Carbon brush performance and application in the pulp and paper environment

Direct current (DC) motors are used extensively throughout the pulp and paper industry. These motors are used in various applications such as fan pumps, press and winder motors. The maintenance requirements of the motors are different for each application. An important maintenance function regularly performed is the inspection of carbon brushes and commutators. Carbon brushes are critical to the operation of the paper machine with DC motors. Worn or failed brushes can make a paper machine inoperable and cost thousands of dollars per hour. This paper discusses the different theories used for carbon brush application in the paper industry. The strength and weaknesses of each brush application theory are also addressed. In the end the "black magic" of carbon brushes is revealed. The goal of this paper is to educate new and old maintenance personnel on carbon brush and commutator performance criteria and upkeep, hence reducing overall maintenance cost.