Development of sliding contact resistance testing equipment for carbon brush confluence ring

A carbon brush and a confluence ring form a pair of sliding electrical contacts. To reduce the contact resistance between the carbon brush and the confluence ring, the time for the running-in wear of the carbon brush increased during the machining process to increase the actual contact area. As a result, the welding and ablation failure between the carbon brush and the confluence ring happened under the impact of high current during service. To explore the effect of carbon brush wear on sliding electrical contact performance, it is necessary to monitor the dynamic contact resistance of the carbon brush and the confluence ring. In this paper, a set of 8-channel contact resistance testing equipment is developed. The device uses a relay array to achieve 1-8 channel gating and uses a data acquisition card to detect the contact resistance of each carbon brush and confluence ring pair combining with a four-point method. Based on the Labview software, it realizes the selection of acquisition channels, data acquisition card driving, real-time data processing, displaying, and storage. The range of contact resistance that this set of equipment can detect is 10mΩ ∼2Ω, and the accuracy can reach 1% of the full scale. Finally, the simulation experiments show that the testing equipment meets the technical requirements, and the continuous test runs stably and reliably. It can be used for the testing and research of the sliding contact resistance between the carbon brush and the confluence ring during the running-in wear process.