三相電加熱管

        380伏(fu)(fu)三相四線電(dian)(dian)路中(zhong)，任意兩根(gen)火線之間的電(dian)(dian)壓(ya)都是380伏(fu)(fu)，任意一根(gen)火線與零線之間都可以(yi)組(zu)成220伏(fu)(fu)。這個系統可以(yi)形成三種(zhong)(zhong)電(dian)(dian)源：即(ji)單(dan)相220伏(fu)(fu)電(dian)(dian)源，單(dan)相380伏(fu)(fu)電(dian)(dian)源，三相380伏(fu)(fu)電(dian)(dian)源，第 I 種(zhong)(zhong)家用比較多，第三種(zhong)(zhong)工廠里電(dian)(dian)機(ji)類(lei)用得多，第二種(zhong)(zhong)用得少，只有交流(liu)電(dian)(dian)焊機(ji)經(jing)常用到單(dan)相380伏(fu)(fu)電(dian)(dian)源。