GB315940A - Improvements relating to the commutation of electric currents - Google Patents

Abstract

315,940. Gill, J. F., Chaviara, J. N., and Teago, F. J. May 10, 1928. Armatures, short-circuited screens in cores of; commutators.-To improve commutation, an inductive closed circuit is magnetically coupled with each riser or with the leads connecting the risers to the armature winding. As shown in Fig. 2, the risers f connecting the armature winding d with a commutator segment e are electrically connected at k and insulated where they pass through slots in a laminated core g. The peripheral portion of each slot is surrounded by a closed copper loop h. The arrangement forms a small transformer in which the loop h constitutes a short-circuited secondary whereby energy is dissipated in the secondary during commutation instead of at the brush tips. The connection to the riser may form one or more turns interlinked with the magnetic circuit. Where the available space is too small for a device of the construction described, the riser or the connection thereto is insulated and around it is placed a thin strip of high permeability iron or alloy which has been covered with electrically deposited copper or with copper foil.