The primary conductor of this type of transformer is produced through the extrusion method, in which hairpins made of aluminum or copper are bent in an especial way. This product is called the bottom-core, for the cores and second windings are located in the bottom tank. The primary conductor is insulated with a proper insulating paper, allowing it to enjoy a high insulation resistance, low dielectric losses, and satisfactory aging properties. The advantages of these transformers are as follows:
 

1. Manufactured through technology transfer from ABB, Sweden.
2. A unique filling composition of oil and pure quartz grains is used, resulting in a compact design.
3. Products are hermetically sealed, which eliminates the need for regular maintenance procedures.
4. No oil change is required as the expansion room is filled with nitrogen.
5. High seismic withstand capability: The product’s center of gravity is located in the bottom tank of the product, making it resilient to earthquakes.
6. Different core specifications and quantities in line with customers’ needs can be designed.
7. Cores and primary winding are mechanically supported by using sand.
8. Simple installation with minimal maintenance

.Note: Special Designs can be offered based on customer's requests