Commutation diagnosis in converter fed commutator motors from study of brush surface

Power converter-fed commutator motors have widespread use in the form of DC motors operating from rectifier or DC chopper supplies. Various nonideal operating conditions affect the proper commutation of current in the armature coils, thereby degrading the motor performance. Thus, in order to establish the nature of commutation of the machine and caution against impending failure, it is convenient to maintain a periodic check of the brush surface. This paper presents both a theoretical discussion and data from field experience to provide a primary basis for a novel approach by which commutation diagnosis may be made from studies of the motor's brush surface.