Tooth pulsations in rotating machines surface iron losses with reference to laminated materials

G. E. Luke: These two papers on iron losses are very worthy papers in that their purpose is to give the designing engineers a knowledge of the stray losses which occur in a machine. These stray losses are very large in the case of some induction motors and in the case of turbo-generator and other high speed electric machines. The old d-c. machines had solid pole faces; the losses on those were large. The only thing that limited them and kept them down within reasonable value was the fact that they used large air gaps. But as the designs were improved, the air-gap was brought down, particularly with the use of t he commutating pole, and it was necessary to reduce these pole-face losses; this necessitated a laminated structure.