What is armature reaction of alternator?

What is armature reaction of alternator?

Armature reaction in alternator is defined as the effect of armature flux on the main flux produced by the field poles. When there exists a relative motion between the magnetic flux and armature winding, the armature conductor cuts the field flux. Hence there will be a change in flux linkage in the conductor.

What is armature reaction in case of three phase alternator?

This reverse effect is referred as armature reaction in alternator or synchronous generator. In other words, the effect of armature (stator) flux on the flux produced by the rotor field poles is called armature reaction.

What is the effect of armature reaction when the alternator is connected to 0.8 PF lagging?

Effect of armature reaction in alternator: At lagging power factor load, the armature reaction is partly demagnetising and partly cross-magnetising; At zero power factor lagging load, it is purely demagnetising and the induced emf will get decreased.

What is the effect of power factor on armature reaction?

Effect of Load Power Factor on Armature Reaction Case 3 – Zero Leading Power Factor Load− When the load power factor is zero leading i.e. pure capacitive load, then the armature reaction strengthens the main field flux and not to distort it. This causes an increase in the generated voltage.

How do you reduce the armature reaction in an alternator?

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 reactance?

[′är·mə‚chər ‚rē′ak·təns] (electromagnetism) The inductive reactance due to the flux produced by the armature current and enclosed by the conductors in the armature slots and the end connections.

What is the effect of armature reaction of an alternator at 0.9 pf lagging?

The EMF will get decreased due to demagnetization.

What is the function of damper winding in alternator?

Damper winding in an alternator is also known as squirrel-cage winding. This winding is located inside the slotted pole shoes of the alternator. Prevents hunting (momentarily speed fluctuations) in the alternator, Increases the transient stability.

What is armature reaction and what are the effect of armature reaction?

Definition: The armature reaction simply shows the effect of armature field on the main field. In other words, the armature reaction represents the impact of the armature flux on the main field flux. The armature field is produced by the armature conductors when current flows through them.

What is armature reaction and how it can be reduced?

Explanation: Armature reaction can be reduced with the help of compensating winding. To neutralize the cross-magnetizing effect of armature reaction in a DC machine, a compensating winding is used. The compensating windings consist of a series of coils embedded in slots of the pole faces.

What are the types of armature reaction?

Types of Armature-Reaction

  • Demagnetization of the stator field.
  • The cross magnetization of the stator field.

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.

What is the effect of armature reaction on capacitive load in alternator?

When a pure capacitive load (zero p.f. leading) is connected across the terminals of the alternator, the current in armature windings will lead the induced e.m.f. by 90°. Fig: 1 (d) Obviously, the effect of armature reaction will be the reverse that for pure inductive load.

What is armature reaction in generator?

Armature reaction refers to the influence of the armature flux on the field flux in the air gap when the stator windings are connected across a load. If F f is the field mmf in the generator under no load, then the generated voltage E g must lag F f by 90 o

What are the fundamental principles of alternator?

Fundamental Principles of A.C. Machines: E.M.F. equation of an elementary alternator, Single & three Phase, relation between speed & frequency, factors affecting the induced e.m.f., full pitch & fractional pitch windings, winding factors, armature reaction, the rotating field leakage reactance. Concept of time phasor & space phasor.

When an alternator supplies a load at the intermediate power factor?

When an alternator supplies a load at the intermediate power factor, the effect of armature reaction is partly distorting and partly demagnetizing. The effects of armature reaction may cause the generated emf to vary.