What is armature reaction in case of three phase alternator?

What is armature reaction in case of three phase alternator?

Armature reaction is defined as the effect of armature flux on the main flux produced by the field poles. Upon giving mechanical input and field excitation, the alternator generates the AC voltage by Faraday’s law of Electromagnetic induction.

What is the effect of armature reaction in alternator?

In other words, the effect of armature (stator) flux on the flux produced by the rotor field poles is called armature reaction. We already know that a current carrying conductor produces its own magnetic field, and this magnetic field affects the main magnetic field of the alternator.

What is armature reaction explain the effect of armature reaction on the terminal voltage of an alternator lagging power factor load draw the relevant phasor diagram?

Lagging Power Factor Load:

Sr. No. Loading Condition Effect of Armature Reaction
1) No Load No effect
2) Unity Power Factor Cross-magnetizing
3) Zero Power Factor Lagging Purely demagnetizing
4) Zero Power Factor Leading Purely magnetizing

What is armature reaction in alternators and what effect will it produce for pure capacitive and RL load?

Armature Reaction in Alternator When Load Power Factor is Zero Leading. 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°.

Which type of rotor is best for turbo alternator?

Smooth cylindrical type rotor is generally used for high speed alternators or turbo alternators.

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 are the main effects of armature reaction?

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 the effect of armature reaction on performance of synchronous machine?

This reverse effect is referred as Armature Reaction in Synchronous Generator.So, according to armature reaction, flux is reduced or distorted, the net emf induced is also affected and hence the performance of the machine degrades.

Which type of rotor is suitable for low speed alternators?

The salient pole type of rotor is generally used for slow speed machines having large diameters and relatively small axial lengths. The poles, in this case, are made of thick laminated steel sections riveted together and attached to a rotor with the help of joint.

What will an over excited operating alternator have?

An overexcited alternator always supplies lagging current to the connected load, which means that load is of lagging nature. Lagging load take active and reactive power from the supply or alternator. Therefore, reactive power flows outwards from an over-excited alternator.

What is armature reaction and its effect?

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 flux causes two effects on the main field flux. The armature reaction distorted the main field flux.

When does the armature reaction in an alternator start?

Now, when this alternator is connected to a balanced 3 phase load, a balanced three phase current starts flowing in the three phases of alternator. As the load is of unity power factor, this means that excitation voltage Ef and armature current Ia will be in phase.

What kind of armature winding is used in alternator?

Types of Armature Winding of Alternator. There are different types of armature winding used in alternator. The windings can be classified as. Single phase and poly phase armature winding. Concentrated winding and distributed winding. Half coiled and whole coiled winding. Single layer and double layer winding.

Where does the third phase winding of an alternator start?

Third or blue phase winding starts at slot no 3 and ends at slot no 12. The phase difference of induced emfs, in red phase and yellow, yellow phase and blue phase and blue phase and red phase winding respectively by 60 degrees, 60 degree and 240 degrees (electrical respectively).

Can a single phase armature winding be distributed?

Single phase armature winding can be either concentrated or distributed type. The concentrated winding is employed where the number of slots on the armature is equal to the number of poles in the machine. This armature winding of alternator gives maximum output voltage but not exactly sinusoidal.