Basic Electrical Theory MAGNETIC CIRCUITSExample: A coil has an mmf of 600 At, and a reluctance of 3 x 106 At/Wb.Find the total flux F.Solution:FmmfRF600At3 x 106At/Wb200 x 106 Wb200µWbBHMagnetizationCurveThe BH Magnetization Curve (Figure 27) shows how much flux density (B) results fromincreasing the flux intensity (H). The curves in Figure 27 are for two types of soft iron coresplotted for typical values. The curve for soft iron 1 shows that flux density B increases rapidlywith an increase in flux intensity H, before the core saturates, or develops a "knee." Thereafter,an increase in flux intensity H has little or no effect on flux density B. Soft iron 2 needs a muchlarger increase in flux intensity H before it reaches its saturation level at H = 5000 At/m, B =0.3 T.Air, which is nonmagnetic, has a very low BH profile, as shown in Figure 27.Figure 27 Typical BH Curve for Two Types of Soft IronRev. 0 Page 39 ES-01
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