相380伏(fu)(fu)電(dian)(dian)(dian)源，第(di) I 種家(jia)用(yong)比較多，第(di)三(san)(san)種工廠里電(dian)(dian)(dian)機類用(yong)得多，第(di)二種用(yong)得少，只(zhi)有交流電(dian)(dian)(dian)焊(han)機經常用(yong)到單相380伏(fu)(fu)電(dian)(dian)(dian)源。