Which material is commonly used in brushes? Explanation: Carbon is the most commonly used material in the manufacture of brushes. It is because carbon has high melting point, and is also less prone to high temperatures.
Which DC motor should never be run unloaded?
The torque in a dc series motor is inversely proportional to speed. From this it is seen that the speed increases as the torque decreases. At no load, when the torque is zero, the speed can increase to dangerous levels, which may result in the rotor disintegrating. DC series motor should never be started without load.
What is brush in dc motor?
They can either be graphite or precious metal brushes which have electrical motor connections. To supply power to the rotor we put in place a brush system and each of the brushes have a direct voltage symbol (+/-). The brushes are connected to the commutator bars which allows the current to flow into the winding.
Why are brushes made of graphite?
The introduction of graphite provided brushes that allowed a more uniform shift of current between commutator segments. Graphite carbon brushes also wear, sparing the commutator.