What are the functions of the brushes in a dc motor?
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They conduct current to stationary wires and moving parts
The brushes in a DC motor perform two important functions: electrical conduction and commutation.
Brushes act as the electrical contact points between the stationary part (stator) and the rotating part (rotor) of a DC motor. They are typically made of carbon or a carbon-graphite composite material. The primary function of the brushes is to provide a low-resistance path for the current to flow between the power source and the armature winding of the motor.
1. Electrical conduction: When the motor is energized, the brushes make contact with the commutator, which is a cylindrical metal segment mounted on the rotor. As the commutator rotates, it continuously switches the current direction flowing through the armature winding. The brushes maintain the electrical connection with the commutator segments, ensuring a consistent flow of current in the winding. This conduction allows the motor to generate the required magnetic field to produce torque and rotate.
2. Commutation: Another critical function of the brushes is commutation. The commutation process is responsible for reversing the direction of current flow in the armature winding at the appropriate time in order to maintain continuous rotation. As the commutator segments pass under the brushes, the brushes maintain electrical contact with the segments, allowing current to flow through the armature winding. The brushes act as switches, ensuring that the current direction is reversed when necessary to maintain the motor's rotation.
It's worth noting that the brushes in a DC motor are subject to wear and tear due to the friction and sparking that occurs during operation. This requires regular maintenance, including brush replacement, to ensure smooth and optimal motor performance.