# How a hydro power plant work?

In this post I will talk about the working of hydro power plants. The working principle is simple, but there are more things behind a hydro power plant.

Working principle

It is used the Faraday’s law of induction, the variation of a magnetic field in a coil create a inducted voltage in it’s terminals.

$\varepsilon =-N\frac{d\phi }{dt}$

$\varepsilon$ is the induction voltage, $N$ is the turns number and $\frac{d\phi }{dt}$ is the magnetic flux variation in time. This equation shows that more turns and flux varying faster increase the induction voltage.

The generator

The water turn the turbine linked to the axis of a generator which is an electrical machine whose rotor has many permanent magnets. The stator has coils which receive the induction voltage.

The generator turbine is usually a Francis turbine. 60% of hydro power plants use this type of turbine, because they are very efficient and can operate with a flux from 10 to 700 $m^3/s$ and with a water height from 45 to 400 meters.

The green arrows show the way of the water.

The turbine’s blades are airfoils in a way that there is low pressure in one side and high pressure in another side and it is created a reaction force ($F_{LIFT}$). This blade has an unique format to have also an impulse force when the water hits the blade.

The blades in red assembled in the turbine.

The Transformer

The transformer linked in the stator’s terminals must be a step up to transmit electrical energy to long distances. Here is an example of step up transformer to hydro power plants.

To know more about transformers and your various types, click in the buttons below.

The dam

The dam is necessary to control the river’s water flux to hydro power plant. First must dig trenches to divert the river’s course. Then put the foundation and concrete. Must take out the trench after the dam is ready.

The dam must have a control gate and  a duct to conduce water to the turbine.