Additionally, at the same time that the Francis turbine was purchased, an alternator was acquired. In these documents, found in the municipal historical archive, you can see the budget dated August 8, 1919, of two machines, an A.E.G. type E.S.D, and a three-phase motor brand A.E.G. Berlin type, which is what was finally bought and installed in the mill. At the beginning of the century, the production of electrical energy was in private hands. It was not until 1944 that a national electricity company was created. Although can not assure exactly the exact date of start of use of all this machinery, we can say with certainty that at the beginning of the 20th century the mill was modernized with several machines.
On the other hand, the improvement of the production performance and the use of the canal's water, allowed considering the production of electricity for the consumption of individuals. This survey carried out by the owners of the mill to individuals from the surrounding farmhouses and which served to probe the volume of electricity that would need to be produced, is another evidence of this entire process of industrialization and modernization.
7. ALTERNATOR OPERATION
An alternator is a type of motor machine that converts mechanical energy to electrical energy in the form of alternating current, through a phenomenon known as electromagnetic induction which says that: “a conductor moving relative to a magnetic field develops an electromotive force in it”. Faraday's law is a basic law that predicts how a magnetic field will interact with an electric circuit to produce an electromotive force. For reasons of cost and simplicity, most alternators use a rotating magnetic field with a stationary armature.
The rotor, one of the parts of the alternator, is an electromagnet, which is usually driven by a turbine. The magnetic field rotates with the rotor at the same speed. The rotating magnetic flux from the rotor intersects the winding of the stator that is placed around the rotor. This generates an alternating electromotive force in the winding, and this generates an alternating current when connected to a consumption.
8. MAIN PARTS OF AN ALTERNATOR
An alternator has the following three main parts: stator, rotor and the air gap.
Stator: or inductor, is a stationary and external part of the machine and is made of very thin sheets of silicon steel. It is a cylindrical hollow piece that surrounds the rotor, which supports the different components that make up the machine. It is separated from the rotor by the air gap. It has a few pair of poles formed by a winding around a core of soft ferromagnetic material.
Rotor: is a rotary and cylindrical part of the machine assembled on a movable shaft. Located inside the stator, supported by bearings (to avoid friction as much as possible and, consequently, a reduction in mechanical performance).
The one used in hydro generators is the Salient Pole Type Rotor. The number of poles are about 6 to 40 so it is rotated with low speed.
Air gap: it is the space that remains between the stator and the rotor, and allows the free rotation of the rotor.
Both the stator and the rotor contain electrical coils or circuits. So we can say that an alternator contains two electrical circuits linked by a magnetic circuit.