Flashing of Railway Motors Caused by Brush jumping

Theories and concepts developed in connection with circuit rupturing by switches and circuit breakers are used to analyze the factors involved in the flashing of railway motors. The investigation is limited to cases where Flashing is caused by brush jumping, which occurs principally with railway motors. Voltage conditions as applying at the commutator circumference and as affecting the sustenance of an arc are studied for varying designs of main poles with different ratios of armature ampere turns to field ampere turns. The effect of load current and speed is subsequently taken into account. Actual test results are compared with the theories outlined. Finally, the modifying effect of certain secondary phenomena is discussed.