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The nature of armature mmf for a zero power factor lagging load in a 3-f alternator is
- a)magnetizing
- b)demagnetising
- c)neutral
- d)cross magnetizing
Correct answer is option 'B'. Can you explain this answer?
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Verified Answer
The nature of armature mmf for a zero power factor lagging load in a 3...
Correct Answer :- B
Explanation : The effect of armature reaction mmf is purely demagnetizing in zero pf lagging load condition. This can be explained in 2 methods :
In Zero power factor lagging load, the load current is lagging behind the excitation voltage by 90 degree.
Due to zero power factor lagging load, the current in phase “a” of armature winding will become maximum when the field poles have advanced by 90 degree in assumed counter-clockwise direction.
Most Upvoted Answer
The nature of armature mmf for a zero power factor lagging load in a 3...
Explanation:
In a 3-phase alternator, the armature winding produces a rotating magnetic field. This rotating magnetic field induces an electromotive force (emf) in the stator windings, which generates the armature mmf (magnetomotive force).
When a load is connected to the alternator, the power factor of the load determines the nature of the armature mmf.
Zero Power Factor Lagging Load:
A zero power factor lagging load means that the load is purely resistive, resulting in a lagging power factor of 0. In other words, the load does not have any reactive component.
Demagnetizing Nature of Armature MMF:
When a zero power factor lagging load is connected to the alternator, the armature mmf produced by the load is demagnetizing in nature. This means that the armature mmf acts in the opposite direction to the main magnetic field produced by the rotor.
Effects of Demagnetizing Armature MMF:
The demagnetizing armature mmf reduces the net magnetic field strength in the air gap of the alternator. This reduction in the magnetic field weakens the overall performance of the alternator.
Reasoning:
The demagnetizing nature of the armature mmf in a zero power factor lagging load is due to the fact that a purely resistive load does not produce any reactive component. Without any reactive component, the armature mmf cannot assist the main magnetic field and instead opposes it. This opposition demagnetizes the alternator and reduces its efficiency.
Therefore, the correct answer is option 'B' - demagnetizing.
In a 3-phase alternator, the armature winding produces a rotating magnetic field. This rotating magnetic field induces an electromotive force (emf) in the stator windings, which generates the armature mmf (magnetomotive force).
When a load is connected to the alternator, the power factor of the load determines the nature of the armature mmf.
Zero Power Factor Lagging Load:
A zero power factor lagging load means that the load is purely resistive, resulting in a lagging power factor of 0. In other words, the load does not have any reactive component.
Demagnetizing Nature of Armature MMF:
When a zero power factor lagging load is connected to the alternator, the armature mmf produced by the load is demagnetizing in nature. This means that the armature mmf acts in the opposite direction to the main magnetic field produced by the rotor.
Effects of Demagnetizing Armature MMF:
The demagnetizing armature mmf reduces the net magnetic field strength in the air gap of the alternator. This reduction in the magnetic field weakens the overall performance of the alternator.
Reasoning:
The demagnetizing nature of the armature mmf in a zero power factor lagging load is due to the fact that a purely resistive load does not produce any reactive component. Without any reactive component, the armature mmf cannot assist the main magnetic field and instead opposes it. This opposition demagnetizes the alternator and reduces its efficiency.
Therefore, the correct answer is option 'B' - demagnetizing.
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The nature of armature mmf for a zero power factor lagging load in a 3-f alternator isa)magnetizingb)demagnetisingc)neutrald)cross magnetizingCorrect answer is option 'B'. Can you explain this answer?
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