Carbon brushes for single-phase energy storage motors

What is a carbon brush?

Also known as a motor brush, a carbon brush is a sliding contact that is used to transmit an electrical current from a static to a rotating part in a generator or motor. In DC machines, a carbon brush ensures a spark-free commutation. They can be made of one or more carbon blocks, and come equipped with one or more shunts or terminals.

How many parts does a carbon brush have?

A carbon brush may have one or more carbon blocks and one or more shunts or terminals. There are often multiple carbon brushes in a motor or generator. This is achieved by passing electrical current between the motor’s stationary and rotating wires.

Are carbon brushes necessary for a generator?

Without brushes, motors and generators could not conduct electricity — and thus, could not function. Service or replacement of your brushes may be required. Carbon brushes are one of the most critical components of motors and generators.

How does a carbon brush function?

A carbon brush works by passing electrical current between the motor’s stationary and rotating wires. It typically consists of one or more carbon blocks and one or more shunts or terminals.

Why was carbon preferred over copper for motor brushes?

Carbon eventually became the preferred motor brush material because of its high contact resistance, low friction, and ability to resist arcing. Although the first brushes were made of copper, carbon's unique properties made it a better choice for motor brushes.

What are the maximum surface speeds for Class A carbon brushes?

Class A carbon brushes, suitable for use on older, slower machines with maximum surface speeds of 4,000 feet per minute, are one of the first carbon brushes. This type of carbon brush is used in metal contacts and bases and is rarely seen in commutators because of the high friction it generates.