closed-iron transformer

例句：

1. 1. The closed-iron transformer is used for power transmission and distribution.
   封闭式铁芯变压器用于电力传输和分配。
2. 2. The closed-iron transformer has a high efficiency and low loss.
   封闭式铁芯变压器效率高、损耗低。
3. 3. The closed-iron transformer is an important component of the electrical system.
   封闭式铁芯变压器是电气系统的重要组件。