Page 11 - Solutions Manual to accompany Electric Machinery Fundamentals

SOLUTION The two coils on this core are would so that their magnetomotive forces are additive, so the
total magnetomotive force on this core is

 F Ni   N i  600 t 0.5 A   200 t 1.00 A  500 A t 
TOT 1 1 2 2
The total reluctance in the core is
l 2.60 m

 R   76.6 kA t/Wb


TOT  A  0 1200 4  10  7   H/m 0.15 m 0.15 m 
r
and the flux in the core is:

  F TOT  500 A t  0.00653 Wb

R TOT 76.6 kA t/Wb
1-8. A core with three legs is shown in Figure P1-5. Its depth is 5 cm, and there are 100 turns on the leftmost
leg. The relative permeability of the core can be assumed to be 2000 and constant. What flux exists in
each of the three legs of the core? What is the flux density in each of the legs? Assume a 5% increase in
the effective area of the air gap due to fringing effects.

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