Electrical engineering

Electrical engineering is an engineering science that deals with the research and development as well as the production technology of electrical devices that are at least partly based on electrical energy . This includes the field of converters , electrical machines and components as well as circuits for control , measurement , regulation , communications , device and computer technology through to technical information technology and energy technology .

Electronic switch

Main areas

The classic division of electrical engineering was high- voltage technology, which is reflected today in power engineering and drive technology , and weak- current technology , which formed into communications technology . Electrical measurement technology and automation technology as well as electronics were added as further areas . The boundaries between the individual areas are often fluid. As the applications became more widespread, there were countless other areas of specialization. In our civilization today, almost all processes and facilities are operated electrically or run with substantial involvement of electrical devices and controls.

Theoretical electrical engineering

The basis of the theory and the link to the physics of electrical engineering are the findings from electricity theory . The theory of circuits deals with the methods of analyzing circuits made of passive components. In theoretical electrical engineering , a distinction is made between electrostatics and electrodynamics , the latter as an example, the theory of fields and waves, based on Maxwell's equations .

Electrical Power Engineering

Transmission line and substation

The electrical energy technology (formerly heavy current technology) deals with the generation, transmission and conversion of electrical energy and also high voltage technology . In most cases, electrical energy is obtained by converting mechanical-rotary energy using generators . Classical heavy current technology also includes the area of electrical energy consumers and drive technology. The area of the transmission of electrical energy in the area of low voltage also includes the subject area of electrical installations , as they can be found in various ways in the household.

Classic sub-areas or subjects at technical colleges and universities include electrical power distribution , line theory , high voltage technology , network control technology , power plant technologies , production of electrical energy , electrical machines , energy storage technologies , power electronics , installation technology , protection and isolation technology in energy networks, energy industry (especially electricity industry ), smart Grids , renewable energies .

Electric drive technology

The drive technology , formerly also considered "Power engineering", converts electrical energy by means of electric machines to mechanical energy. Classic electrical machines are synchronous , asynchronous and direct current machines , with many other types, especially in the area of small drives. More recent is the development of linear motors , which convert electrical energy directly into mechanical linear movement without the "detour" via rotation. Drive technology plays a major role in automation technology, as a large number of movements can often be implemented with electric drives. Electronics play a major role in drive technology, on the one hand for controlling and regulating the drives, and on the other hand, kinetic drives are often supplied with electrical energy by power electronics. The area of peak load reduction and energy optimization in the field of electrical engineering has also developed considerably.

Classic sub-areas or subjects at technical schools and universities include electrical machines, rotary field machines , DC machines , reluctance motors , stepper motors , automated drive technology , converters and frequency converters , power electronics, power converters and converter technology .

Communications engineering

By means of the communications technology , and information and communication technology or telecommunications (formerly low power technology) called, signals are generated by electrical conduction or electromagnetic waves as information carrier from an information source (the transmitter ) to one or more recipients (the information sink) transmitted . It is important to transmit the information with such low loss that it can be recognized by the recipient (see also high-frequency technology , amateur radio ). Signal processing , for example by means of filtering, coding or decoding, is an important aspect of communications technology .

Classic partial regions or subjects at colleges and universities include the communication theory , signal theory , digital signal processing and signal conversion , line theory, antenna technology , wireless technology , mobile radio , radio frequency technology and microwave technology , Electromagnetic Compatibility , satellite technology , coding theory .

Electronics, microelectronics and nanoelectronics

Integrated circuit

The electronics deals with the development, production and application of electronic components such as coils or semiconductor devices such as diodes and transistors . The applications are generally practically implemented on printed circuit boards with the printed circuit board assembly.

The Microelectronics is engaged in the development and manufacture of integrated circuits . In some areas the 100- nanometer limit was not reached, so one speaks here formally of nanoelectronics .

The digital technology can be assigned to the extent the electronics is constructed as a classical logic circuit of transistors. On the other hand, digital technology is also the basis of many controls and is therefore important for automation technology. The theory can also be assigned to theoretical electrical engineering.

The development of power semiconductors ( power electronics ) is playing an increasingly important role in drive technology, as frequency converters can provide electrical energy much more flexibly than is possible with transformers, for example .

Classic sub-areas or subjects at technical schools and universities include analog technology , digital technology , PCB design , line theory, chip design , microprocessor technology , microcontrollers , assembler and C programming , embedded systems , electromagnetic compatibility (EMC).

Automation technology

In automation technology , individual work steps of a process are automated or monitored using methods of measurement , control and regulation technology (collectively called MSR technology ). Today the MSR technology is usually supported by digital technology . One of the core areas of automation technology is control technology. Regulations are contained in many technical systems. Examples are the control of industrial robots , autopilots in airplanes and ships, speed controls in engines, stability control ( ESP ) in automobiles, position control of rockets and process controls for chemical plants. Simple examples of everyday life are the temperature controls together with controls in many consumer goods such as irons , refrigerators , washing machines and coffee machines (see also sensor technology ).

Classic partial areas or subjects at colleges and universities include the system theory , engineering cybernetics , control engineering , control engineering , instrumentation , sensors , programmable logic controller , image processing and machine vision , robotics .

New emerging areas of specialization

building technology

The terms technical building equipment (TGA) or supply technology with a focus on electrical engineering are also used. In buildings, electrical installations ensure both the line-based distribution of electrical energy and the possibility of using means of communication ( bells , intercoms , telephones , televisions , satellite reception systems and network components ). In addition to the wired distribution of information, radio transmission ( DECT , WLAN ) is increasingly being used. The building automation utilizes components of the measurement , control and regulation technology in buildings to the use of electrical and thermal energy to optimize for. B. in the field of lighting, air conditioning and ventilation technology. A wide variety of building security systems are also used in the context of building automation .

Medical technology

Electrical engineering and medical technology courses are being offered at more and more universities . Due to the innovative technical developments in the field of medicine , more and more specialized electricians , electrical engineers and engineers are required in hospitals or in medical technology companies and companies .

Areas would, for example Myoelectris , electronics artificial organs, robotic prostheses , Bioprinter , HF surgery , laser surgery , robotic surgery , x-ray machines , ultrasound , magnetic resonance imaging , optical coherence tomography , nuclear medicine , heart-lung machines , dialysis machines , Special Requirements of Clinical Engineering.

Computer, semiconductor and device technology

The electronic device technology , including electronic systems called, emerged from the main area of electronics and focuses on the development and production of electronic assemblies and devices. It thus includes the design and subsequent structural design of electronic systems ( wiring carriers , assemblies , electrical devices ) and makes use of semiconductor technology and computer technology . There is great demand, especially in the areas of computer hardware , household appliances , information technology and entertainment electronics .

History, significant developments and people

antiquity

The phenomenon that certain types of fish (e.g. electric rays or electric eels ) can generate electrical voltages (with the help of the electroplax ) was in ancient Egypt around 2750 BC. Known.

The meteorological phenomenon of thunderstorm lightning has always accompanied mankind. The interpretation that the separation of electrical charges within the atmosphere in thunderstorms causes this phenomenon, however, only occurred in modern times . However, electrostatic phenomena were already known in ancient times.

Thales of Miletus

The first knowledge of the effect of static electricity around 550 BC. Is attributed to the natural philosopher Thales of Miletus . In a dry environment, amber can be electrostatically charged by rubbing it against textile fabric ( cotton , silk ) or wool . What was not known at that time is that amber receives a negative charge by absorbing electrons , whereas the friction material is given a positive charge by releasing electrons. Through the works of Pliny the Elder , the knowledge observed through these experiments was passed down into the late Middle Ages .

17th century

William Gilbert

1600 invented naturalist William Gilbert , the versorium the first version of an electroscope by which he measured the attraction of amber, and then different in the second chapter of the second book of his published work to the magnets between magnetism and static electricity ( "Differentia inter magnetic rica & electrica" ) . Gilbert was the first to use the term electricity , which he derived from the ancient Greek word for amber (ἤλεκτρον; transcribed: ḗlektron; translated: light gold).
1629 discovered Niccolò Cabeo in Ferrara based on further experiments caused by electricity mechanical repulsion and attraction verschiedenster materials and describes first magnetic field lines in "Philo Sophia magnetica".

Otto von Guericke

In 1663 Otto von Guericke invented the first electrifying machine , a sulfur ball with an axis of rotation that generated electricity through hand-induced friction. This machine generates high voltages.
In 1671 Gottfried Wilhelm von Leibniz produced electrical spark discharges with the Otto von Guericke generator and a spark gap . The invention was not published until 1673.

18th century

In 1706, the scientist Francis Hauksbee developed a friction electrifying machine whose ball or cylinder was no longer made of sulfur but of glass . The luminous phenomena of the corona discharge generated by the machine , such as leakage currents and peak discharge, were more visible through the glass .
In 1729 Stephen Gray was the first to divide several substances into electrical conductors and non-conductors .
In 1732, Gray managed to conduct electrical charge over 150 meters through a hemp rope wrapped with silk thread, and in a similar attempt later he sent electricity through metal wires .
1733 Charles du Fay discovered two types of electricity in Paris , positive and negative electricity. Through experiments with static electricity, he discovered that the two types of electricity can neutralize each other.
In 1745, around the middle of the 18th century , Ewald Georg von Kleist and Pieter van Musschenbroek invented the Leiden bottle , the oldest type of capacitor , a component that stores electrical charges.
1746 Johann Heinrich Winkler publishes his view that the electric cloud charge is the cause of a thunderstorm and that it discharges to earth through lightning .
In 1752 Benjamin Franklin invented the lightning rod and published the results of his Experiments and Observations on Electricity from 1751 to 1753 . He demanded and recommended to install lightning rods as lightning protection on every high building.
1756 Franz Ulrich Theodor Aepinus discovers pyroelectricity in tourmaline .
In 1762 Johan Carl Wilcke invented the electrophore , an influenza machine , a method to separate electrical charges or to generate very high electrical voltages .
In 1763, the physicist Andrew Gordon built a horizontally rotating metal star that was electrically charged by a suffering bottle and that rotated when discharged . In some circles he is generally considered to be the inventor of the electric motor .
In 1774 in Berlin , Georges-Louis Le Sage developed and presented the world's first form of electrical telegraphy , using 24 different wires , one for each letter of the alphabet . This telegraph connected two rooms in a building. This was an electrostatic telegraph that moved gold leaves by conducting electrical charges .

In 1775, Alessandro Volta improved the electrophore.

In 1777 Georg Christoph Lichtenberg discovered the " Lichtenberg figures " and based on them the bipolarity of the electrical charge . It was he who introduced the signs “plus +” and “minus -” for electrical charges and poles . With this work he helped to end the dispute between unitarists and dualists.

Piezoelectricity was discovered by RJ Hauy in 1782, but this effect did not gain much attention until 1880 when the brothers Jacques and Pierre Curie presented it to the public as their own discovery.

1785 discovered Charles Augustin de Coulomb , the Coulomb law .

Luigi Galvani

In 1792 Luigi Galvani undertook his legendary frog legs experiment in which an electrochemical galvanic cell served as a voltage source .
In 1795, Francesc Salvà i Campillo reported at the Academy in Barcelona about his first attempts at electric telegraphy and the hypothesis of a possible electric- wireless telegraphy .

19th century

Alessandro Volta

Inspired by Galvani's experiments, Alessandro Volta built the so-called voltaic column around 1800 , the first functioning battery with which a continuous voltage source was available for electrotechnical research for the first time . In 1897 the Si unit Volt was named after him.
On May 2, 1800, the chemists William Nicholson and Anthony Carlisle succeeded for the first time in conducting an electrical current through water with a direct voltage and thus breaking it down into its basic chemical components, hydrogen and oxygen . Both of them are the discoverers of electrolysis .

In 1802, Humphry Davy dealt with electric lighting . He conducted electricity through a platinum thread and made it glow.

In 1804, Francesc Salvà i Campillo built an electrolyte telegraph in Spain with 26 lines , at the ends of which there are glass tubes in which liquids decompose in the event of an electric shock.

In 1809 Davy developed the world's first arc lamp . The first lamp that could give off very bright light over long periods of time.

In 1809 Samuel Thomas von Soemmerring in Germany built an electrolyte telegraph similar to that of Campillo. Today the original is on display in the Deutsches Museum in Munich , a model is in the Museum for Communication in Frankfurt . Sources describe line lengths up to 3.5 km.

In 1816 Sir Francis Ronalds demonstrated in London a telegraph with synchronizing alphanumeric clockworks at both ends. The line length was 13 km. He hypothesized that the transmission of electrical signals has a finite speed . A logical thought, since at that time the speed of light and sound had already been proven.

André-Marie Ampère (1825)

In 1820 Hans Christian Ørsted made attempts to deflect a magnetic needle with an electric current. André-Marie Ampère continued these experiments and demonstrated in 1820 that two conductors carrying current exert a force on one another. Ampère explained the concept of electrical voltage and electrical current and determined the direction of the current. According to him, the Si unit was Ampere named.
In 1820 DF Arago observed that iron, when exposed to electr. Electricity takes on magnetic properties.
1822 Peter Barlow builds the Barlow wheel , a homopolar motor , i.e. a device (without commutator) permanently set in rotary motion with direct current. The first apparatuses, experiments and descriptions of such a machine (a wire permanently rotating in liquid lead) with “Description of an Electro-magnetic Apparatus for the Exhibition of Rotatory Motion” are, however, ascribed to Michael Faraday as early as 1821 , who is generally considered to be the inventor in some circles of the DC motor applies.

In 1825, William Sturgeon was the first to invent and publish the electrical component electromagnet , i.e. a coil with terminals and an iron core to strengthen the field.

Georg Simon Ohm

1826, the physicist, Georg Simon Ohm demonstrate that in a current-carrying metallic conductors which adjusting electric current I to the quotient of applied electrical voltage U and the respective electrical resistance R corresponds. In honor of Ohm, this physical relationship is called Ohm's law . The Si unit ohm was named after him.

In 1828 Ányos István Jedlik built a new version of the direct current motor . However, Jedlik did not report publicly about his machine until decades later and the real time of invention is therefore uncertain.

Discovered in 1831 and explored Michael Faraday the electromagnetic induction , d. H. the generation of an electric current due to a variable magnetic field (reversal of Oersted's discovery).

In 1832 Paul Schilling von Cannstatt built the world's first electromagnetic telegraph with rotating magnetic needles.

In 1832 Antoine-Hippolyte Pixii invented the alternator , a machine that, when turned on a lever , gives an alternating voltage to the terminals.

In 1833 Emil Lenz published the Lenz rule , which today u. a. has a high priority in electricity science.

In 1833, Carl Friedrich Gauß and Wilhelm Eduard Weber invented the relay together to build an improved electromechanical telegraph. A telegraph that no longer consisted of a remotely triggered electrochemical decomposition of a liquid, but a remotely triggered electromechanical movement (opening / closing) of a relay.

In 1833 Michael Farraday discovered that certain materials behave differently electrically than typical metallic conductors. z. B. observed that the resistance of silver sulfide decreases with temperature, which is the opposite of the dependence observed for metals. In many circles he is considered to be the discoverer of semiconductors and the founder of semiconductor technology .

In May 1834 Moritz Jacobi developed the first rotating electric motor with direct current, which actually gave a remarkable and useful mechanical performance. He was thus able to build the world's first electric boat (Das Jacobi-Boot ), which he demonstrated in 1838 with a trip on the Neva in Saint Petersburg (with 0.3 kW 7.5 km 2.5 km / h ). In 1839 he was able to increase the mechanical power of his engine to 1 kW and then reached speeds of up to 4 km / h with the boat.

In 1834 Charles Wheatstone experimentally determined the current speed of 400,000 km / s in England, which was still relatively imprecise, and thus verified the hypothesis that the current speed, like the speed of light and sound, is finite.

On July 25, 1835, James Bowman presented an electric light bulb to Lindsay in Dundee . I.e. the world's first electric light source with a glass bulb.

In 1835 Emil Lenz described the temperature dependence of the electrical resistance in metals in a formula .

In 1837 Thomas Davenport received the world's first patent for a direct current electric motor . He had submitted the patent as early as 1835 and in the same year built a mini-model of an electrically powered rail vehicle on a rail circle four feet in diameter using the electric motor he had developed . This was the world's first electrically powered rail vehicle .

Samuel Morse (1840)

In 1840, Samuel FB Morse and his colleagues built a significantly improved electrical telegraph using his invented Morse code .
1845 formulated Gustav Kirchhoff , the Kirchhoff's circuit laws , basic laws of electrical engineering.
In 1847 Louis Clément François Breguet published the idea of a fuse to protect equipment and cables from lightning strikes. However, it was only patented (US438305A Fuse Block) on October 14, 1890 by Thomas Edison, who also recognized its importance as a protection element for future power grids against lightning or excessive currents.
In 1854 Wilhelm Josef Sinsteden invented the lead accumulator .
In 1857 Heinrich Geißler invented the fluorescent lamp .
The first transatlantic telegraph connection was established in 1858. An over 4500 km long submarine cable was laid between Ireland and Newfoundland .
In 1859 George B. Simpson registered the patent (US25532A electrical heating apparatus) and thus invented the electric stove . He integrated a wire into the plate of a coal stove and the voltage source was still a battery back then.
In 1860 Antonio Meucci and Philipp Reis invent the electric telephone . Philipp Reis invented the telephone and thus electrical voice transmission in 1860 at the Garnier Institute in Friedrichsdorf . However, not much attention was paid to his invention, so that it was not until 1876 that Alexander Graham Bell designed and successfully marketed the first economically usable telephone in the USA .
In 1861 Ányos István Jedlik invented the direct current generator , associated with the term dynamo. If so, it would be 5 years before Werner von Siemens, who is considered in many circles as the inventor of the dynamo. There are supposed to be records that even state that Søren Hjorth received the first patent for a self-excited dynamo machine as early as 1854 .

James Clerk Maxwell

Michael Faraday made a great contribution in the field of electric and magnetic fields, from whom the term " field line " originates . Faraday's findings formed the basis for James Clerk Maxwell's work. He completed the theory of electromagnetism on electrodynamics and its mathematical formulation. The quintessence of his work, the Maxwell equations , filed in 1864 and published in 1865 , are one of the most fundamental theories in electrical engineering.

Werner from Siemens

One of the pioneers of " heavy current technology " was Werner Siemens (from Siemens from 1888), who in 1866 developed the first electric generator for industrial purposes using the dynamo-electric principle . For the first time, electrical energy was available in a usable amount.

In 1871, Zénobe Gramme showed a new version of the direct current machine , the Gramme machine or Grammescher Ring. In 1873 Hippolyte Fontaine found out that the Gramme machine, a direct current motor, could also be used as a direct current generator without modification. Thus he discovered the energy reversibility of electrical machines.

In 1873 Frederick Guthrie discovered that a positively charged electroscope would discharge if you brought a grounded, glowing piece of metal near it. With a negatively charged electroscope, nothing happens, from which it concluded that the electrical current in this piece of metal could only flow in one direction. In 1874, Karl Ferdinand Braun discovered directional electrical conduction in certain crystals at the university . Thus both discovered the rectifying effect of semiconductors and invented the semiconductor diode , a component that is one of the most important semiconductor components in electronics.

In 1879, Siemens coined the word electrical engineering when he suggested to Heinrich von Stephan that an electrical engineering association should be founded. As its first president, he campaigned for the establishment of chairs in electrical engineering at technical universities throughout Germany.

Thomas Edison

Nikola Tesla (1890)

In 1879 Thomas Alva Edison invented the carbon filament incandescent lamp, a significantly improved version of previous incandescent lamps, and thus brought electric light to people. As a result, electricity found its way into ever larger areas of life. At the same time, Nikola Tesla and Michail von Dolivo-Dobrowolsky worked , pioneers of alternating current and about 8-10 years later with their pioneering inventions laid the foundations for today's energy supply systems.
1880 The world's first electric passenger elevator .
1881 was held in Paris the first International Electricity Exhibition and the first international congress electricity instead.
In September 1882, Edison began to build the first power plants in Manhattan to supply the electricity for his DC voltage networks in the city. In order to electrify the cities, he had to build a power plant every 800 meters , since direct current is very uneconomical to transport and distribute over long distances. It was already clear that electrification in the countryside would be very uneconomical.
In 1882, Lucien Gaulard and John Dixon Gibbs invent the transformer , which they initially called the "secondary generator". With this new invention in 1883 they were able to transmit alternating current with 2000 volts over a test route of 40 km with low losses and small copper conductor cross-sections, and in 1884 they were able to make a test route between Turin and Lanzo of 80 km possible. This showed that alternating current can be transported and distributed more economically than the direct current favored by Edison for the power grid . There were already lamps for alternating current. However, there were still no usable AC motors.
On February 1, 1883, Edison introduced the world's first electricity meter for its power grids . This electricity meter, known as the Edison meter, could only record direct currents.

In 1883 Erasmus Kittler founded the world's first degree in electrical engineering at the TH Darmstadt (today TU Darmstadt). The course lasted four years and ended with an examination to become an “ electrical engineer ”. In 1885 and 1886 the University College London (GB) and the University of Missouri (USA) followed, which set up additional independent chairs for electrical engineering. The engineers trained in this way were required to enable large-scale electrification.
In 1884 Paul Nipkow patented the Nipkow disk , which he called the " electric telescope ". This created the basis for electromechanical television .

George Westinghouse

On March 20, 1886, William Stanley demonstrated in Great Barrington Massachusetts the first US AC voltage transmission and distribution using generators, transformers and a high-voltage line over a short distance of several hundred meters. In the summer of 1886, George Westinghouse in Pittsburgh tested the same system with a test distance of 3 miles. From then on, Edison's propaganda began against the alternating current system, which would go down in history in the USA as the so-called current war ( AC alternating current versus DC direct current ).

Heinrich Hertz

On November 13, 1886, Heinrich Hertz succeeded in proving the Maxwell equations experimentally. The Berlin Academy of Sciences he taught on 13 December 1888 in its research report "blooming electrical power" on the electromagnetic waves . By proving the existence of electromagnetic waves, he became the founder of wireless communications technology.
On October 12, 1887 announces Nikola Tesla a two-phase synchronous - AC motor for a patent (US381968A Electro-magnetic motor). According to him, he invented the principle as early as 1882. It was the first usable motor for alternating current. Through this invention, I became acquainted with Westinghouse, who also recognized the great advantages of alternating current and was ready to buy all of Tesla's patents.
On March 11, 1888, Galileo Ferraris published his research results on two-phase and multi-phase asynchronous AC motors (induction motors) at the university. Rotary field machines like these have the advantage that they can do without slip rings and commutators . However, he wrongly concluded in his work based on a misconception that these motors are very energy inefficient, so that he stopped research in this area.
On May 1, 1888, Tesla applied for a patent for the induction motor (two-phase asynchronous motor) (US382279A Electro Magnetic Motor). Thus Ferraris and Tesla are considered in many circles to be the inventors of the induction motor (multi-phase asynchronous machine). In 1893, at the World's Columbian Exposition, the Tesla Columbus Egg (Tesla's Egg of Columbus) was presented, which should illustrate the principle of the induction motor. According to Tesla, he had shown it to a New York investor as early as 1887 in order to raise funds for his AC technology.

Michail Dolivo-Dobrowolski (1908)

Inspired by the research results of Ferraris, Michail von Dolivo-Dobrowolsky invented the three-phase asynchronous machine (three-phase asynchronous motor) and three-phase synchronous machine in 1888 , and was the first to experiment with star-delta starting circuits and three-phase slip ring motors , and immediately afterwards developed generators with three-phase alternating current , the alternating current system that has prevailed in the electrical energy distribution and transport networks to this day. In the USA, however , Geoge Westinghouse stuck to Nikola Tesla's two-phase AC four - wire system for a few years .

In August 1889, Michail von Dolivo-Dobrowolsky received the patent for a three-legged three - phase transformer . This marked the beginning of the triumphant advance of three-phase alternating current.

Alexandre-Ferdinand Godefroy invented the forerunner of a hair dryer in 1890 and used it in his hair salon in Paris .

1890 J. Joubert introduces the term " impedance " into electrical engineering (alternating current technology) in France .

In 1891 the engineer Oskar von Miller and Michail von Dolivo-Dobrowolsky manage and build the three-phase transmission Lauffen – Frankfurt , the first transmission of electrical energy with high voltage three-phase current (175 km with 25 kV).

1891 results Silvanus Phillips Thomson the term power factor "cos" into the electrical (AC technology).

January 1893 Foundation of the Association of German Electrical Engineers (VDE), today the Association of Electrical, Electronics and Information Technology (VDE).

In 1893 the electrical engineer Charles Proteus Steinmetz laid the foundations of the complex alternating current calculation, this calculation method is an operator calculation .

In 1894, CP Steinmetz in the USA introduced the term reactance "reactance" and G. Kapp in England the term " power factor " in electrical engineering (alternating current technology).

At the end of 1896, the first US electrical power transmission using high-voltage transmission lines was inaugurated. Built by Tesla and Westinghouse, it leads from Niagara Falls to the city of Buffalo, New York State, over a distance of 22 miles (35 km at 11 kV). This line is a three-phase three-phase system, but with three single-phase transformers, as the three-legged three-phase transformer is patented by Dobrowolsky. The aim was to get the hydropower of Niagara Falls into the big cities . This success ended the electricity war in favor of alternating current.

Guglielmo Marconi (1907)

Alexander Popov

In 1896, Alexander Popov carried out wireless signal transmission over a distance of 250 m. In contrast to Marconi, Popow failed to patent his invention. Guglielmo Marconi therefore earned the credit for the first practical use of spark telegraphy . After he had applied for a patent for his spark telegraph in Great Britain in June 1896, Marconi transmitted a Morse code over a distance of 5.3 kilometers in May 1897. On December 12, 1901, Marconi celebrated his great triumph: For the first time in history, a person sent a radio message across the Atlantic . He sends the letter "S" via Morse code. In 1909, Marconi and Ferdinand Braun received the Nobel Prize for this achievement. However, Tesla is said to have demonstrated such radio systems as early as 1893 and filed several patents in the years that followed. However, Tesla dedicated his time to realizing wireless transmission of energy instead of transmitting messages. In 1943, the American Supreme Court recognized Nikola Tesla as the sole inventor of the radio because Marconi infringed 17 of Tesla's patents on his radio systems.

The electron was first detected as an elementary particle by Joseph John Thomson in 1897 (he first called it corpuscule ). He later gave the elementary charge the name electron .

In 1897 Karl Ferdinand Braun developed the first cathode ray tube . Improved variants were initially used in oscilloscopes and decades later as picture tubes in fully electronic television sets and computer monitors .

20th century

In 1903 the Schuckert company (DRP Patent No. 160.069) invented and patented the residual current circuit breaker (also RCD) under the name of summation current circuit for earth fault detection , a technical device that is used today in all modern fuse boxes and in power networks.

Christian Hülsmeyer is considered to be the inventor of the radar . In 1904 he received a patent (Reich patent no. 1655461) for a device which he called "Telemobiloskop".

In 1905, electrical engineer John Ambrose Fleming invented the first radio tube, the diode . In 1906 Robert von Lieben and Lee De Forest independently developed the amplifier tube, known as a triode , which gave radio technology a major boost.

Ferdinand Braun (1909)

On June 8, 1906, the electrical engineer Dr. Max Dieckmann and his colleague Gustav Glage with a " two-slide apparatus" - against the will of Braun, who considered such applications to be unscientific gimmicks. This proved the suitability of the cathode ray tube as an image writer (for the transmission of characters). In the same year he used a Braun tube to reproduce 20-line shadowy shadow images in the format 3 × 3 cm. This was probably the world's first all-electric television monitor .
June 26, 1906 Founding of the I nternational E lectrotechnical C ommission (IEC) , an international standards organization for standards in the field of electrical engineering and electronics .
In December 1906, the electrician Reginald Fessenden achieved the world's first wireless transmission of simple tones with a machine transmitter , as did Valdemar Poulsen with his arc transmitter in 1904 (published in 1906) .

1907 or 1908, the first electric-powered commercial came washing machine on the market, from the "1900" Washer Company of Binghamton ( New York ) and the Hurley Machine Co. of Chicago .

The electrical charge was determined in 1907 by Robert Millikan . The electron charge, also known as the elementary charge as the smallest free quantum of charge, is 1.602 · 10 ⁻¹⁹ C ( Coulomb ). Milikan received the Nobel Prize for this discovery.

In 1907, Henry Joseph Round discovered the round effect , also known as electroluminescence , which he published in the same year in the journal Electrical World, the effect that inorganic substances emit light when an electrical direct voltage is applied, a discovery that Oleg Vladimirovich Lossew developed in 1927 a practical drive application, the light-emitting diode (LED).

In 1911, JG Königsberger and J. Weiss introduced the term “ semiconductor ” and “ semiconductor technology ” in electrophysics and electrical engineering.

1912 H. Ford , automobile manufacturer , is the first in the world to equip its automobiles with electric starters .

In 1913 the engineer Alexander Meißner patented the Meißner circuit . Until 1913, transmitters could only be switched on and off, which at best can be described as very rudimentary modulation. Modulation with a wide variety of signals, the subtle nuances of which also have to be transmitted (e.g. speech tones and music), requires an oscillator circuit that initially generates a constant signal - this was only possible after the invention of the Meissner circuit. That was the beginning of broadcasting .

In 1914, the world's first electrically operated traffic light was installed in Cleveland , Ohio .

1924 invented Hugo Stotz the circuit breaker (also breaker) that comes in this day and age with all modern safety and junction boxes are used.

In 1925, the electrical engineer John Logie Baird built the first (mechanical) television based on the Nipkow disk using the simplest means .

Takayanagi Kenjiro (1953)

In 1925, the electrical engineer Dr. Kenjiro Takayanagi with Baird's kind of image decomposition, but used to play back the images a cathode ray tube . In 1926 Takayanagidie succeeded in the world's first fully electronic transmission of images with cathode ray tubes on the transmitter and receiver side, i.e. H. the world's first all-electric television, before Philo Farnsworth who demonstrated a similar system a few months later. Takayanagi reproduced the Katakana character イ recorded earlier on a Braun tube.
In 1926 Julius E. Lilienfeld files a valid patent (US1745175A Method and apparatus for controlling electric currents) for his invented field effect transistor , but these could not be manufactured until 1960, when a material system was available with silicon / silicon dioxide . The various variants of field effect transistors are among the most important semiconductor components in modern electronics, microelectronics, nanoelectronics and power electronics. The field effect transistors today allow u. a. efficient converters , converters and switched-mode power supplies , and high integration density of modern chips.
In 1927, the development of FM radio began in the field of radio, which was able to establish itself in Europe for ultra-short wave and VHF radio . By 1933, the electrical engineer Edwin Howard Armstrong filed four patents dealing with the technology of frequency modulation . The world's first commercial FM radio stations appeared in the USA in the late 1940s.
In 1928 the first color television followed by Baird and in the same year he succeeded in transmitting the first transatlantic television transmission (television technology with mechanical image splitting ) from London to New York.

Konrad Zuse (1992)

In 1941 the engineer Konrad Zuse completed the world's first functional computer , the Z3 ; it was the first electromechanical computer. In 1946 the ENIAC ( Electronic Numerical Integrator and Computer ) by John Presper Eckert and John Mauchly followed . The first phase of the computer age began. The computing power available in this way enabled engineers and society to develop completely new technologies and achieve achievements. An early example is the moon landing as part of the Apollo program of NASA .
In 1945 the engineer Percy Spencer discovered by chance that you could heat food with microwaves , and in 1946 he built the world's first microwave oven .

Replica of the first transistor from (1947)

The invention of the bipolar transistor in 1947 at Bell Laboratories (USA) by William B. Shockley , electrical engineers John Bardeen and Walter Brattain and the entire semiconductor technology opened up a wide range of applications for electrical engineering, as many devices could now be built very compactly. Another important step in this direction was the development of micro-integration: The integrated circuit (IC) invented by Jack Kilby in 1958 made today's processor chips and thus the development of modern computers possible in the first place. In 2000 he received the Nobel Prize for it .

1947 Electrical defibrillation on humans by Sweet and Claude Beck .

1951 World's first mass production of transistors at Allentown Works .

In 1953, the members agreed the National Television System Committee (NTSC) unanimously for the w orld's first international standardization or standardization for the transmission, reception and processing electrically analog color television signals . However, the standard was not able to assert itself in many industrialized countries, so that, depending on the world region, various standards have asserted themselves, such as B. PAL and SECAM .

1954 originated in Sweden , Gotland , the world's first commercial HVDC connection.

In 1956, the first transatlantic telephone network was created with TAT-1 (German transatlantic telephone cable no. 1) .

In 1957 General Electric (GE) presented the thyristor ( silicon controlled rectifier) and, as a second variant, the triac , important components of power electronics.

In 1958, George Devol and electrical engineer Joseph Engelberger invented and built the world's first industrial robot in the USA . Such a robot was first used in industrial production at General Motors in 1960. Industrial robots are used today in a wide variety of industries, such as B. the automotive industry, an important component of automation technology .

In 1958, the analogue, hand-switched A network was introduced by the German Federal Post Office under the name of Public Mobile Land Radio Service (ÖbL). The A-Netz was the first mobile radio system for telephony in the Federal Republic of Germany and reached its technical limits as early as 1971. The successor was the B network in 1972 .

Karl Kordesch (2003)

In 1960 Karl Kordesch patented the alkali-manganese cell , which is one of the most important electrochemical energy storage devices .
In May 1960, the physicist Theodore Maiman , son of an electrical engineer, and his assistant Charles Asawa developed the world's first functional laser , the ruby laser .
In 1961, the electrical engineer invents James L. Buie at TRW , the TTL technology , which in the 70s, 80s, the dominant digital technology was but even today is still a standard.
On July 10, 1962, the United States launched Telstar 1, the world's first civil communications satellite, into space .
In 1962, Gerhard Sessler and James E. West invented the electret microphone , which was then still the most widely produced microphone in the world. It is Z. B. Part of cell phones and cassette recorders .
In 1963 the engineer Dr. David Paul Gregg invented the first digital camera , a camera that stores images electronically. He is also considered the inventor of the optical data carrier .
1963 Foundation of the Institute of Electrical and Electronics Engineers (IEEE).
1963 developed the electrical engineer Frank Wanlass the semiconductor manufacturer Fairchild Semiconductor the CMOS technology . The technology led to significantly lower power consumption compared to bipolar transistors which z. B. can be used in TTL technology. CMOS technology is the most widely used digital technology in modern electronics and microelectronics today.
1965 formulated Gordon Moore , the Moore's Law , a rule of thumb that an empirical returns observation. Some claim that this predicts that technical developments in general could be exponential.
In 1965 Shin'ichirō Tomonaga , Julian Schwinger and Richard Feynman received the Nobel Prize in Physics “for their fundamental achievement in quantum electrodynamics , with profound consequences for elementary particle physics”. Quantum electrodynamics (QED) is in the context of quantum physics , the quantum field theoretical description of electromagnetism .
In 1967 the American electrical engineer George Heilmeier developed the world's first liquid crystal display, "Liquid Crystal Display" (LCD) .

Marcian Ted Hoff (2009)

In 1968, the American electrical engineer Marcian Edward Hoff , known as Ted Hoff , invented the microprocessor at Intel , heralding the era of the personal computer (PC). Hoff's invention was based on an order from a Japanese company for a desktop computer that he wanted to realize as cheaply as possible. In 1971, Federico Faggin developed the first commercial realization of a microprocessor almost single-handedly, the Intel 4004 , a 4-bit processor. But it wasn't until the Intel 8080 , an 8-bit processor from 1973, that the first PC, the Altair 8800, could be built .

In 1970, the American company Corning Inc. produced and developed the first fiber-optic cable that was able to transmit signals over long distances without major losses. This was a revolutionary step and enabled the economical construction of fiber optic networks .

With his patent filed in 1973 (US3906166A Radio telephone system), the American electrical engineer Martin Cooper is considered to be the inventor of the portable cell phone ("pocket phone "), i. H. the world's first compact mobile phone designed to be carried around by humans. At that time there were already forerunners of the cell phone which z. B. were permanently installed in trains and in cars and used the A network .

1973 developed P. Ch. Lauterbur in the US imaging magnetic nuclear magnetic resonance , the magnetic resonance imaging MRI. In 2009 around 5.89 million people in Germany received at least one magnetic resonance tomography.

In 1974 the first microcontroller appeared on the market, the Texas Instruments TMS1000 .

In 1976 the chemist H. Shirakawa developed conductive polymers and thus the basis for organic light-emitting diodes . This technique finds u. a. Use on OLED screens. The polymer-based semiconductors are assigned to the new area of organic electronics .

In 1978, the Philips company invented the compact disc (CD) for storing digital information. In 1982, a cooperation between Philips and Sony resulted in the audio CD. The CD-ROM followed in 1985.

In 1979 Sheldon Glashow , Steven Weinberg and Abdus Salam received the Nobel Prize in Physics “for their contributions to the theory of the unified weak and electromagnetic interaction between elementary particles, including u. a. the prediction of weak neutral currents ”( Electroweak Interaction ).

The first attempts to digitize telephone networks began in the 1970s, but it wasn't until 1980 that ISDN appeared as the international standard for the digital telecommunications network .

In 1982 Stanford R. Ovshinsky and Masahiko Oshitani developed the nickel-metal hydride accumulator between 1962 and 1982 as a market-ready cell.

Martin Cooper (2007)

1983 Together with chief designer Rudy Krolopp , Martin Cooper and the Motorola company brought the DynaTAC 8000X to the market, the world's first mass-produced mobile phone ("pocket phone") . Just one year later (1984), 300,000 people owned the forefather of the modern cell phone.

In 1988, TAT-8 was the first transatlantic fiber optic network. TAT-8 enabled 280 Mbit / s (40,000 telephone connections simultaneously).

1990 GSM ("2G"), the world's first mobile radio standard for fully digital mobile radio networks, is introduced.
In 1990 the ASTC set the world's first standards for digital television (in the USA) .
In 1991 the first lithium-ion battery appeared on the market.
In 1994, the first DVB standards for digital television were set in Europe .
In 1994, the world's first digital television was commercially available via satellite under the brand name DirecTV in the United States .

Honda P2 (2008)

In 1996, the Honda company presented the world's first functional humanoid robot, the P2. The Japanese Waseda University developed the first prototypical humanoid robot , which was not yet fully functional, as early as 1976 . The current Android, Honda's 1.20 m tall Asimo, resulted from the P2 . In addition to many electronic and electrotechnical components, humanoid robots also essentially consist of mechanical components, the interaction of which is known as mechatronics .

In 1999 in the United States with the National Electrical Code arc fault protection devices (fire protection switch) required or recommended for specific spaces and buildings, with the Canadian Electrical Code pulled Canada in 2002, with the DIN VDE 0100-420 Germany in 2016 after. This modern electronic circuit breaker is built into fuse and distribution boxes . According to a study by the Institute for Loss Prevention and Loss Research of Public Insurers , electricity, at 32%, was the most common cause of fire in Germany with significant damage to buildings between 2002 and 2019. The first patents have been filed, for example by Siemens Energy & Automation , EU patent EP0653073B1 in 1992, or Square D , EU patent EP0820651B1 in 1997.

21st century

In 2000, Digital Audio Broadcasting (DAB) set the first standards for digital radio in Europe .

2,000 were in Germany licenses for the mobile radio standard of the third generation ( "3G") Universal Mobile Telecommunications System issued (UMTS) that higher data rates for mobile cellular networks and mobile Internet allows up to 384 kbit / s , starting in 2011 with HSPA + incl. Backward compatibility up to 42 Mbit / s .

In 2002, the 100 nanometer structure widths for commercially manufactured integrated circuits (90 nm DRAMs from Toshiba ) in mass production were undercut. The semiconductor industry below this limit is very often assigned to the now emerging area of nanoelectronics .

In 2009, the world's first commercial LTE networks went into operation. LTE is the fourth generation (“4G”) cellular standard and enables up to 300 Mbit / s and lower latencies , from 2014 with LTE-A (“4G +”) including downward compatibility up to 1 Gbit / s .

In 2018, the world's first commercial high-voltage direct current transmission with over 1 megavolt went into operation in China . A 1100 kV HVDC link between Changji and Guquan, with a length of 3,284 km and a transmission capacity of up to 12 gigawatts . The distance corresponds to about 8.2% of the circumference of the earth and the power about that of 13 nuclear reactors .

In 2019, the world's first nationwide and commercial 5G networks and services went into operation in South Korea . This fifth generation cellular standard enables up to 20 Gbit / s and latencies of 0.5 to 4 ms .

Education, training and study

Apprenticeships

Advanced training

Further training to become an electrician takes place at a master ’s school and lasts 1 year full-time or 2 years part-time. Further training to become an electrical engineer can be completed at a technical school in 4 full-time semesters or 8 semesters part-time.

Subject

The electrical engineering course was first established by Erasmus Kittler in January 1883 at the Darmstadt University of Technology . The curriculum provided for a four-year course with a final examination (for a degree in electrical engineering).

Electrical engineering is now offered as a degree program at many universities , technical colleges and vocational academies . At universities, academic work is emphasized during the course of studies, while at universities of applied sciences and vocational academies the focus is on the application of physical knowledge.

Basic studies

The first semesters of an electrical engineering degree are characterized by the courses Fundamentals of Electrical Engineering , Physics and Higher Mathematics . The basic physical principles of electrical engineering are taught in the basics of electrical engineering. This electricity theory covers the following topics:

Direct current technology : electrical potential , electrical voltage , electrical current , ohmic resistance , Kirchhoff's theorems , composite circuits, electrical work and power, power adjustment;

AC technology : complex AC calculation ; Reactance , active and reactive power , passive and active two-pole , resonant circuit , locus curve ;

Polyphase alternating current , symmetrical and asymmetrical three-phase system , switching processes, periodic oscillations with non-sinusoidal curve shape, Fourier series ;

Electrostatics : static electric field , influence , Coulomb's law , electric charge , electric capacity ;

Electrodynamics : time-varying magnetic and electric fields, electromagnetic induction , Maxwell's equations .

Further basic subjects are electrical measurement technology , digital technology , electronics, and network and system theory . Due to the interdisciplinary nature and the close integration with computer science , programming is also part of an electrical engineering degree. If programming and information technology occupy a large part of the timetable, the degree is very often called electrical engineering and information technology .

Specialization or specialization

Priorities can be set in the higher semesters of the bachelor's and master's degree. In some courses of study, specialization subjects can be freely selected from a broad catalog or the specialization area can be selected or has already been determined. Classical specializations or specializations include, for example, electrical power engineering , communications technology , electronics , automation technology and measurement, control and regulation technology (MSR) , drive technology . New specializations are for example electronic systems and microelectronics, renewable energies , technical building equipment (TGA), medical technology .

Courses that specialize in a combination of two areas of specialization that are very closely related in practice are also offered, such as energy and automation technology, energy and drive technology, communications technology and electronic systems, medical technology and electronic systems, energy technology and renewable energies.

Interdisciplinary compulsory and elective subjects

Since the job of electrical engineer very often also requires interdisciplinary knowledge , depending on the university, compulsory and elective subjects such as materials science , business administration , English , technical mechanics , technical drawing , patent law , occupational health and safety , labor law , communication must be passed.

Academic title

The academic degree of Diplom-Ingenieur (Dipl.-Ing. Or Dipl.-Ing. (FH)), which has been awarded by universities for decades , was based on the Bologna Process through a two-stage system of professional qualifications (typically in the form of Bachelor and Master ) largely replaced. The Bachelor ( Bachelor of Engineering or Bachelor of Science ) is a first professional academic degree which , depending on the examination regulations of the respective department, can be acquired after a study period of 6 or 7 semesters. This first academic degree enables the legally protected title of “ engineer ” or “electrical engineer” to be used. After a further study period of 4 or 3 semesters, the Master can be obtained as a second academic degree ( Master of Engineering or Master of Science ).

The doctoral engineer (Dr.-Ing.) Is the highest academic degree that can be achieved following a completed master’s degree as part of an assistant doctorate or in a graduate school . The engineering honorary doctorate (Dr.-Ing. E. h.) May be awarded by universities for special academic or scientific merits of academic or non-academic, for example, 1911 Mikhail Dolivo-Dobrovolsky from the Technical University of Darmstadt.

Teaching position

At some universities, the Bachelor's degree in Electrical Engineering and Information Technology can be studied in seven semesters, followed by a three-semester Master's degree in Vocational Education . With this master’s degree and after a further 1.5 years of legal traineeship, there is the possibility of finding a job as a trade teacher ( higher service ) at a vocational school .

Associations

International

The largest professional association for electrical engineering worldwide is the Institute of Electrical and Electronics Engineers (IEEE). It has over 420,000 members and publishes magazines in all relevant fields in English. The IEEE Global History Network (IEEE GHN) has existed since 2008 , whereby important milestones (assessed by a specialist committee) and personal memories of engineers ( IEEE First-Hand History ) can be recorded in various categories . Such reminder reports from Swiss electrical engineers can be viewed as examples. Since the beginning of 2015, the IEEE GHN has joined an expanded organization, Engineering and Technology History Wiki , which encompasses other engineering departments.

National

The VDE Association of Electrical, Electronic and Information Technologies e. V. is a technical-scientific association in Germany. With around 35,000 members, the VDE is committed to a better climate for innovation, safety standards, modern engineering training and a high level of technology acceptance among the population.

The Central Association of German Electrical and Information Technology Trades (ZVEH) represents the interests of companies from the three trades of electrical engineering, information technology and electrical engineering. ZVEH members in 2014 were 55,579 companies with 473,304 employees, including around 38,800 trainees. As a federal guild association, the ZVEH has twelve professional and regional guild associations with a total of around 330 guilds.

The Zentralverband Elektrotechnik- und Elektronikindustrie e. V. (ZVEI) advocates the interests of the electrical industry in Germany and on an international level. ZVEI members are more than 1,600 companies that employed around 844,000 people in Germany in 2014. There are currently 22 professional associations as ZVEI subdivisions.

literature

Winfield Hill, Paul Horowitz: The high school of electronics, part 2, digital technology . Elektor-Verlag 1996, ISBN 3-89576-025-0 .
Eugen Philippow , Karl Walter Bonfig (edit.): Fundamentals of electrical engineering. Verlag Technik, Berlin, 10th edition 2000, ISBN 3-341-01241-9 .
Winfield Hill, Paul Horowitz: The high school of electronics, Part 1, analog technology . Elektor-Verlag 2002, ISBN 3-89576-024-2 .
Manfred Albach : Fundamentals of electrical engineering 1. Theories of experience, components, direct current circuits. Pearson Studium, Munich 2004, ISBN 3-8273-7106-6 .
Manfred Albach: Fundamentals of electrical engineering 2. Periodic and non-periodic signal forms. Pearson Studium, Munich 2005, ISBN 3-8273-7108-2 .
Gert Hagmann : Fundamentals of electrical engineering . 11th edition, Wiebelsheim 2005, ISBN 3-89104-687-1 .
Helmut Lindner , Harry Brauer, Constanz Lehmann: Paperback of electrical engineering and electronics. Specialist book publisher at Carl Hanser Verlag, Leipzig; Munich, 9th edition 2008, ISBN 978-3-446-41458-7 .
Siegfried Altmann , Detlef Schlayer: Text and exercise book electrical engineering. Fachbuchverlag, Leipzig; Cologne 1995, 4th edition: Fachbuchverlag im Carl Hanser Verlag, Leipzig; Munich 2008, ISBN 978-3-446-41426-6 .
Wolfgang König : Technical Sciences. The emergence of electrical engineering from industry and science between 1880 and 1914. Chur: G + B Verlag Faculties, 1995. ISBN 3-7186-5755-4 (softcover).
Henning Boëtius , the history of electricity told by Henning Boëtius. 1st edition, Beltz & Gelberg, ISBN 978-3-407-75326-7 .
Siegfried Buchhaupt: Technology and Science: The Example of Electrical Engineering . In: Technikgeschichte, Vol. 65 (1998), H. 3, pp. 179-206.

Web links

Wiktionary: Electrical engineering - explanations of meanings, word origins, synonyms, translations

Wikibooks: Electrical engineering formulas - learning and teaching materials

Wikibooks: Electricity formula collection - learning and teaching materials

Wikibooks: Shelf: Electrical engineering - learning and teaching materials

Wikisource: Electrical Engineering (1914) - Sources and full texts

Videos

Individual evidence

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↑ Electrical conductivity. In: uni-ulm.de. Ulm University, accessed on March 29, 2019 .
↑ u. a. Round Andreas: Chapter lightning. In: Chronicle of electrical engineering. VDE-Verlag, April 3, 2017, accessed on May 10, 2020 .
↑ Konrad Reichert and u. a .: electric motor and electric drives. In: Chronicle of electrical engineering. VDE, 2016, accessed on May 10, 2020 .
↑ Electrostatic application: telegraphy. In: uni-ulm.de. Ulm University, accessed on March 29, 2019 .
^ Georg Christoph Lichtenberg (1742 to 1799). In: uni-goettingen.de. Georg-August-Universität Göttingen, accessed on March 29, 2019 .
↑ He knew how to combine plus and minus. In: rhetorik-netz.de/bio_lich/. Retrieved March 29, 2019 .
↑ May 2, 1800. In: funkzentrum.de. Retrieved March 25, 2019 .
^ Henning Boëtius: History of electricity . 1st edition. Beltz & Gelberg, Germany 2006, ISBN 978-3-407-75326-7 .
^ Early Wired Telegraphy. Harvard, September 18, 1999, accessed March 25, 2019 .
^ Samuel Thomas von Sömmerring: Biography. The Engineering and Technology History Wiki (ETHW), February 26, 2016, accessed on March 25, 2019 .
↑ Francis Ronalds 1816. madeupinbritain.uk, July 5, 2017, accessed March 25, 2019 (English).
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↑ Martin Doppelbauer: The Invention of the Electric Motor 1800–1854: Davenport - The Inventor of the Electric Motor? In: www.eti.kit.edu. KIT, September 24, 2014, accessed on March 19, 2019 .

^ The Editors of Encyclopaedia Britannica: Thomas Davenport - AMERICAN INVENTOR. In: Encyclopaedia Britannica. Encyclopaedia Britannica, accessed March 19, 2019 .

↑ James Clerk Maxwell: A Dynamical Theory of the Electromagnetic Field . Submitted in 1864 and then published in: Philosophical Transactions of the Royal Society of London (155), 1865, pp. 459-512.

↑ David Laws: WHO INVENTED THE DIODE? In: https://computerhistory.org/ . November 6, 2011, accessed June 7, 2020 .

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^ Albrecht Fölsing : Heinrich Hertz. Hoffmann and Campe, Hamburg 1997, ISBN 3-455-11212-9 , p. 275.

↑ ^a ^b ^c KIT Karlsruhe Institute of Technology: The Invention of the Electric Motor 1856–1893 A Brief History of Electric Motor Technology - Part 2. In: https://www.eti.kit.edu/ . Karlsruhe Institute of Technology, January 5, 2018, accessed on March 13, 2019 .

↑ Joachim Beckh: limited preview in the Google book search

↑ Ndja Podbregar: The first radio - Tesla, Marconi and a Morse "S". scinexx.de, October 27, 2017, accessed April 15, 2019 .

↑ Leland Anderson: The Supreme Court of America recognized all of Nikola Tesla's patents as the sole inventor of the radio. In: teslasociety.ch. January 7, 2006, accessed April 15, 2019 .

^ Christian Hülsmeyer. In: radartutorial.eu/. Retrieved April 16, 2019 .

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↑ Michael Ossenkopp: First traffic light in the world 150 years ago. In: stuttgarter-nachrichten.de. STN, December 7, 2018, accessed May 17, 2020 .

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↑ Patent EP0653073 : Electric Arc Detector. Published May 17, 1995 , inventor: Frederick K. Blades. ‌

↑ Patent EP0820651 : Arcing Fault Detection System. Published January 28, 1998 , Inventors: J. Stanley Brooks, James, W. Dickens, Walter H. Strader. ‌

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[1] William Gilbert: Tellure Tractatvs Siue Physiologia Nova De magnets Magneticisqve Corporibvs Et Magno magnets. Sex libris comprehensus . Online offer from the Herzog August Library Wolfenbüttel ( http://diglib.hab.de/drucke/nc-4f-46/start.htm ).

[:4-2] ↑ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k ^l ^m u. a. Andreas round: physical basics. In: Chronicle of electrical engineering from VDE-Verlag. VDE, April 3, 2017, accessed on May 8, 2020 .

[3] Electrical conductivity. In: uni-ulm.de. Ulm University, accessed on March 29, 2019 .

[4] u. a. Round Andreas: Chapter lightning. In: Chronicle of electrical engineering. VDE-Verlag, April 3, 2017, accessed on May 10, 2020 .

[5] Konrad Reichert and u. a .: electric motor and electric drives. In: Chronicle of electrical engineering. VDE, 2016, accessed on May 10, 2020 .

[6] Electrostatic application: telegraphy. In: uni-ulm.de. Ulm University, accessed on March 29, 2019 .

[7] Georg Christoph Lichtenberg (1742 to 1799). In: uni-goettingen.de. Georg-August-Universität Göttingen, accessed on March 29, 2019 .

[8] He knew how to combine plus and minus. In: rhetorik-netz.de/bio_lich/. Retrieved March 29, 2019 .

[9] May 2, 1800. In: funkzentrum.de. Retrieved March 25, 2019 .

[10] Henning Boëtius: History of electricity . 1st edition. Beltz & Gelberg, Germany 2006, ISBN 978-3-407-75326-7 .

[11] Early Wired Telegraphy. Harvard, September 18, 1999, accessed March 25, 2019 .

[12] Samuel Thomas von Sömmerring: Biography. The Engineering and Technology History Wiki (ETHW), February 26, 2016, accessed on March 25, 2019 .

[13] Francis Ronalds 1816. madeupinbritain.uk, July 5, 2017, accessed March 25, 2019 (English).

[:1-14] ↑ ^a ^b ^c ^d ^e ^f Martin Doppelbauer: The Invention of the Electric Motor 1800–1854: A Brief History of Electric Motor Technology - Part 1. In: eti.kit.edu. KIT, September 24, 2014, accessed on March 13, 2019 .

[15] A forgotten, versatile inventor - Baron Paul L. Schilling v. Canstatt. In: https://schilling-association.org/ . Association of the House of Schilling e. V., accessed on June 25, 2020 .

[:5-16] ↑ ^a ^b ^c ^d ^e ^f ^g Milestones: List of IEEE Milestones. In: https://ethw.org/ . Engineering and Technology History Wiki (ETHW), June 17, 2019, accessed on June 25, 2020 .

[17] Milestones: Shilling's Pioneering Contribution to Practical Telegraphy, 1828-1837. In: https://ethw.org/ . Engineering and Technology History Wiki (ETHW), May 18, 2009, accessed on June 25, 2020 .

[:3-18] Lenz, Heinrich Friedrich Emil. In: Personenlexikon.net. Retrieved April 23, 2019 .

[19] Dr. Lidia Łukasiak & Dr. Andrzej Jakubowski: History of Semiconductors (Science Paper). (PDF) In: https://djena.engineering.cornell.edu/ . Cornell University, January 1, 2010, accessed June 7, 2020 .

[20] Martin Doppelbauer (KIT): The invention of the electric motor 1800-1854: The first real electric motor of 1834. Part 3. In: eti.kit.edu. KIT: Karlsruhe Institute of Technology, January 8, 2018, accessed on March 14, 2019 (English).

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