How a hydroelectric plant works
A dam holds back a reservoir of water, hence accumulating potential energy. A penstock directs the water from the reservoir to the turbine, located below. The turbine converts the potential energy of the water into rotational kinetic energy. The generator connected thereto then converts the kinetic energy of the turbine into electricity, which is carried by the distribution network to final users.
A generator is made of two main components: a stator and a rotor. The stator is a steel structure on which are installed copper bars. The rotor in turn, is a steel fabrication, which supports the rim and the pole. The annular rim is a stack of steel laminations. The poles, in turn, are composed of a laminated steel core, surrounded by an insulated copper coil. The poles are installed on the rotor so that their magnetic polarity alternates from North to South for every pole.
The movement of the poles in front of the stator bars created an alternating polarity of the magnetic field exerted on them. This oscillating magnetic field generates an AC current in the stator bars, the induction principle discovered by Faraday induction.
When a conductor is subjected to a moving magnetic field, a voltage is induced in the conductor. The voltage induced in turn causes the flow of electrical current when the circuit is closed.For more information, consult the following links for instructive videos: