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Dynamo is the original and old name for Electrical Generator. Dynamo consists of a stationary structure, called the Stator, which provides a constant Magnetic Field, and a set of Rotating Windings called the Armature which turn within that Field. The Commutator was needed to produce Direct Current. When a Loop of Wire rotates in a Magnetic Field, the potential induced in it reverses with each half turn, generating an Alternating Current. However, in the early days of Electric experimentation, Alternating Current generally had no known use. The Dynamo uses Rotating Coils of Wire and Magnetic Fields to convert mechanical rotation into a pulsing Direct Electric Current through Faraday's Law. The Commutator is a set of contacts mounted on the machine's Shaft, which reverses the connection of the Windings to the External Circuit when the Potential reverses, so instead of Alternating Current, a Pulsing Direct Current is produced.
History
Michael Faraday invented the 'Dynamo' or The First Laboratory models of Electric Generator in 1831. It consisted of a Copper Disk that rotated between the Poles of a Magnet. This was not a 'Dynamo' in technical sense as it did not use a Commutator. However, Faraday's Disk generated very low voltage because of its Single Current Path through the Magnetic Field. Faraday and others found that higher, more useful Voltages could be produced by Winding Multiple turns of Wire into a Coil. Wire Windings can conveniently produce any Voltage desired by changing the number of turns, so they have been a feature of all subsequent Generator Designs, requiring the Invention of the Commutator to produce Direct Current.
Development in the Invention of the Dynamo
Pixii's Dynamo - In 1832, Hippolyte Pixii, a French Instrument Maker built the first Dynamo based on Faraday's Principles. It used a Permanent Magnet which was rotated by a Crank. The Spinning Magnet was positioned so that its north and south poles passed by a piece of Iron wrapped with Wire. Pixii found that the Spinning Magnet produced a pulse of Current in the Wire each time a pole passed the Coil. However, the north and south poles of the Magnet induced Currents in opposite directions. To convert the alternating current to DC, Pixii invented a Commutator, a Split Metal Cylinder on the Shaft, with two springy Metal contacts that pressed against it. His Dynamo is known as the First Direct Current (D.C.) Dynamo.
Pacinotti Dynamo - Around 1860, an Italian Physics Professor created his own version of Dynamo. Pacinotti Dynamo replaced the Spinning Two-Pole Axial Coil with a Multi-Pole Toroidal one, which was created by wrapping an Iron Ring with a Continuous Winding, connected to the Commutator at many equally spaced points around the Ring; the Commutator being divided into many segments. This meant that some part of the Coil was continually passing by the Magnets, smoothing out the current. Pacinotti Dynamo solved the problem of earlier designs in which the Electric Current produced consisted of a series of "Spikes" or Pulses of Current separated by none at all, resulting in a low Average Power Output.
Siemens and Wheatstone Dynamo - Dr. Werner Siemens (German Inventor) and Charles Wheatstone (English Scientist) independently and simultaneously announced the First Practical Designs for a Dynamo. On January 17, 1867, announced to the Berlin academy a Dynamo-Electric Machine which employed a Self-Powering Electromagnetic Armature. On the same day that this Invention was announced to the Royal Society, Charles Wheatstone read a paper describing a similar design with the difference that in the Siemens design the Armature was in series with the Rotor, but in Wheatstone's design it was in parallel. The use of Electromagnets rather than permanent Magnets greatly increases the Power Output of a Dynamo and enabled High Power Generation for the first time. This Invention led directly to the first major Industrial uses of Electricity.
Gramme Ring Dynamo - Zénobe Gramme, a Belgian Electrical Engineer reinvented Pacinotti's design in 1871 when designing the first Commercial Power Plants, which operated in Paris in the 1870s. Gramme's Design had a better path for the Magnetic Flux, by filling the space occupied by the Magnetic Field with Heavy Iron Cores and minimizing the air gaps between the stationary and rotating parts. The Gramme Dynamo was the first machine to generate commercial quantities of Power for industry. Further improvements were made on the Gramme Ring, but the basic concept of a spinning endless Loop of Wire remains at the heart of all Modern Dynamos.
Brush Dynamo - During 1876 Charles F. Brush, a U.S. Inventor assembled his first Dynamo using a Horse-Drawn Treadmill to power it. He was issued a U.S. Patent #189997 - "Improvement in Magneto-Electric Machines" on April 24, 1877. Brush started with the basic Gramme Design where the Wire on the sides and interior of the Ring were outside the effective zone of the Field and too much heat was retained. To improve upon this design, he shaped the Ring Armature like a Disc rather than the Cylindrical Shape of the Gramme Armature. The Field Electromagnets were positioned on the sides of the Armature Disc rather than around the circumference. There were Four Electromagnets, two with North Pole Shoes and two with South Pole Shoes. The like Poles opposed each other, one on each side of the Disc Armature. In 1881 one of The Brush Electric Company Dynamos was reported to be; 89 inches long, 28 inches wide, and 36 inches in height, and weighing 4,800 pounds, and ran at a speed of about 700 revolutions per minute. It was believed to be the Largest Dynamo in the world at that time. Forty Arc Lights were fed by it, and it required 36 horse power.
Role of the Invention of the Dynamo in the Improvement of Human Life
