What do brushes do in a DC generator?

In dc motors, the carbon brush makes sure the commutation process remains free from sparks. This contact is a sliding contact capable of transmitting electric current from static to the rotating part of a generator or electric motor. A single or several carbon blocks composes a brush.

What are the effects of armature reaction in DC generator?

The adverse effects of armature reaction: Armature reaction weakens the main flux. In case of a dc generator, weakening of the main flux reduces the generated voltage. Armature reaction distorts the main flux, hence the position of M.N.A. gets shifted (M.N.A. is perpendicular to the flux lines of main field flux).

What is the effect of communication in DC generator?

The commutation in DC machine or more specifically commutation in DC generator is the process in which generated alternating current in the armature winding of a dc machine is converted into direct current after going through the commutator and the stationary brushes.

Why brushes are kept at magnetic neutral axis?

It turns out that, these points lie along the Magnetic Neutral Axis (MNA), as the name suggests has magnetic neutrality along that axis. As net magnetic field along MNA is zero, hence no emf will be induced. So that’s where one must position the brushes.

What is the purpose of the brushes?

A brush is a device which conducts current between stationary wires and moving parts, most commonly in a rotating shaft. Typical applications include electricmotors, alternators and electric generators.

What is the purpose of brushes in a DC motor?

The function of the brushes is to conduct electricity to the individual segments as they rotate from brush to brush. This allows the motor to turn in one direction at a speed determined by the number of windings in the armature.

What is the effect of armature coils at points where brushes are located?

magnetically neutral region
What is the effect of armature coils at points where brushes are located? Explanation: Brushes are at magnetically neutral region hence, induced emf due to armature coils at brushes will be equal to zero.

What is the main effect of armature reaction?

Armature reaction has two undesirable effects: First, it distorts the main field. Secondly, it reduces the main field flux or both. When the main field is distorted, then there will be a cross magnetizing effect.

What do the brushes do in a DC motor?

Why is the brush shifting method not employed in practical commutation?

Why brushes shifting method is not employed in practical commutation? Explanation: Brushes are located at GNA’s, a small voltage is induced in the commutating coil. It could be partially remedied by shifting the brushes towards MNA but that causes direct demagnetization and is therefore not employed in practice.