Power Sources and Supplies: World Class Designs

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Chapter 10

Note that in Figure 10.10

, the p  1 and p  0.5 curves do not really have an “ optimum. ”

For these, the F

R

/ X (AC resistance) can be made even smaller as we increase X

(thickness). F

R

will in fact become much greater than 1. However, we see that for p  1

for example, no signifi cant reduction in AC resistance occurs if X exceeds about 2 , that

is, thickness of foil equal to twice the skin depth. We can make it thicker if we want, but

only for marginal improvement in the secondary winding losses. Further, in the process,

we may also take away available area for the primary windings (and any other ...