Repeat Example 1.7 but find the current i for B_c = 1.6 T. By what factor does the current have to be increased to result in this factor of 1.6 increase in flux density?

EXAMPLE 1.7

Assume that the core material in Example 1.1 is M-5 electrical steel, which has the de magne- tization curve of Fig. 1.10. Find the current i required to produce B = 1 T. Solution The value of Hc for B. = 1 T is read from Fig. 1.10 as H = 11 A turns/m The mmf drop for the core path is Fe = Hele = 11(0.3) = 3.3 A-turns Neglecting fringing, Bg = B and the mmf drop across the air gap is 1(5 x 10-4) = 396 A-turns 4 x 10-7 F = H8 = The required current is i= B8 Fe + F N = 399 500 = 0.80 A =