Power Generation:

Generators & Dynamos
Development and History of the component that made electricity first commercially feasible

Dynamos and Generators convert mechanical rotation into electric power.

Dynamo - a device that makes direct current electric power using electromagnetism. Also known as a Generator, however the term generator normally refers to an "alternator" which creates AC power. How it works.

Generator - normally this term is used to describe an alternator which creates AC power using electromagnetism.
How it works.

Generators, Dynamos, and Batteries are the three tools necessary to create/store substantial amounts of electricity for human use. Batteries may have been discovered as early as 248 BC. They simply use chemical reaction to make and store electricity. Scientists played with the battery afterwards for experiments and discovery of phenomena. It was the dynamo that radically changed electricity from a curiosity into a profitable, reliable technology.

1. How it Works
2. Brief History of Dynamos and Generators
3. Videos of generators

How it Works:

The Dynamo consists of 3 major components: the stator, the armature, and the commutator.

Brushes are part of the commutator, the brushes must conduct electricity as the keep contact with the rotating armature. The first brushes were actual wire "brushes" made of small wires. These wore out easily and they developed graphic blocks to do the same job.

The stator is a fixed structure that makes magnetic field, you can do this in a small dynamo using a permanent magnet. Large dynamos require an electromagnet.

The armature is made of coiled copper windings which rotate inside the magnetic field made by the stator. When the windings move, they cut through the lines of magnetic field. This creates pulses of electric power.

The commutator is needed to produce direct current. In direct current power flows in only one direction through a wire, the problem is that the rotating armature in a dynamo reverses current each half turn, so the commutator is a rotary switch that disconnects the power during the reversed current part of the cycle.

 

There are two ways of wiring a dynamo: series wound and shunt wound. See the diagrams to learn the difference.

Below, video of a small simple dynamo:

 

The Generator

This section is under construction.

 

A Brief History:

The generator evolved from work by Michael Faraday and Joseph Henry in the 1820s. Once these two inventors discovered and documented the phenomena of electromagnetic induction, it lead to experimentation by others in both Europe and North America.

1932 - Hippolyte Pixii (France) built the first dynamo using a commutator, his model created pulses of electricity separated by no current. He also by accident created the first alternator. He did not know what to do with the changing current, he concentrated on trying to eliminate the alternating current to get DC power, this led him to create the commutator.

1830s-1860s - The battery is still the most powerful way to supply electricity for the various experimentation going on in that period. Electricity was still not commercially viable. A battery powered electric train from Washington DC to Baltimore failed, proving a gross embarrassment to the new field of electricity. After millions of dollars wasted steam still proved to be a better power source. Electricity still needed to prove to be reliable and commercially viable.

1860 - Antonio Pacinotti- Created a dynamo that provided continuous DC power

1867 - Werner Von Siemens and Charles Wheatstone create a more powerful, more useful dynamo which used a self powered electromagnet in the stator instead of the weak permanent magnet.

1871 - Zenobe Gramme sparked the commercial revolution of electricity. He filled the magnetic field with an iron core which made a better path for magnetic flux. This increased the power of the dynamo to the point were it was usable for many commercial applications.

1870s - There was an explosion of new designs in dynamos, designs ranged a wild assortment, only a few stood out as being superior in efficiency.

1876 - Charles F. Brush (Ohio) developed the most efficient and reliable dynamo design ever to that point. His inventions was sold through the Telegraph Supply Company.

1877 - The Franklin Institute (Philadelphia) conducts test on dynamos from around the world. Publicity from this event spurs development by others like Elihu Thomson, Lord Kelvin, and Thomas Edison.

1878 - The Ganz Company begins to use AC generators in small commercial installations in Budapest.

1880 - Charles F. Brush had over 5000 arc lights in operation, representing 80 percent of all lamps world wide. The economic power of electrical age had begun.

1880-1886 - Alternating Current systems develop in Europe with Siemens, Sabastian Ferranti, Lucien Gaulard, and others. DC dynamos reign supreme in the lucrative American market, many are skeptical to invest in AC. AC generators were powerful, however the generator alone was not the biggest problem. Systems for control and distribution of AC power needed to be improved before it could compete with DC on a market.

1886 - In the North American Market inventors like William Stanley, George Westinghouse, Nikola Tesla, and Elihu Thomson develop their own AC systems and generator designs. Most of them used Siemens and Ferranti generators as their basis of study. William Stanley was quickly able to invent a better generator after being unsatisfied with the Siemens generator he used in his first experiment.

1886-1891 - Polyphase AC generators are developed by C.S. Bradly (US), August Haselwander (Germany), Mikhail Dolivo-Dobrovsky (Germany/Russia), Galileo Ferraris (Italy), and others. AC systems which include better control and powerful electric motors allow AC to compete.

1891 - Three-Phase AC power proves to be the best system for power generation and distribution at the International Electro-Technical Exhibition in Frankfurt.

The three-phase generator designed by Mikhail Dolivo-Dobrovsky used at the exhibition is seen at left.

1892 - Charles P. Steinmetz presents his paper to the AIEE on hysteresis. Steinmetz's understanding of the mathematics of AC power is published and helps revolutionize AC power system design, including large AC Generators.

1890s - Generator design is improved rapidly thanks to commercial sales and available money for research. Westinghouse, Siemens, Oerlikon, and General Electric develop the world's most powerful generators. Some generators still operate 115 years later. (Mechanicville, NY)

This page will be expanded over time.

Videos

 

Westinghouse Generator being constructed and tested (1905)

 

1895 Early powerful generators used at Folsom, CA

 

1891 Generator produced by Oerlikon for the International Electro-technical Exhibition

More videos to come in the future.

 

Other Related Topics: Gas Turbines, Transformers, Electromagnetism

 

Sources:
-The General Electric Story - by The Hall of History, Schenectady, NY 1989 Second Edition
-Wikipedia (Generators, Charles Brush)

Photos / Video:
-Copyright 2011 The Edison Tech Center. Shot on location at the Deutsches Museum, Munich
-Some generators photographed at the Edison Tech Center, Schenectady, NY
-Videos from the Edison Tech Center

 

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