Cores Used by Butler Winding: U and UI Cores
These shapes are available in lamination materials (forÂ stacking), powdered material (typically powdered iron), and ferrite materials. In laminated form, their features areÂ similar to that of the âCâ core discussed in a prior section. Heat dissipation is excellent. There is lots of room available for lead wires. Self-shielding is poor. âUâ cores have two core legs. Coils can be placed over either or both legs. Using coils on separate legs is great for high voltage isolation between coils. The mean turn length of two coils on separate legs (sharing the whole winding window) is smaller than 1 coil on one leg (occupying the whole winding window), hence the two coils connected in series has less winding resistance. âUâ (and âCâ) cores may be used for âsplit-coreâ current transformers.