Powdered Iron Cores

Iron alloys are ground and thoroughly mixed with a binding material, then pressed in a press to form a core. The binding material is an insulator; hence it reduces the eddy currents. This extends the useful frequency range of the iron. It can be used up to about five kilohertz depending on the A.C. kilogauss level, above 10 kilohertz at low A.C. gauss levels. The binding material also provides a distributed air gap in the core structure. The distributed gap is useful in D.C. applications. Powder iron is frequently used as ripple filter inductors in D.C. power supplies. The D.C. flux can be high as long as the A.C. flux is sufficiently small.

There are many types of powdered iron materials. Saturation can range from to 14 kilogauss depending on type.

Powdered iron cores are available in E, E-I, U and U-I shapes.

Core Types Used by Butler Winding