Photographing the Commutation Spark from Small Motors by High-speed Camera

We have done some attempts to understand the mechanism of commutation spark generation in universal motor from the image aspect using a high-speed camera. We have also mentioned about the generation of single and plural number of sparks at one commutator segment and the voltage between brush and commutator segment. The commutation sparks of the motor are generated with a sliding contact between brush and commutator segment in the moment that the segment is separated from the brush. And the width of the brush is just 10mm, this time, we were able to clarify position of the brush which sparks are generated and the relation between positive brush and negative brush.