Lecture 3 Magnetic Circuits
Lecture 3 Magnetic Circuits
Lecture 3 Magnetic Circuits
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Table : Analogy between <strong>Magnetic</strong> and Electric circuits<br />
Electric circuit<br />
<strong>Magnetic</strong> circuit<br />
I=current (A)<br />
= flux (wb)<br />
V= emf (V)<br />
F = mmf (AT)<br />
R= resistance ()<br />
R = reluctance (AT/wb)<br />
= conductivity (S/m) µ = permeability (H/m)<br />
Self study: Example 4.1, 4.2, 4.4<br />
<strong>Magnetic</strong> Circuit with Air-gap and Flux Fringing<br />
At an air-gap in a magnetic core, the flux fringes out into neighboring air paths as<br />
shown in Figure. The result is non-uniform flux density in the air-gap (decreasing<br />
outward), enlargement of the effective air-gap area and a decrease in the average gap<br />
flux density. The fringing effect also disturbs the core flux pattern to some depth near<br />
the gap. The effect of fringing increases with the air-gap length.<br />
Fig: Flux fringing at the air-gap<br />
Dr. Ahsan Page 4
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