Armature Reaction is the effect of magnetic flux set up by armature current The brushes of the DC machines are always placed in this axis, and hence this axis. armature reaction mmf gets added at this tip leading to considerable amount In some small d.c. machines the brushes are shifted from the position of the mag-. Commutation problem is not the only problem in DC machines. At heavy loads, the cross magnetizing armature reaction may cause very high.

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And the GNA divides the armature core into two equal parts. Electromagnetic components Electric motors. The tip of the pole from where the armature conductors come into influence is called leading tip and the other tip opposite in direction to it will be the trailing tip.

So, the neutral zone has much higher band of angle in which it can exist at various load current. Now flux is produced due to the armature current and this flux always going to in this direction whatever may the position be of will resultant voltage being induced in the coil.

Connects Facebook Armatrue Videos. Armature reaction drop is the effect of a magnetic field on the distribution of the flux under main poles of a generator. The second role is to generate an electromotive force EMF. So orthogonal to that only will be the neutral zone. On another side also have a flux distribution or field distribution so a flux lines is in form of ring by the right hand rule and in anti-clockwise direction. So, for a given rating of machine, a wave winding is more suitable for large currents and low voltages.

The magnetic neutral axis or plane is perpendicular to the axis of the magnetic flux. Now let us look at the effect of this armature reaction.

Fig 11 Commutating poles to reduced armature reaction Let the commutator which is placed and also have the brushes in the neutral zone.

Due to motion of coil, current induced in the conductors of the coil which flow through the brushes and to the external circuit. Compensating winding consists of conductors embedded in the pole face that run parallel to the shaft and carry reaaction armature current in a direction opposite to the direction of current in the armature conductors under that pole arc.


Inter poles are long but narrow poles placed in the inter polar axis. Thus in this case compensation windings are installed in slots of the poles faces of main field poles.

These windings are connected in series with the armature winding in such a position that the current flowing in the compensation winding is exactly opposite to the current flowing in the armature winding at the same time. In this condition, only the MMF of the main poles exists in the generator.

What is Leading and Trailing Pole tip? Newer Post Older Post Home.

Fig 8 Resultant flux due to interaction between two fluxes Now the flux created by armature current is in the upward direction and the direction of north-south pole flux is right angle to this flux.

This flash over may spread to the neighboring commutator segments, leading ultimately to a complete fire over the commutator surface from brush to brush. In a DC machine, two sources of magnetic fluxes are present; ‘armature flux’ and ‘main field flux’. In a DC machinetwo kinds of magnetic fluxes are present; ‘armature flux’ and ‘main field flux’.

The orthogonal plane is supposed to be Fig 7 Main d.c.maachines flux and flux due to armature current the neutral zone where no induced zrmature and thereby no induced current because at this point flux is equal to zero in There are two fluxes present in DC machine, the flux due to that direction.

The magnetic neutral axis MNA is the axis drawn perpendicular to the mean direction of the flux passing through the centre of the armature. The brush-setting method is the most common means of correcting for armature reaction in small generators those producing approximately W or less.

Armature Reaction in a DC Generator – its Effect – Circuit Globe

In the armature, an electromotive force is created by the relative motion of the armature and the field. Field created by conductor will distort the main field. The MNA is continuously shifted with the resultant flux.

In other projects Wikimedia Commons. The following figure shows: Circuit Globe All about Electrical and Electronics. Coilgun Railgun Superconducting machine. The primary duty of inter polar winding is to improve the commutation process, and that of the compensating winding is to compensate for the increase or decrease in the net air gap flux i. The armature flux is produced by the current induces in the armature conductors while the field pole flux is induced because of the main field poles.


In electrical engineeringd.c.machinds armature is the power-producing component of an electric machine. Would you like to know more about DC Generator?

Recieve free updates Via Email! Inter polar windings are always kept in series with armature, so inter polar winding carries the armature current; therefore works satisfactorily reacfion of load, the direction of rotation or the mode of operation.

Armature (electrical)

As shown in Fig. AC motor DC motor. This problem is more acute while the load is decreasing in generating action and increasing in motor action as then, the induced e.

Hence, the conductor on both the sides combines their MMF in such a way so that their flux goes downward direction. Inter polar winding and compensating windings are connected in series with the armature winding but on the opposite sides with respect to armature.

So in flows from this commutated pole windings. Overall flux is less than the field flux because saturation occur at the pole tip B of the field pole due to higher field flux, thus increase in the flux at pole tip B armayure less than the decrease in the flux at pole tip A.

The armature reaction simply shows the effect of armature field on the main field. Similarly, the right-hand side conductors carry current, and their direction goes out of the paper shown by dots inside the circle. And this armature flux which is created due to the reactance eraction the coil because of the coil is inductive in nature armature current flowing in the conductor is called as it is trying to suddenly break current in the coil, a huge spark armature reaction which is shown in Fig.

The pole piece of a permanent magnet or electromagnet and the moving, iron part of a solenoidespecially if reaciton latter acts as a switch or relaymay also be referred to as armatures.

Armature Reaction in DC machines

You enjoy this post: Brushes are always placed along the MNA because reversal of current in the armzture conductors takes place along this axis. So this amplitude keeps varying then the resultant could be in any direction depending upon the amount of load current as shown in Fig.

So, the neutral zone can set at orthogonal to the main flux.

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