What is meant by shaft and commutator in the armature?

Answer 1

"What is meant by shaft and commutator in the armature?"

While the question may contain a typo, I think it still would be helpful to better define the terms in your question.

An armature is an electromagnet that interacts with a constant magnetic field from the "field" circuit. So if your question is asking if the shaft and commutator are in the armature, that is not correct. The armature is generally regarded as the wire windings that make up the electromagnet.

A commutator is found in DC machines and is essentially just a mechanical rectifier. There are many armature winding coils wrapped around the shaft of a DC machine, and each coil is generally connected to two commutator plates.

When operating as a motor, the DC source voltage is applied to the armature coils such that the armature's magnetic field tries to line up with the constant magnetic field from the field circuit. The commutator switches over the source voltage to the correct armature coil such that the armature magnetic field is always trying to line up with the field circuit (thus we have continuous motion).

When operating as a DC generator, a sinusoidal voltage is induced on each of the armature windings as the generator spins. The commutator's job is to switch the coils such that the output voltage is somewhat constant. Generally, the commutator is connected to a coil when it is near the peak of its sinusoidal voltage and then switches to the next coil that is near its peak voltage.

Finally, the shaft is the spinning object that embodies the mechanical power of an electric machine. It should be attached to low-loss bearings to help increase machine efficiency. As a motor, the shaft outputs mechanical power to do some sort of useful task (such as running a fan or compressor, etc). As a generator, the shaft is the input for mechanical power. Some mechanical power source has to move the shaft so that electric power can be used from the generator.

I hope that helps you understand the terms given in your question.

Answer 2

the armature is the moving part of a motor or generator.

the shaft is the central rod on which the armature rotates.

the commutator is the part that transfers the power too or from the moving windings in the armature to the static part of the motor or generator (either too or from the electricity supply).

Answer 3

Commutator:
http://en.wikipedia.org/wiki/Commutator_(electric)

Armature:
http://en.wikipedia.org/wiki/Armature_%28electrical_engineering%29

You should know what a "shaft" is.