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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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In operation of DC Generator there is a flux between north-south poles and there is a coil in armature. When the machine or motor is used as a motor, this EMF opposes the armature current, and the armature converts electrical power to mechanical power in the form of torqueand transfers it via the shaft.

Armature (electrical) – Wikipedia

Thus the compensating winding produces flux, which is completely opposite and equal in magnitude to the armature flux, hence both cancel the effect of each other and thus armature reaction is completely neutralized.

Would you like to know more about DC Generator? Enter the email address you signed up with and we’ll email you a reset link. Now, there is a current in the previous loading direction because all this add up inside the core this produce effect diagram as shown in Fig. If the brushes remain at their previous positions, then back emf in case of motor or generated e.

This will reduce the induced voltage in generator and would increase the speed reaxtion motor. The distortion increases the density of the flux in the upper pole tip of N-pole and the lower pole tip of the south pole.


In flows through the conductor is shown in Fig. Doubly-fed Linear Servomotor Stepper Traction. The word d.c.mcahines was first used in its electrical sense, i. The north-south poles and conductors are in circular armature.

In other words, the armature d.c.machhines represents the impact of the armature flux on the main field flux. The direction of current remains same in all the conductors which lying under one pole. The armature reaction simply shows the effect of armature field on the main field. The effects of the armature flux can be offset by adding a compensating winding to the main poles, or in some machines adding intermediate magnetic poles, connected in the armature circuit.

The commutating poles are connected in series with the armature winding, but in such a design that they cancel the effect of reactjon conductor flux and hence we have left only the main field flux. Aluminum armature wiring is lighter and less expensive than copper.

The neutral plane is the position where the armature windings are moving parallel to the magnetic flux d.c.madhines, that is why an axis lying in this plane is called as magnetic neutral axis MNA. And the main field is produced by the magnetic poles. This field is at right angles to the generator field and is called cross magnetization of the armature. The direction of current induces in the conductor is ramature by the Fleming right-hand rule. Armature reaction drop is the effect of a magnetic field on the distribution of the flux under main poles of a generator.

Although distinctly separate these two sets of terminology are frequently used interchangeably or in combinations that include one mechanical term and one electrical term.

This topic is focused on one particular aspect of DC Generator. Compensating windings major drawbacks: This shifting of neutral axis is a continuous process, as the load varies continuously so the neutral axis as well and the brushes never coincide with neutral axis, hence good commutation is unachievable. The above problems are solved by use rreaction compensating winding. Power Factor Correction Equipment: And the negative terminal brush is connected to winding which is wound over There are many problems like high circulating current, poor this small pole and it is connected to negative terminal.


Now the machine has two fluxes, i. And the direction of flux generates in rraction conductors is given by the cork-screw rule. The orthogonal plane is supposed to be Fig 7 Main pole flux and flux due to armature current the neutral zone where no induced voltage and thereby no induced current because at this point flux is equal to zero in There are two fluxes present in DC machine, aramture flux due to that direction.

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.

Armature Reaction in DC Machine

In a “wave” winding, there are only two paths, and there are as many coils in series as half the number of poles. AC asynchronous induction IM. When the field flux enters into the armature, they may get distorted. This is because commutation occurs at the coils located on the brushes only, and the coil undergoing commutation comes under the influence of the alternate pole changes its location from north to south pole or vice versa.

In an induction generatorgenerated power is drawn from the stator.