Armature reaction in alternator

My question is, why is BS is perpendicular to IA. If excitation of one alternator is increased without changing its steam supply, then. This stator magnetic field distorts the original rotor magnetic field, changing the resulting phase vo ltage. A Hz alternator will run at the greatest possible speed if it is wound for

Uploader: Mugor
Date Added: 28 May 2009
File Size: 45.87 Mb
Operating Systems: Windows NT/2000/XP/2003/2003/7/8/10 MacOS 10/X
Downloads: 27174
Price: Free* [*Free Regsitration Required]





This stator magnetic field distorts the original rotor magnetic field, changing the resulting phase vo ltage. Since this power comes from excitation of synchronous machine, the net reactive power gets reduced in the generator.

Post as a guest Name. The main disadvantage of using short-pitch winding in alternators is that it. AlternatorElectrical Machines.

Three-phase alternators are invariably Y-connected because. If excitation of one alternator is increased without changing its steam supply, then. As soon as current starts flowing through the armature conductor there is one reverse effect of this current on the main field flux of the alternator or synchronous generator.

Leave a Reply Cancel reply Your email address will not be published. Due to armature reaction, flux is reduced or distorted, the net emf induced is also affected and hence the performance of the machine degrades. Before connecting them in parallel, you would. Leave a Reply Cancel reply Your email address will not be published.

This armature flux reacts with the main pole flux, causing the resultant flux to become either less than or more than the original main field flux. It should be perpendicular to the plane the coil is on, in other words, it should be perpendicular to EA applying the right hand rule. This site uses Akismet to reduce spam. As the load is of unity power factor, this means that excitation voltage E f and armature current I a will be in phase. The direction of rotation of the conductors is alternatr anticlockwise with respect to the rotor poles.

When the generator supplies a load at leading power factor the armature reaction is partly magnetising and partly cross-magnetising. As the field is excited by DC, the main field flux is constant in respect to field magnets, but it alrernator be alternating in respect of armature as there is a relative motion between field and armature in the alternator. Thus to summarize, the effect of armature reaction mmf on main filed mmf of alternator is tabulated below. Coil EA is shown where in your diagrams?

Armature Reaction in Alternator or Synchronous Machine | Electrical Concepts

The filed winding on rotor is fed by DC source for setting up working or main filed mmf. The dc generators and dc motors have the same general construction.

Due to relative motion between armature conductors and the main field, an emf is induced in the armature windings whose magnitude depends upon the relative speed and as well as the reactioj flux. Of the following conditions, the one which does not have to be met by alternators working in parallel is.

But we know theoretically that emf induced in the armature is due to changing main field flux, linked with the armature conductor. As the term armature is used here, it means the part of the generator that contains the polyphase winding.

Effects of Armature Reaction

The armature reaction mmf can be resolved into two components: The current is coming armaturf of the page above and going into the page under. Since the armature is on open-circuit, there is no stator current and the flux due to rotor current is distributed symmetrically in the air-gap as shown in Fig.

They deteriorate the performance of the machine. The phasor diagram is shown below.

Armature Reaction of Alternator at Lagging Zero Power Factor At lagging zero armatjre power factor, the armature current lags by 90 o to induced emf in the armature. According to Faraday's law of electromagnetic induction there would be an emf induced in the armature. The effect of armature flux on the flux produced by field ampere turns i. Subscribe to our mailing list and get interesting stuff and updates to your email inbox. If the alternator is loaded with a load of zero power factor leading.

1 thoughts on “Armature reaction in alternator

Leave a Reply

Your email address will not be published. Required fields are marked *