Which of the following statements about armature reaction of alternator is NOT correct?

Question

Question

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SSC JE Electrical 16 Nov 2022 Shift 3 Official Paper

It increases the generated voltage and sparking at brushes reduces.
It reduces the generated voltage by distorting the main flux and it causes sparking at the brushes.
It depends on both load current and power factor.
When the generator is loaded, the armature carries the current; the armature current sets up its own magnetic field.

Answer 1

The correct answer is option 1):(It increases the generated voltage and sparking at brushes reduces.)

Concept:

The main field flux in the alternator is produced by the rotor field poles. When the alternator is loaded, the armature currents are set up which produce the armature flux. When the generator is loaded, the armature carries the current; the armature current sets up its own magnetic field.
This armature flux modifies the main flux in the air gap of the machine.
This action of armature flux is called armature reaction.
Armature reaction weakens the main flux. In the case of a dc generator, the weakening of the main flux reduces the generated voltage.
The effect of the armature reaction depends on the magnitude of armature current and on the power factor of the load.
So option 1 is wrong.The figure given below shows the resultant flux in the air gap of a dc generator