"The higher the power rating of a silicon steel transformer core, the greater its efficiency."

For silicon steel transformer cores, as the power rating increases, coils can be installed separately on both sides of the core. This allows the total number of turns to be distributed across two winding bobbins, thereby reducing the average turn length per bobbin and decreasing copper losses.

Furthermore, if two symmetrical coils are wound on separate bobbins, perfect symmetry can be achieved. Transformers made with four-piece ED-type silicon steel laminations are shorter but wider than CD-type transformers. Additionally, because the coils are mounted in the center of the laminations with an external magnetic path, leakage flux is minimized, resulting in lower overall electromagnetic interference. However, since all coils are wound on a single thick bobbin, the average turn length is longer, leading to higher copper losses.

Silicon steel transformer cores offer compact size, light weight, and high efficiency. From an assembly perspective, E-type silicon steel (also known as shell-type or Japanese-standard laminations) has the primary advantage of housing both primary and secondary windings on a single common bobbin, achieving a high window space factor. The laminations form a protective shell around the windings, preventing mechanical damage. Meanwhile, the large surface area facilitates better heat dissipation, and the magnetic field divergence is minimal. However, it suffers from higher primary-to-secondary leakage inductance and greater susceptibility to external magnetic interference.