The effect of fringing increases with the air-gap length. The fringing effect also disturbs the core flux pattern to some depth near the gap. The result is nonuniform flux density in the air-gap (decreasing outward), enlargement of the effective air-gap area and a decrease in the average gap flux density. These being of reluctance comparable to that of the gap. Special studies of leakage must be made for ac machines and transformers since their performance is affected by it.Īt an air-gap in a magnetic core, the flux fringes out into neighboring air paths as shown in Fig. Calculations concerning the main Magnetic Circuit Calculations are usually carried out with the effect of leakage flux either ignored or empirically accounted for. Leakage is characteristic of all magnetic circuits and can never be fully eliminated. This stray flux as already stated is called the leakage flux. In all practical Magnetic Circuit Calculations, most of the flux is confined to the intended path by use of magnetic cores but a small amount of flux always leaks through the surrounding air. Graphical/ numerical techniques have to be used in obtaining the solution of this problem. A little thought will reveal that there is no direct analytical solution to this problem because of the non-linear B-H characteristic of the magnetic material.
This kind of problem arises in magnetic amplifiers wherein this resultant flux is required to be determined owing to the given excitation on one or more control windings.
given geometry of the magnetic circuit and specified mmf. In the second category the flux (or flux density) is unknown and is required to be determined for a.
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