Notes on the testing of tramway motors, and an investigation into their characteristic properties

Introductory remarks¿Definition of ¿rating of tramway motors¿¿Testing-frame¿Disadvantage of the Hopkinson-method¿Connections employed¿Description of test¿Reduction to standard voltage and standard temperature¿Example¿Results tabulated, Tables, I.¿VIII., plotted Figs. 3, 4¿Leading features of motors under consideration¿Connections for testing with less than 500 volts¿Separation of losses, Note I.¿Starting current¿Test for similarity of two motors used¿Examples, Tables IX., X.¿Effect of temperature on full-load efficiency¿Prony brake¿Determination of thermal characteristic¿Correction for cooling¿Flashing of motors¿Reversal of direction of rotation¿Volt-ampere characteristic, and determination of ampere¿R/n curve¿Latter very nearly straight line¿Deduction therefrom, Note 2¿Determination of retarding torque, motors acting as electric brakes¿Coefficients of adhesion in practice¿Particular case as example¿Change of velocity and distance traversed under varying accelerations, Note 3¿Tractive effort diagrams¿Allowance for angular acceleration of rotating parts¿Best shape of efficiency curve¿Diagram of controller positions for different routes¿Average current over route¿Current for minimum loss¿Graphical methods of studying acceleration and retardation periods¿Importance in connection with railways¿Possible economies to be effected by studying manipulation of controller¿Examples, Tables XI., XII.¿Approximate formulÿ¿Comparison with graphical methods, Table XIII.