Figure 1-30. Gap Placement using Different Core Configurations.

The B-H loops that are normally seen in the manufacturers’ catalogs are usually taken from a toroidal sample of the magnetic material. The toroidal core, without a gap, is the ideal shape to view the B-H loop of a given material. The material permeability, um, will be seen at its highest in the toroidal shape, as shown in Figure 1-31.