Sage-Tips

How does armature reaction affect the output voltage of a dc generator?

Due to armature reaction, demagnetising effect comes into picture and generated emf decreses(at a fixed speed), so the terminal voltage. Due to armature reaction, commutation action is also affected.

What is 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 are two effects of armature reaction on the operation of a generator?

And the main field is produced by the magnetic poles. The armature flux causes two effects on the main field flux. The armature reaction distorted the main field flux. It reduces the magnitude of the main field flux.

How does the armature reaction affect the output voltage in a separately excited dc generator?

As the armature load current increases, the terminal voltage will decrease linearly. The terminal voltage of the separately excited DC generator would be expected to decrease in a linear manner due to the voltage drop across the armature circuit resistance.

How can an armature reaction be reduced in a DC generator?

1) The armature reaction causes the distortion in main field flux. This can be reduced if the reluctance of the path of the cross-magnetizing field is increased. The armature teeth and air gap at pole tips offer reluctance to armature flux. Thus by increasing length of air gap, the armature reaction effect is reduced.

What is armature reaction proportional to?

Armature reaction drop is the effect of a magnetic field on the distribution of the flux under main poles of a generator. This effect is known as armature reaction and is proportional to the current flowing in the armature coils.

Is armature reaction good or bad?

Due to the above two effects of armature mmf, there are many detrimental effects on the Electrical machine. Distortion of Main Field Flux gives rise to three detrimental effects: Rise in Iron Loss, Poor Commutation and Sparking in Carbon Brushes.

What is armature reaction How does it affect the operation of a de machine?

The armature reaction changes the distribution of the magnetic field, which affects the operation of the machine. 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.

What is armature reaction briefly describe the effect of power factor on the armature reaction of an alternator?

When an alternator supplies a load at unity power factor, the effect of armature reaction is partly cross magnetizing and partly distorting. The effect of armature reaction is demagnetizing, when an alternator supplies a load at lagging power factor.

How can the armature reaction be reduced in a DC machine?

What is the relationship of the armature voltage and field current in DC shunt generator?

This refers to DC Shunt Generator Magnetization Characteristics. Based on the experiment I conducted, the data shows that the armature voltage is directly proportional to the field current.

How do you compensate for the armature reaction?

The effect of armature reaction can be neutralized by use of compensating winding. It is always placed in series with armature winding. The armature ampere conductors under pole shoe must be equal to compensating winding ampere conductors which will compensate armature mmf perfectly.

What are the adverse effects of armature reactions on DC generators?

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 an armature reaction in a DC machine?

In a DC machine, two kinds of magnetic fluxes are present; ‘armature flux’ and ‘main field flux’. The effect of armature flux on the main field flux is called as armature reaction.

What is armature reaction in alternator?

Armature reaction is the effect of magnetic flux produced by the armature current on the distribution of flux under the main poles of a DC generator. The armature flux produces two effects: We can also see this armature reaction effect in an alternator.

What is the effect of armature reaction in 2 pole generator?

Due to the effect of armature reaction in a 2 pole DC Generator, the brush axis will give a lead of θ, so as to lie along the new MNA axis. Now consider the conductors lying within the angles AOB = COD = 2θ at the top and bottom of the armature. They carry the current such that the flux produced will flow from right to left.