A suggested scheme for reducing eddy-current power loss in transformer cores with a circul...

A suggested scheme for reducing eddy-current power loss in transformer cores with a circular cross section is to divide the cores into a large number of small insulated filamentary parts. As illustrated in Fig., the section shown in part (a) is replaced by that in part (b). Assuming that B(t) = B0 sin wt and that N filamentary areas fill 95% of the original cross-sectional area, find

a) the average eddy-current power loss in the section of core of height h in Fig.,

b) the total average eddy-current power loss in the N filamentary sections in Fig.

The magnetic field due to eddy currents is assumed to be negligible. (Hint: First find the current and power dissipated in the differential circular ring section of height h and width dr at radius r.)

FIGURE 1: Suggested eddy-current power-loss reduction scheme (Problem P.7-6).

(a)

FIGURE 2: Suggested eddy-current power-loss reduction scheme (Problem P.7-6).

(b)