三相電加熱管

        380伏(fu)三(san)相四(si)線(xian)電(dian)(dian)路中，任(ren)意兩根火線(xian)之間的電(dian)(dian)壓都是380伏(fu)，任(ren)意一根火線(xian)與零線(xian)之間都可(ke)(ke)以(yi)組成(cheng)220伏(fu)。這個系統可(ke)(ke)以(yi)形成(cheng)三(san)種(zhong)電(dian)(dian)源：即(ji)單相220伏(fu)電(dian)(dian)源，單相380伏(fu)電(dian)(dian)源，三(san)相380伏(fu)電(dian)(dian)源，第(di) I 種(zhong)家用(yong)比較多，第(di)三(san)種(zhong)工廠(chang)里電(dian)(dian)機類用(yong)得多，第(di)二種(zhong)用(yong)得少，只有交流電(dian)(dian)焊(han)機經常用(yong)到單相380伏(fu)電(dian)(dian)源。