Stray loss in direct-current commutating machines

With an ultimate view to selecting such multiplying factors as will permit of the stray loss values in direct-current apparatus being estimated without resorting to actual test, this paper presents: First. A brief description of the two elements comprising stray loss. Second. Methods of testing for stray loss with a short discussion as to the comparative accuracy of each. Third. Results of tests. The principal data are given in the form of curves showing the magnitude of stray loss at various loads on different machines. In connection with these results tentative suggestions are made as to possible multiplying factors. The paper is incomplete inasmuch as enough reliable data were not available at the time of writing to draw definite conclusions. Supplementary data will be presented at the Midwinter Convention.