“EP” Type – Tranformer Cores

Cores Used by Butler Winding: EP Type

The “EP” core design combines the self-shielding feature of a pot core with the coil lead accessibility of “E” cores in a small package. The core wraps around the coil on the top,
bottom, and three sides of the coil; but leaves one side of the coil open to bring out wires. Although the one side is open, the coil is completely recessed into the core. Because of the one open side, The amount of self-shielding of the “EP” core (by itself) is less than that of the pot core. However, the self-shielding improves when a ground plane is placed over the open side. “EP” cores are usually mounted on a printed circuit board with the open side against the printed circuit board. If good shielding is required, a grounded section of copper is provided on the printed circuit board under the “EP” core and coil. Mounted in this way, the “EP” shielding comes very close to that of a “Pot” core.

Once mounted the coils becomes completely enclosed. Consequently, heat dissipation is poor.

The “EP” core has a round center leg to minimize winding losses.

Core Types Used by Butler Winding