An account is given of an experimental investigation made on a direct-current machine, concerning current displacement (or, as some would say, eddy currents) in the conductors of the armature winding. The investigation is a sequel to a theoretical investigation previously published in theJournal. The method adopted is that of making measurements of current density at several levels in the slot; the method is described with regard to oscillograms and also r.m.s. values. A series of results, obtained under shortcircuit conditions, is reproduced, and it is shown that the oscillograms obtained represent variations of current density substantially in accord with thos.e predicted from theory. The investigation was extended to cover open-circuit and full-load conditions, and results are reproduced. The necessity for further investigations is discussed, whilst tentative general conclusions are arrived at which should be of assistance to designers of direct-current machines.
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