Turbine-generator unit

The role of the turbine to transform the energy of the water, steam or the wind into mechanical energy so as to turn a generator. The generator, in turn, converts the mechanical energy into electrical energy. In the case of hydro, called turbine generator turbine and generator that work together.

The turbine rotates due to the movement of the water.

Water reaches the turbine generator by the penstock that carries the spiral casing (pipe spiral). It rotates the blades and then moves towards the axis of the turbine for flow into the vacuum underneath. The mechanical energy produced by the strong pressure exerted by the water on the turbine is transmitted to the generator that transforms it into electrical energy.

Driven by the turbine, the generator generates an alternating current.

The generator, coupled to the turbine shaft by layer, is formed of a movable part, called a rotor, and a fixed portion, called stator. The outer wall of the rotor is composed of electromagnets, while the inner wall of the stator winding consists of a copper rod. As the rotor turns within the stator, the electrons present in the copper bars "vibrate". The movement of electrons creates an electric current, just as in Faraday's experiment , conducted in 1831 and on the electromagnetic induction, but a very large scale.

Establishment of a Kaplan turbine

The turbines have a constant rotational speed.

It is imperative that all generating units of a network are strictly synchronized, ie they maintain exactly their speed. Why? To produce electric power quality.Devices that consume electricity are designed according to an alternating current whose frequency is accurate. This frequency depends on the rotational speed of the group, that is to say the number of times per second that the magnets of the rotor pass in front of the bars of the stator conductive metal. This frequency is expressed in cycles per second or hertz (Hz), named after the German physicist Heinrich Hertz, who demonstrated the existence of radio waves.

In North America, the standard cycle of alternating current is 60 times per second, while in Europe it is 50 times per second. This means that a clock which the engine is designed to run at 60 Hz will fall behind if it was plugged into a European outlet, because it would work more slowly.

Turbine rotors in La Grande-3
at La Grande-3, the rotors consist of 32 pairs of electromagnets. They must therefore 112.5 rpm to provide an alternating current of 60 Hz

Here the calculation was done by the engineers:

32 pairs of electromagnets × 112.5 rpm 
= 3600 rpm or 60 revolutions per second (60 Hz)