The relationship between magnetism and electrical current was discovered and documented by Oerstad in 1819. He found that if an electric current was caused to flow through a conductor that a magnetic field was produced around that conductor. In 1831, Michael Faraday discovered that if a conductor is moved through a magnetic field, an electrical voltage is induced in the conductor. The magnitude of this generated voltage is directly proportional to the strength of the magnetic field and the rate at which the conductor crosses the magnetic field. The induced voltage has a polarity that will oppose the change causing the induction – Lenz’s law. This natural phenomenon is known as Generator Action and is described today by Faraday’s Law of
Electro Magnetic Induction: (Vind = ∆Ø/∆t), where Vind = induced voltage, ∆Ø = change in flux density, ∆t = change in time All rotary generators built today use the basic principles of Generator Action.
THREE PHASE VOLTAGE
Three phase voltage is developed using the same principles as the development of single phase voltage. Three (3) coils are required positioned 120 electrical degrees apart. A rotating magnetic field induces voltage in the coils which when aggregated produce the familiar three phase voltage pattern.