Part of maintaining electric motors and generators includes taking a brush survey to ensure that carbon brushes are in good working order. Canadian ElectroMechanical Company (CEMCO) provides a brush survey field service to diagnose and troubleshoot motor problems and to repair equipment before any serious problems can occur.

A carbon brush, or motor brush, is a vital component of motors and generators. It is a sliding contact that transmits an electrical current from stationary to rotating parts. Consisting of one or more carbon blocks, the brushes need to be seated properly and maintained to ensure the best performance.

With our brush survey, we provide the means to evaluate the condition and operating efficiency of the brush. A carbon brush has mechanical, electrical, and physical parameters that must be met; our team assesses these parameters when examining how the motor functions.

Using the wrong slip ring or commutator are just two mechanical issues that can negatively affect
carbon brush functionality. During our survey, we make sure the ring or commutator provides the right amount of friction, is defect-free and properly chamfered, and the run out is within the acceptable limits (Figure 1). Carbon brush pressure is calibrated for accuracy, and brush holders are inspected for the right height and clearance. Machines are evaluated for excessive vibrations so that misalignment of parts does not cause damage to the carbon brush.

The electrical system within the motor/generator is evaluated for voltage or contact drop, commutation in DC machines, and distribution of current brush contact surface, current density, and resistivity. If any of these factors are not at the correct levels, this can lead to brush damage—that’s why we carefully check that all electrical conditions are properly adjusted (Figure 2).

Our survey team performs thorough checks of the physical/chemical conditions around the motor to ensure that humidity, corrosive vapors or gases, oils and hydrocarbons, and contaminants don’t affect the carbon brush.

Canadian ElectroMechanical Company (CEMCO) provides state-of-the-art repair capabilities that serve a wide range of industries in several applications. We utilize the latest in computerized testing techniques, and our dedicated team has extensive experience in all aspects of electric motor repair, overhaul, remanufacturing, field service, and engineering support.

With service available 24/7, we are available to perform a carbon brush survey anytime you need it.