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The 1891 International Electrotechnical Exhibition was held between 16 May and 19 October on the disused site of the three former "Westbahnhöfe" (Western Railway Stations) in Frankfurt am Main. The exhibition featured the first long distance transmission of high-power, three-phase electric current, which was generated 175 km away at Lauffen am Neckar.As a result of this successful field trial, three-phase current became established for electrical transmission networks throughout the world.
The "Elektrotechnische Gesellschaft" (Electrotechnical Society) was founded in Frankfurt in 1881 with the aim of promoting electricity and, in particular, furthering research into its application for industry and technology. Three years later, some ten manufacturers of electrical equipment had set themselves up in the city. In around 1890, some of the enterprises were established which would later become major firms in Frankfurt: Hartmann & Braun, Staudt & Voigt (from 1891 Voigt & Haefner) and W Lahmeyer & Co (from 1893 Elektrizitäts-AG, previously W Lahmeyer & Co). And it was in Frankfurt that the "second industrial revolution" began to emerge – a revolution that would bring about fundamental changes similar to those created 100 years previously by the introduction of the steam engine to the world of work. In 1891, the German electrical industry was ready to demonstrate its capabilities to the world at the International Electrotechnical Exhibition. A site was chosen – that of the former western stations between the city and the new main station, which had been completed in 1888.
Prompted by the Paris "Exposition Universelle" (World Fair) of 1889, Leopold Sonnemann, publisher of the Frankfurter Zeitung newspaper, interested the Electrotechnical Society in the idea of an exhibition. The Society expressed an interest and started preparations in the same year. However, there was another consideration apart from the setting up of an international exhibition – Frankfurt had an urgent problem to solve. The construction of a central power station had been under discussion in the city’s political and technical committees since 1886. However, agreement had still to be reached over the type of current, and opinions were divided between direct current, alternating current and three-phase current. It fell to the exhibition to demonstrate a commercially viable method for the transmission of electricity. Three-phase current with a minimal loss of 25% would be transmitted at high voltage from Lauffen am Neckar to Frankfurt. This took centre stage at the exhibition and was evidenced in the large three-section entrance gate. The central section took the form of an arch bearing the inscription "Power Transmission Lauffen–Frankfurt 175 km." Rectangular panels flanked the arch: the one to the right carrying the name of the "Allgemeine Electricitätsgesellschaft" ("AEG" – General Electricity Company), which had been founded in 1887; the left-hand panel displayed the name of the "Maschinenfabrik Oerlikon" (Oerlikon Engineering Works). The entire entrance was illuminated with 1000 light bulbs and an electrically powered waterfall provided a further attraction. With 1,200,000 visitors from all over the world, the exhibition was an out-and-out success. The cost of a one-day entry ticket for an adult amounted to a considerable 15 marks.
As far as Germany was concerned, the International Electrotechnical Exhibition settled once and for all the question of the most economical means of transmitting electrical energy. When the exhibition closed, the power station at Lauffen continued in operation – providing electricity for the administrative capital, Heilbronn, thus making it the first place to be equipped with a power supply using three-phase AC. The name of the local power company (ZEAG) bears testimony to this event. The Frankfurt city council constructed its own power station near the harbour; yet another was built by a private company in the suburb of Bockenheim.
A hydraulic turbine at Lauffen powered a three-phase alternator with a revolving field. The alternator revolved at 150 revolutions per minute, and had a rotating field magnet with 32 poles. It was rated at 300 hp and had a terminal voltage of 55 volts. The frequency of the current was 40 Hz. Power from the alternator was stepped up to 8000 volts for transmission by oil-insulated transformers. Later tests were carried out with transmission voltage up to 25,000 volts (between phases).
The transmission line was erected with the assistance of the German Post Office and used about 60 tonnes of copper wire, 4 mm in diameter. At the exhibition, the voltage was stepped down by further oil-filled transformers and connected to motors and a motor-generator system for lamps.
Overall efficiency from turbine to load was an average of 75%, which resolved many doubts of the practicality of long-distance electric power transmission.
Electric power transmission is the bulk movement of electrical energy from a generating site, such as a power plant, to an electrical substation. The interconnected lines which facilitate this movement are known as a transmission network. This is distinct from the local wiring between high-voltage substations and customers, which is typically referred to as electric power distribution. The combined transmission and distribution network is part of electricity delivery, known as the "power grid" in North America, or just "the grid". In the United Kingdom, India, Tanzania, Myanmar, Malaysia and New Zealand, the network is known as the National Grid.
Three-phase electric power is a common method of alternating current electric power generation, transmission, and distribution. It is a type of polyphase system and is the most common method used by electrical grids worldwide to transfer power. It is also used to power large motors and other heavy loads.
Alternating current (AC) is an electric current which periodically reverses direction, in contrast to direct current (DC) which flows only in one direction. Alternating current is the form in which electric power is delivered to businesses and residences, and it is the form of electrical energy that consumers typically use when they plug kitchen appliances, televisions, fans and electric lamps into a wall socket. A common source of DC power is a battery cell in a flashlight. The abbreviations AC and DC are often used to mean simply alternating and direct, as when they modify current or voltage.
Mains electricity is the general-purpose alternating-current (AC) electric power supply. It is the form of electrical power that is delivered to homes and businesses, and it is the form of electrical power that consumers use when they plug items such as domestic appliances, televisions and electric lamps into wall outlets.
Electric power distribution is the final stage in the delivery of electric power; it carries electricity from the transmission system to individual consumers. Distribution substations connect to the transmission system and lower the transmission voltage to medium voltage ranging between 2 kV and 35 kV with the use of transformers. Primary distribution lines carry this medium voltage power to distribution transformers located near the customer's premises. Distribution transformers again lower the voltage to the utilization voltage used by lighting, industrial equipment or household appliances. Often several customers are supplied from one transformer through secondary distribution lines. Commercial and residential customers are connected to the secondary distribution lines through service drops. Customers demanding a much larger amount of power may be connected directly to the primary distribution level or the subtransmission level.
An alternator is an electrical generator that converts mechanical energy to electrical energy in the form of alternating current. For reasons of cost and simplicity, most alternators use a rotating magnetic field with a stationary armature. Occasionally, a linear alternator or a rotating armature with a stationary magnetic field is used. In principle, any AC electrical generator can be called an alternator, but usually the term refers to small rotating machines driven by automotive and other internal combustion engines.
The utility frequency, (power) line frequency or mains frequency is the nominal frequency of the oscillations of alternating current (AC) in a wide area synchronous grid transmitted from a power station to the end-user. In large parts of the world this is 50 Hz, although in the Americas and parts of Asia it is typically 60 Hz. Current usage by country or region is given in the list of mains electricity by country.
Power engineering, also called power systems engineering, is a subfield of electrical engineering that deals with the generation, transmission, distribution and utilization of electric power, and the electrical apparatus connected to such systems. Although much of the field is concerned with the problems of three-phase AC power – the standard for large-scale power transmission and distribution across the modern world – a significant fraction of the field is concerned with the conversion between AC and DC power and the development of specialized power systems such as those used in aircraft or for electric railway networks. Power engineering draws the majority of its theoretical base from electrical engineering.
Extra-low voltage (ELV) is an electricity supply voltage in a range which carries a low risk of dangerous electrical shock. There are various standards that define extra-low voltage. The International Electrotechnical Commission member organizations and the UK IET define an ELV device or circuit as one in which the electrical potential between conductor or electrical conductor and earth (ground) does not exceed 50 V a.c. or 120 V d.c..
This is an alphabetical list of articles pertaining specifically to electrical and electronics engineering. For a thematic list, please see List of electrical engineering topics. For a broad overview of engineering, see List of engineering topics. For biographies, see List of engineers.
Folsom Powerhouse State Historic Park is a historical site preserving an 1895 alternating current (AC) hydroelectric power station—one of the first in the United States.
Oskar von Miller was a German engineer and founder of the Deutsches Museum, a large museum of technology and science.
Mikhail Osipovich Dolivo-Dobrovolsky was a Polish-Russian engineer, electrician, and inventor.
The Ames Hydroelectric Generating Plant, constructed in 1890 near Ophir, Colorado, was the world's first commercial system to produce and transmit alternating current (AC) electricity for industrial use and one of the first AC hydro-electric plants ever constructed. It became operational in 1891 and was built by Westinghouse Electric around two of their large alternators. One was set up in the valley as a generator and driven by water. It was connected by a 2.6-mile (4.2 km) transmission line to the second alternator used as a motor up at the Gold King Mine to drive the mining operation. The facility has been changed and upgraded over the years but is still in operation. It is now on the List of IEEE Milestones.
An electric power system is a network of electrical components deployed to supply, transfer, and use electric power. An example of an electric power system is the grid that provides power to an extended area. An electrical grid power system can be broadly divided into the generators that supply the power, the transmission system that carries the power from the generating centres to the load centres, and the distribution system that feeds the power to nearby homes and industries. Smaller power systems are also found in industry, hospitals, commercial buildings and homes. The majority of these systems rely upon three-phase AC power—the standard for large-scale power transmission and distribution across the modern world. Specialised power systems that do not always rely upon three-phase AC power are found in aircraft, electric rail systems, ocean liners and automobiles.
Miesbach–Munich Power Transmission of 1882 was the first transmission of direct current (DC) electrical energy over a large distance.
Electric power transmission, the tools and means of moving electricity far from where it is generated, date back to the late 19th century. They include the movement of electricity in bulk and the delivery of electricity to individual customers ("distribution"). In the beginning, the two terms were used interchangeably.
Neptune Bank Power Station was a coal-fired power station situated on the River Tyne at Wallsend near Newcastle upon Tyne. Commissioned in 1901 by the Newcastle upon Tyne Electric Supply Company, the station was the first in the world to provide electricity for purposes other than domestic and street lighting. It was also the first in the world to generate electricity using three-phase electrical power distribution at a voltage of 5,500 volts.
René Thury was a Swiss pioneer in electrical engineering. He was known for his work with high voltage direct current electricity transmission and was known in the professional world as the "King of DC."
Single-phase generator is an alternating current electrical generator that produces a single, continuously alternating voltage. Single-phase generators can be used to generate power in single-phase electric power systems. However, polyphase generators are generally used to deliver power in three-phase distribution system and the current is converted to single-phase near the single-phase loads instead. Therefore, single-phase generators are found in applications that are most often used when the loads being driven are relatively light, and not connected to a three-phase distribution, for instance, portable engine-generators. Larger single-phase generators are also used in special applications such as single-phase traction power for railway electrification systems.