Cores Used by Butler Winding: EP Type
The âEPâ core design combines the self-shielding feature ofÂ a pot core with the coil lead accessibility of âEâ 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 âEPâ 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. âEPâ 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 âEPâ core and coil. Mounted in this way, the âEPâ shielding comes very close to that of a âPotâ core.
Once mounted the coils becomes completely enclosed. Consequently, heat dissipation is poor.
The âEPâ core has a round center leg to minimize winding losses.