The principle for the armature was first developed by English scientist, Michael Faraday, when he made the discovery that if a loop of wire is moved up and down between the two poles of a magnet, a current of electricity moves through the wire. His discovery was improved upon to create something that would produce electric currents. The early AC transformer in the museum's outdoor exhibit works on a modified version of this early discovery. These types of generators produced a large amount of amperage (how quickly the electricity is moving) at a relatively low voltage (how much potential electricity there is).
An armature is made up of a coil of copper wire wound around an iron or steel core. The core is what remains outside the museum. This entire piece is placed in a magnetic field, which is produced by one or more permanent magnets. The armature is then rotated in the field by an outside force, which causes the coil to cut the lines of the magnetic field, just like in Faraday's early experiment. This action creates an alternating current of electricity within the coil.
The next step in this process is finding a way to harness the electricity generated from this process. Wire cannot be directly attached to the coil, because the constant spinning would cause them to wear and break. The solution was the addition of metal brushes, which are placed at the top and bottom of the armature so that the coil spins between them. The diagram below shows how electricity exits through the top brush to light the bulb that is wired to it, and the circuit is completed with the second wire and the bottom brush. Through this brush system, the electricity is harnessed, and ready to use!
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| Diagram of an AC generator. Gibson page 195. |
These types of electricity generating devices are most often used in large scale industrial operations, because they are able to produce a large amount of electricity. This type of generator utilizes the armature as a movable core, which maintains an unvarying voltage and prevents electricity from surging and lights from flickering.
Now, when I walk past the core, I not only know that it is not a piece of modern art, but I am more aware of how it works to produce electricity. I hope that this research is useful to our visitors, who want to know a little bit more about this artifact and how it works.
Tierney Dickinson
Summer Intern
Telluride Historical Museum
telluridemuseum.org
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Charles R. Gibson, The Romance of Modern Electricity: Describing in non-Technical Language What is Known About Electricity and Many of its Interesting Applications, (Philadelphia: J.B. Lippincott Company , 1906 ) http://books.google.com/books?id=p_sHAAAAMAAJ&printsec=frontcover&dq=The Romance of Modern Electricity&hl=en&sa=X&ei=Cvr_UfnFOpKCyAGHo4HIBg&ved=0CDoQ6AEwAA
