how self excited DC generator initially starts. please explain in ur own language.
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How DC Self Generator Start:
Since initially, when generator is off, there is no volatge. Now when generator starts, the initial emf induced is zero. Thus with no emf, no current is given to field winding. So no flux. And thus generator will not induce any voltage.
But practically, generator generates emf. This is because each magnetic material has a property to store some residual flux. This can be understood by B-H curve.
So initially , some residual flux is present. When rotor (armature ) is rotated , it cuts that small residual flux. Due to this, a small voltage is induced as output. This small voltage can be fed back to the same field winding . Thus more flux, and so more emf is induced as output. Flux will rise till the saturation is achieved. At saturation flux, rated emf is achieved as output of generator.
If initially there is no residual flux , then field flashing is done, so that some residual flux is stored in the core of field winding.
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Since initially, when generator is off, there is no volatge. Now when generator starts, the initial emf induced is zero. Thus with no emf, no current is given to field winding. So no flux. And thus generator will not induce any voltage.
But practically, generator generates emf. This is because each magnetic material has a property to store some residual flux. This can be understood by B-H curve.
So initially , some residual flux is present. When rotor (armature ) is rotated , it cuts that small residual flux. Due to this, a small voltage is induced as output. This small voltage can be fed back to the same field winding . Thus more flux, and so more emf is induced as output. Flux will rise till the saturation is achieved. At saturation flux, rated emf is achieved as output of generator.
But practically, generator generates emf. This is because each magnetic material has a property to store some residual flux. This can be understood by B-H curve.
So initially , some residual flux is present. When rotor (armature ) is rotated , it cuts that small residual flux. Due to this, a small voltage is induced as output. This small voltage can be fed back to the same field winding . Thus more flux, and so more emf is induced as output. Flux will rise till the saturation is achieved. At saturation flux, rated emf is achieved as output of generator.
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