The leakage flux between parallel pole-cores of circular cross-section

Some of the formulae used by designers for the purpose of calculating the leakage flux passing between circular pole-cores in salient-pole machines are far from satisfactory, since they cause the flux to be considerably under-estimated. The object of this paper is to draw attention to formulae and curves from which the permeance of the leakage paths can be found with high accuracy, the results being derived by simple mathematical methods. A critical comparison of the old with the new formula? is given, illustrated by a numerical example to show the use of the new results in practice.