12-06-2014, 11:48 AM
SYNCRONOUS MACHINES
SYNCRONOUS MACHINES.ppt (Size: 919 KB / Downloads: 307)
Principle of Operation
The operation of a synchronous generator is based on Faraday's law of electromagnetic induction, and in an ac synchronous generator the generation of emf's is by relative motion of conductors and magnetic flux.
These machines can be used as either motors or generators but their predominant use is in generation.
There are a number of sources of energy used to turn the turbines:-
(a) Gas (b) Steam© Combined cycle (d) Nuclear(e) Hydro (f) Wind(g) Wave (h) Photovoltaic
Its characteristic feature is that the armature rotates through a stationary magnetic field, and the generated AC is brought to the load by means of slip rings and brushes.
The revolving-armature alternator is found only in alternators of small power rating and is not generally used. This is because a rotating armature requires slip rings and brushes to conduct the current from the armature to the load.
Single Phase Alternator
As the rotor (field) turns, its poles will induce AC voltages in the stator (armature) windings. Since one rotor pole is in the same position relative to a stator pole as any other rotor pole, both the stator poles are cut by equal amounts of magnetic lines of force at any time. As a result, the voltages induced in the two poles of the stator winding have the same amplitude or value at any given instant.