DC MACHINE ARMATURE REACTION PDF!
This set of DC Machines Multiple Choice Questions & Answers (MCQs) focuses on “Armature Reaction -1”. 1. In a DC machine, the form of. Jump to Armature reaction in a DC machine - Armature reaction in a DC machine. In a DC machine, the main field is produced by field coils. In both the generating and motoring modes, the armature carries current and a magnetic field is established, which is called the armature flux. The effect of armature flux on the main field is called the armature reaction.Terminology · Winding circuits. Armature Reaction: The effect of magnetic field set up by armature current on the . Compensating Windings: These are used for large direct current machines.
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Field poles are de-energised. Now, when a DC machine is running, both the fluxes flux due to the dc machine armature reaction conductors and flux due to the field winding will be present at a time.
Armature (electrical) - Wikipedia
The armature flux superimposes with the main field flux and, hence, disturbs the main field flux as shown in third figure the dc machine armature reaction above image. Sign In Get AccessScience for your institution.
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What is armature reaction in dc motor? - Quora
If the brushes were contacting commutator segments outside the neutral plane, they would short-circuit "live" coils and cause arcing and loss of power.
Armature reaction causes the neutral plane to shift in the direction of rotation, and if the brushes are in the neutral plane at no load, that is, when no armature current is flowing, they will not be in the neutral plane when armature current is flowing.
For this reason dc machine armature reaction is desirable to incorporate a corrective system into the generator design. These are two principal methods by which the effect of dc machine armature reaction reaction is overcome.
The first method dc machine armature reaction to shift the position of the brushes so that they are in the neutral plane when the generator is producing its normal load current. The brush-setting method is satisfactory in installations in which the generator operates under a fairly constant load.
The dc machine armature reaction flux superimposes with the main field flux and, hence, disturbs the main field flux as shown in third figure the of above image.
This effect is called as armature reaction in DC machines. The adverse effects of armature reaction: Armature reaction weakens the main flux. In case of a dc generatorweakening of the main flux reduces the generated voltage. Armature reaction distorts the main flux, hence the position of Dc machine armature reaction.
Brushes should be placed on the M.
Armature Reaction in DC Machine
Here also, the brushes are fixed at a position corresponding to its normal load and the mode dc machine armature reaction operation. Due to these limitations, this method is generally not preferred. Inter Pole The limitation of brush shift has led to the use of inter poles in almost all the medium and large sized DC machines.
Inter poles are long but narrow poles placed in the inter polar axis. They have the polarity of succeeding pole coming next in sequence of rotation in generator action and proceeding which has passed behind in rotation sequence pole in motor action.
The inter pole is designed to neutralize the armature reaction mmf dc machine armature reaction the inter polar axis.
Since inter poles are connected in series with armature, the change in direction of current in armature changes direction of inter pole.