The flashing characteristics of series and compound-wound motors

This paper, to a certain extent, is in the nature of a log covering several years´ test on a line of dynamotors. The flashing characteristics of series and compound-wound motors are discussed with special reference to these tests. The principles derived from the study of these machines have, however, been applied successfully to other motors. Machines of this type are apt to have a critical flash point, depending upon the constants of the electric and magnetic circuits. The oscillograph has been used to determine the best relation of shunt to series field for a given difference of speed between full load and no load. Methods of improving the flashing characteristics of a given machine are discussed. In some cases it is shown that a damper on a series-wound motor gives better flashing characteristics. An attempt to explain the nature of a flashover on a d-c. machine is made.