An Analysis of the Resistance of Sliding Electrical Contacts

This paper presents the conception of the sliding contact area as a velocity-dependent parameter and develops a method of assessing the variation of contact resistance with sliding velocity. Results of experimental work on sliding point contacts between carbon sliprings and carbon brushes are presented in the form of resistance-velocity characteristics. The percentage variation of contact area with peripheral velocity is computed from oscillograms of contact voltage. It is found that at high pressures the contact area is not affected by low sliding velocities, but starts falling off at high velocities while for low pressures there is a sharp decrease in area at low sliding velocities, but after the area has fallen to a small value it remains more or less constant as the velocity increases.