What is the commutation process?

Commutation in DC machines is the process by which the reversal of current takes place. In DC generator this process is used to convert the induced AC in the conductors to a DC output. In DC motors commutation is used to reverse the directions of DC current before being applied to the coils of the motor.

How does armature reaction affect commutation?

The armature reaction causes shifting the magnetic neutral axis. Therefore there will be some flux density at brush axis which produces emf in the coil undergoing commutation. This will lead to delayed commutation. Thus the armature reaction at brush axis must be neutralized.

What do you mean by armature reaction and commutation how these can be improved?

The armature reaction creates a flux in the neutral zone and due to this flux, a small voltage is induced in the commutating coil. Therefore, by shifting the brushes to the new MNA, the sparkless commutation can be obtained.

What is commutation process and armature reaction in a 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.

What are the three stages in the commutation process?

There are 3 methods to obtain Sparkless commutation: Resistive commutation. Voltage commutation. Compensating commutation.

What is Armeture reaction?

Armature reaction is the effect on the main field flux of that flux set up by the currents in the armature winding. The effect is the same for both lap- and wave-wound machines.

What is commutation process and method of improving commutation?

To make the commutation satisfactory we have to make sure that the current flowing through the coil completely reversed during the commutation period attains its full value. There are three main methods of improving commutation. These are. Resistance commutation. E.M.F. commutation.

What are the steps for effective commutation?

Methods of Improving Commutation

  • Resistance Commutation.
  • Voltage Commutation.
  • Brush Shift.
  • Commutating Poles or Interpoles.
  • Compensating Windings.

What is commutation process in SCR?

What is Commutation of SCR? Commutation of SCR is defined as the process of turning off an SCR / thyristor. It is the process by which an SCR or thyristor is brought to OFF state from ON state. We know that, an SCR is turned on by applying a gate signal to a forward biased SCR.

How does armature reaction occur?

The current flowing through the armature conductors creates a magnetic field, which is called as armature flux. This armature flux distorts and weakens the magnetic flux produced by the main poles. This effect of armature flux on the main flux is known as armature reaction.

What is a commutator and what does it do?

A commutator is a rotary electrical switch that periodically reverses the current between the rotor and the external circuit. The commutator was discovered by William Ritchie and Hippolyte Pixii in 1832. Commutators are used in DC machines (DC motors and DC generators) universal motors.