A motor–generator is a device for converting electrical power to another form. Motor–generator sets are used to convert frequency, voltage, or phase of power, they may be used to isolate electrical loads from the electrical power supply line. Large motor–generators were used to convert industrial amounts of power while smaller motor–generators were used to convert battery power to higher DC voltages. While a motor–generator set may consist of distinct motor and generator machines coupled together, a single unit dynamotor has the motor coils and the generator coils wound around a single rotor; the motor coils are driven from a commutator on one end of the shaft, while the generator coils provide output to another commutator on the other end of the shaft. The entire rotor and shaft assembly is smaller and cheaper than a pair of machines, does not require exposed drive shafts. Low-powered consumer devices such as vacuum tube vehicle radio receivers did not use expensive and bulky motor–generators.
Instead, they used an inverter circuit consisting of a vibrator and a transformer to produce the higher voltages required for the vacuum tubes from the vehicle's 6 or 12V battery. In the context of electric power generation and large fixed electrical power systems, a motor–generator consists of an electric motor mechanically coupled to an electric generator; the motor runs on the electrical input current while the generator creates the electrical output current, with power flowing between the two machines as a mechanical torque. One use is motor–generator is to eliminate spikes and variations in "dirty power" or to provide phase matching between different electrical systems. Another use is to buffer extreme loads on the power system. For example, tokamak fusion devices impose large peak loads, but low average loads, on the electrical grid; the DIII-D tokamak at General Atomics, the Princeton Large Torus at the Princeton Plasma Physics Laboratory, the Nimrod synchrotron at the Rutherford Appleton Laboratory each used large flywheels on multiple motor–generator rigs to level the load imposed on the electrical system: the motor side accelerated a large flywheel to store energy, consumed during a fusion experiment as the generator side acted as a brake on the flywheel.
The next generation U. S. Navy aircraft carrier Electromagnetic Aircraft Launch System will use a flywheel motor–generator rig to supply power instantaneously for aircraft launches at greater than the ship's installed generator capacity. Motor–generators may be used for various conversions including: Alternating current to direct current DC to AC DC at one voltage to DC at another voltage. Creating or balancing a three-wire DC system. AC at one frequency to AC at another harmonically-related frequency AC at a fixed voltage to AC of a variable voltage AC single-phase to AC three-phase Before solid state AC voltage regulation was available or cost effective, motor generator sets were used to provide a variable AC voltage; the DC voltage to the generators armature would be varied manually or electronically to control the output voltage. When used in this fashion, the MG set is equivalent to an isolated variable transformer. An Alexanderson alternator is a motor-driven, high-frequency alternator which provides radio frequency power.
In the early days of radio communication, the high frequency carrier wave had to be produced mechanically using an alternator with many poles driven at high speeds. Alexanderson alternators produced RF up with large units capable of 500 kW power output. While electromechanical converters were used for long wave transmissions in the first three decades of the 20th century, electronic techniques were required at higher frequencies; the Alexanderson alternator was replaced by the vacuum tube oscillator in the 1920s. Motor–generators have been used where the input and output currents are the same. In this case, the mechanical inertia of the M–G set is used to filter out transients in the input power; the output's electric current can be clean and will be able to ride-through brief blackouts and switching transients at the input to the M–G set. This may enable, for example, the flawless cut-over from mains power to AC power provided by a diesel generator set; the motor–generator set may contain a large flywheel to improve its ride-through.
The in-rush current during re-closure will depend on many factors, however. As an example, a 250 kVA motor generator operating at 300 ampere of full load current will require 1550 ampere of in-rush current during a re-closure after 5 seconds; this example used. The motor–generator was a vertical type two-bearing machine with oil-bath bearings. Motors and generators may be coupled by a non-conductive shaft in facilities that need to control electromagnetic radiation, or where high isolation from transient surge voltages is required. Motor–generator sets have been replaced by semiconductor devices for some purposes. In the past, a popular use for MG sets were in elevators. Since accurate speed control of the hoisting machine was required, the impracti
Charles Proteus Steinmetz
Charles Proteus Steinmetz was a German-born American mathematician and electrical engineer and professor at Union College. He fostered the development of alternating current that made possible the expansion of the electric power industry in the United States, formulating mathematical theories for engineers, he made ground-breaking discoveries in the understanding of hysteresis that enabled engineers to design better electromagnetic apparatus equipment including electric motors for use in industry. At the time of his death, Steinmetz held over 200 patents. A genius in both mathematics and electronics, his work earned him the nicknames "Forger of Thunderbolts" and "The Wizard of Schenectady". Steinmetz's equation, Steinmetz solids, Steinmetz curves, Steinmetz equivalent circuit theory are all named after him, as are numerous honors and scholarships, including the IEEE Charles Proteus Steinmetz Award, one of the highest technical recognitions given by the Institute of Electrical and Electronics Engineers professional society.
Steinmetz was born Karl August Rudolph Steinmetz on April 9, 1865 in Breslau, Province of Silesia, Prussia the son of Caroline and Karl Heinrich Steinmetz. He was baptized a Lutheran into the Evangelical Church of Prussia. Steinmetz, who only stood four feet tall as an adult, suffered from dwarfism and hip dysplasia, as did his father and grandfather. Steinmetz attended Johannes Gymnasium and astonished his teachers with his proficiency in mathematics and physics. Following the Gymnasium, Steinmetz went on to the University of Breslau to begin work on his undergraduate degree in 1883, he was on the verge of finishing his doctorate in 1888 when he came under investigation by the German police for activities on behalf of a socialist university group and articles he had written for a local socialist newspaper. As socialist meetings and press had been banned in Germany, Steinmetz fled to Zürich in 1888 to escape possible arrest. Faced with an expiring visa, he emigrated to the United States in 1889.
He changed his first name to "Charles" in order to sound more American, chose the middle name "Proteus", a wise hunchbacked character from the Odyssey who knew many secrets, after a childhood epithet given by classmates Steinmetz felt suited him. Cornell University Professor Ronald R. Kline, the author of Steinmetz: Engineer and Socialist, contended that other factors were more directly involved in Steinmetz's decision to leave his homeland, such as being in arrears with his tuition at the University and life at home with his father and their daughters being tension filled. Despite his earlier efforts and interest in socialism, by 1922 Steinmetz concluded that socialism would never work in the United States, because the country lacked a "powerful, centralized government of competent men, remaining continuously in office", because "only a small percentage of Americans accept this viewpoint today". A member of the original Technical Alliance, which included Thorstein Veblen and Leland Olds, Steinmetz had great faith in the ability of machines to eliminate human toil and create abundance for all.
He put it this way: "Some day we make the good things of life for everybody". Steinmetz is known for his contribution in three major fields of alternating current systems theory: hysteresis, steady-state analysis, transients. Shortly after arriving in the United States, Steinmetz went to work for Rudolf Eickemeyer in Yonkers, New York, published in the field of magnetic hysteresis, which gave him worldwide professional recognition. Eickemeyer's firm developed transformers for use in the transmission of electrical power among many other mechanical and electrical devices. In 1893 Eickemeyer's company, along with all of its patents and designs, was bought by the newly formed General Electric Company, where Steinmetz became known as the engineering wizard in GE's engineering community. Steinmetz's work revolutionized AC circuit theory and analysis, carried out using complicated, time-consuming calculus-based methods. In the groundbreaking paper, "Complex Quantities and Their Use in Electrical Engineering", presented at a July 1893 meeting published in the American Institute of Electrical Engineers, Steinmetz simplified these complicated methods to "a simple problem of algebra".
He systematized the use of complex number phasor representation in electrical engineering education texts, whereby the lower-case letter "j" is used to designate the 90-degree rotation operator in AC system analysis. His seminal books and many other AIEE papers "taught a whole generation of engineers how to deal with AC phenomena". Steinmetz greatly advanced the understanding of lightning, his systematic experiments resulted in the first laboratory created "man-made lightning", earning him the nickname the "Forger of Thunderbolts". These were conducted in a football field-sized laboratory at General Electric, using 120,000 volt generators, he erected a lightning tower to attract natural lightning in order to study its patterns and effects, which resulted in several theories. Steinmetz acted in the following professional capacities: At Union College, as chair of electrical engineering from 1902 to 1913 and as faculty member thereafter until his death in 1923 As a board member on the Schenectady Board of Education for six years, including four years as the board's president As a president of the Common Council of Schenectady As the president of the AIEE from 1901 to 1902 As the first vice-president of the International Association of Municipal Electricians from 1913 until his death in 1923.
He was granted an honorary degree from Harvard Univer
A Scott-T transformer is a type of circuit used to produce two-phase electric power from a three-phase source, or vice versa. The Scott connection evenly distributes a balanced load between the phases of the source; the Scott three-phase transformer was invented by a Westinghouse engineer Charles F. Scott in the late 1890s to bypass Thomas Edison's more expensive rotary converter and thereby permit two-phase generator plants to drive three-phase motors. At the time of the invention, two-phase motor loads existed and the Scott connection allowed connecting them to newer three-phase supplies with the currents equal on the three phases; this was valuable for getting equal voltage drop and thus feasible regulation of the voltage from the electric generator. Nikola Tesla's original polyphase power system was based on simple-to-build two-phase four-wire components. However, as transmission distances increased, the more transmission-line efficient three-phase system became more common. Both 2 φ and 3 φ components coexisted for a number of years and the Scott-T transformer connection allowed them to be interconnected.
Assuming the desired voltage is the same on the two and three phase sides, the Scott-T transformer connection consists of a centre-tapped 1:1 ratio main transformer, T1, a √3/2 ratio teaser transformer, T2. The centre-tapped side of T1 is connected between two of the phases on the three-phase side, its centre tap connects to one end of the lower turn count side of T2, the other end connects to the remaining phase. The other side of the transformers connect directly to the two pairs of a two-phase four-wire system. Two-phase motors draw constant power, just as three-phase motors do, so a balanced two-phase load is converted to a balanced three-phase load; however if a two-phase load is not balanced, no arrangement of transformers can restore balance: Unbalanced current on the two-phase side causes unbalanced current on the three-phase side. Since the typical two-phase load was a motor, the current in the two phases was presumed inherently equal during the Scott-T development. In modern times people have tried to revive the Scott connection as a way to power single-phase electric railways from three-phase Utility supplies.
This will not result in balanced current on the three-phase side, as it is unlikely that two different railway sections, each connected as two-phase, will at all times conform to the Scott presumption of being equal. The instantaneous difference in loading on the two sections will be seen as an imbalance in the three-phase supply; the Scott-T transformer connection may be be used in a back-to-back T-to-T arrangement for a three-phase to three-phase connection. This is a cost-saving in the lower-power transformers due to the two-coil T connected to a secondary two-coil T instead of the traditional three-coil primary to three-coil secondary transformer. In this arrangement the X0 neutral tap is part way up on the secondary teaser transformer; the voltage stability of this T-to-T arrangement as compared to the traditional three-coil primary to three-coil secondary transformer is questioned, as the "per unit" impedance of the two windings are not the same in a T-to-T configuration, whereas the three windings are the same in a three transformer configuration, if the three transformers are identical.
Three-phase to three-phase distribution transformers are seeing increasing applications. The primary must be delta-connected, but the secondary may be either delta or "wye"-connected, at the customer's option, with X0 providing the neutral for the "wye" case. Taps for either case are provided; the customary maximum capacity of such a distribution transformer is 333 kV A. Alternating current Polyphase coil Symmetrical components High-leg delta
Alternating current is an electric current which periodically reverses direction, in contrast to direct current which flows only in one direction. Alternating current is the form in which electric power is delivered to businesses and residences, it is the form of electrical energy that consumers use when they plug kitchen appliances, televisions 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 used to mean alternating and direct, as when they modify current or voltage. The usual waveform of alternating current in most electric power circuits is a sine wave, whose positive half-period corresponds with positive direction of the current and vice versa. In certain applications, different waveforms are used, such as square waves. Audio and radio signals carried on electrical wires are examples of alternating current; these types of alternating current carry information such as sound or images sometimes carried by modulation of an AC carrier signal.
These currents alternate at higher frequencies than those used in power transmission. Electrical energy is distributed as alternating current because AC voltage may be increased or decreased with a transformer; this allows the power to be transmitted through power lines efficiently at high voltage, which reduces the energy lost as heat due to resistance of the wire, transformed to a lower, voltage for use. Use of a higher voltage leads to more efficient transmission of power; the power losses in the wire are a product of the square of the current and the resistance of the wire, described by the formula: P w = I 2 R. This means that when transmitting a fixed power on a given wire, if the current is halved, the power loss due to the wire's resistance will be reduced to one quarter; the power transmitted is equal to the product of the voltage. Power is transmitted at hundreds of kilovolts, transformed to 100 V – 240 V for domestic use. High voltages have disadvantages, such as the increased insulation required, increased difficulty in their safe handling.
In a power plant, energy is generated at a convenient voltage for the design of a generator, stepped up to a high voltage for transmission. Near the loads, the transmission voltage is stepped down to the voltages used by equipment. Consumer voltages vary somewhat depending on the country and size of load, but motors and lighting are built to use up to a few hundred volts between phases; the voltage delivered to equipment such as lighting and motor loads is standardized, with an allowable range of voltage over which equipment is expected to operate. Standard power utilization voltages and percentage tolerance vary in the different mains power systems found in the world. High-voltage direct-current electric power transmission systems have become more viable as technology has provided efficient means of changing the voltage of DC power. Transmission with high voltage direct current was not feasible in the early days of electric power transmission, as there was no economically viable way to step down the voltage of DC for end user applications such as lighting incandescent bulbs.
Three-phase electrical generation is common. The simplest way is to use three separate coils in the generator stator, physically offset by an angle of 120° to each other. Three current waveforms are produced that are equal in magnitude and 120° out of phase to each other. If coils are added opposite to these, they generate the same phases with reverse polarity and so can be wired together. In practice, higher "pole orders" are used. For example, a 12-pole machine would have 36 coils; the advantage is. For example, a 2-pole machine running at 3600 rpm and a 12-pole machine running at 600 rpm produce the same frequency. If the load on a three-phase system is balanced among the phases, no current flows through the neutral point. In the worst-case unbalanced load, the neutral current will not exceed the highest of the phase currents. Non-linear loads may require an oversized neutral bus and neutral conductor in the upstream distribution panel to handle harmonics. Harmonics can cause neutral conductor current levels to exceed that of all phase conductors.
For three-phase at utilization voltages a four-wire system is used. When stepping down three-phase, a transformer with a Delta primary and a Star secondary is used so there is no need for a neutral on the supply side. For smaller customers only a single phase and neutral, or two phases and neutral, are taken to the property. For larger installations all three phases and neutral are taken to the main distribution panel. From the three-phase main panel, both single and three-phase circuits may lead off. Three-wire single-phase systems, with a single center-tapped transformer giving two live conductors, is a common distribution scheme for res
An induction motor or asynchronous motor is an AC electric motor in which the electric current in the rotor needed to produce torque is obtained by electromagnetic induction from the magnetic field of the stator winding. An induction motor can therefore be made without electrical connections to the rotor. An induction motor's rotor can be either wound type or squirrel-cage type. Three-phase squirrel-cage induction motors are used as industrial drives because they are self-starting and economical. Single-phase induction motors are used extensively for smaller loads, such as household appliances like fans. Although traditionally used in fixed-speed service, induction motors are being used with variable-frequency drives in variable-speed service. VFDs offer important energy savings opportunities for existing and prospective induction motors in variable-torque centrifugal fan and compressor load applications. Squirrel cage induction motors are widely used in both fixed-speed and variable-frequency drive applications.
In 1824, the French physicist François Arago formulated the existence of rotating magnetic fields, termed Arago's rotations. By manually turning switches on and off, Walter Baily demonstrated this in 1879 the first primitive induction motor; the first commutator-free two phase AC induction motor was invented by Hungarian engineer Ottó Bláthy. The first AC commutator-free three-phase induction motors were independently invented by Galileo Ferraris and Nikola Tesla, a working motor model having been demonstrated by the former in 1885 and by the latter in 1887. Tesla applied for US patents in October and November 1887 and was granted some of these patents in May 1888. In April 1888, the Royal Academy of Science of Turin published Ferraris's research on his AC polyphase motor detailing the foundations of motor operation. In May 1888 Tesla presented the technical paper A New System for Alternating Current Motors and Transformers to the American Institute of Electrical Engineers describing three four-stator-pole motor types: one with a four-pole rotor forming a non-self-starting reluctance motor, another with a wound rotor forming a self-starting induction motor, the third a true synchronous motor with separately excited DC supply to rotor winding.
George Westinghouse, developing an alternating current power system at that time, licensed Tesla’s patents in 1888 and purchased a US patent option on Ferraris' induction motor concept. Tesla was employed for one year as a consultant. Westinghouse employee C. F. Scott was assigned to assist Tesla and took over development of the induction motor at Westinghouse. Steadfast in his promotion of three-phase development, Mikhail Dolivo-Dobrovolsky invented the cage-rotor induction motor in 1889 and the three-limb transformer in 1890. Furthermore, he claimed that Tesla's motor was not practical because of two-phase pulsations, which prompted him to persist in his three-phase work. Although Westinghouse achieved its first practical induction motor in 1892 and developed a line of polyphase 60 hertz induction motors in 1893, these early Westinghouse motors were two-phase motors with wound rotors until B. G. Lamme developed a rotating bar winding rotor; the General Electric Company began developing three-phase induction motors in 1891.
By 1896, General Electric and Westinghouse signed a cross-licensing agreement for the bar-winding-rotor design called the squirrel-cage rotor. Arthur E. Kennelly was the first to bring out the full significance of complex numbers to designate the 90º rotation operator in analysis of AC problems. GE's Charles Proteus Steinmetz developed application of AC complex quantities including an analysis model now known as the induction motor Steinmetz equivalent circuit. Induction motor improvements flowing from these inventions and innovations were such that a 100-horsepower induction motor has the same mounting dimensions as a 7.5-horsepower motor in 1897. In both induction and synchronous motors, the AC power supplied to the motor's stator creates a magnetic field that rotates in synchronism with the AC oscillations. Whereas a synchronous motor's rotor turns at the same rate as the stator field, an induction motor's rotor rotates at a somewhat slower speed than the stator field; the induction motor stator's magnetic field is therefore rotating relative to the rotor.
This induces an opposing current in the induction motor's rotor, in effect the motor's secondary winding, when the latter is short-circuited or closed through an external impedance. The rotating magnetic flux induces currents in the windings of the rotor, in a manner similar to currents induced in a transformer's secondary winding; the induced currents in the rotor windings in turn create magnetic fields in the rotor that react against the stator field. Due to Lenz's Law, the direction of the magnetic field created will be such as to oppose the change in current through the rotor windings; the cause of induced current in the rotor windings is the rotating stator magnetic field, so to oppose the change in rotor-winding currents the rotor will start to rotate in the direction of the rotating stator magnetic field. The rotor accelerates until the magnitude of induced rotor current and torque balances the applied mechanical load on the rotation of the rotor. Since rotation at synchronous speed would result in no induced rotor current, an induction motor always operates slower than synchronous speed.
The difference, or "slip," between actual and synchronous speed varies from about 0.5% to 5.0% for standard Design B torque curve induction motors. The induction mo
A rectifier is an electrical device that converts alternating current, which periodically reverses direction, to direct current, which flows in only one direction. The process is known since it "straightens" the direction of current. Physically, rectifiers take a number of forms, including vacuum tube diodes, mercury-arc valves, stacks of copper and selenium oxide plates, semiconductor diodes, silicon-controlled rectifiers and other silicon-based semiconductor switches. Synchronous electromechanical switches and motors have been used. Early radio receivers, called crystal radios, used a "cat's whisker" of fine wire pressing on a crystal of galena to serve as a point-contact rectifier or "crystal detector". Rectifiers have many uses, but are found serving as components of DC power supplies and high-voltage direct current power transmission systems. Rectification may serve in roles other than to generate direct current for use as a source of power; as noted, detectors of radio signals serve as rectifiers.
In gas heating systems flame rectification is used to detect presence of a flame. Depending on the type of alternating current supply and the arrangement of the rectifier circuit, the output voltage may require additional smoothing to produce a uniform steady voltage. Many applications of rectifiers, such as power supplies for radio and computer equipment, require a steady constant DC voltage. In these applications the output of the rectifier is smoothed by an electronic filter, which may be a capacitor, choke, or set of capacitors and resistors followed by a voltage regulator to produce a steady voltage. More complex circuitry that performs the opposite function, converting DC to AC, is called an inverter. Before the development of silicon semiconductor rectifiers, vacuum tube thermionic diodes and copper oxide- or selenium-based metal rectifier stacks were used. With the introduction of semiconductor electronics, vacuum tube rectifiers became obsolete, except for some enthusiasts of vacuum tube audio equipment.
For power rectification from low to high current, semiconductor diodes of various types are used. Other devices that have control electrodes as well as acting as unidirectional current valves are used where more than simple rectification is required—e.g. Where variable output voltage is needed. High-power rectifiers, such as those used in high-voltage direct current power transmission, employ silicon semiconductor devices of various types; these are thyristors or other controlled switching solid-state switches, which function as diodes to pass current in only one direction. Rectifier circuits may be multi-phase. Most low power rectifiers for domestic equipment are single-phase, but three-phase rectification is important for industrial applications and for the transmission of energy as DC. In half-wave rectification of a single-phase supply, either the positive or negative half of the AC wave is passed, while the other half is blocked. Mathematically, it is a step function: passing positive corresponds to the ramp function being the identity on positive inputs, blocking negative corresponds to being zero on negative inputs.
Because only one half of the input waveform reaches the output, mean voltage is lower. Half-wave rectification requires a single diode in a single-phase supply, or three in a three-phase supply. Rectifiers yield a pulsating direct current; the no-load output DC voltage of an ideal half-wave rectifier for a sinusoidal input voltage is: V r m s = V p e a k 2 V d c = V p e a k π where: Vdc, Vav – the DC or average output voltage, the peak value of the phase input voltages, the root mean square value of output voltage. A full-wave rectifier converts the whole of the input waveform to one of constant polarity at its output. Mathematically, this corresponds to the absolute value function. Full-wave rectification converts both polarities of the input waveform to pulsating DC, yields a higher average output voltage. Two diodes and a center tapped transformer, or four diodes in a bridge configuration and any AC source, are needed. Single semiconductor diodes, double diodes with common cathode or common anode, four-diode bridges, are manufactured as single components.
For single-phase AC, if the transformer is center-tapped two diodes back-to-back can form a full-wave rectifier. Twice as many turns are required on the transformer secondary to obtain the same output voltage than for a bridge rectifier, but the power rating is unchanged; the average and RMS no-load output voltages of an ideal single-phase full-wave rectifier are: V
Galileo Ferraris was an Italian physicist and electrical engineer, one of the pioneers of AC power system and an inventor of the three-phase induction motor. Many newspapers touted that his work on the induction motor and power transmission systems were some of the greatest inventions of all ages, he published an extensive and complete monograph on the experimental results obtained with open-circuit transformers of the type designed by the power engineers Lucien Gaulard and John Dixon Gibbs. Born at Livorno Vercellese, Ferraris gained a master's degree in engineering and became an assistant of technical physics near the Regal Italian Industrial Museum. Ferraris independently researched the rotary magnetic field in 1885. Ferraris experimented with different types of asynchronous electric motors; the research and his studies resulted in the development of an alternator, which may be thought of as an alternating-current motor operating in reverse, so as to convert mechanical power into electric power.
On 11 March 1888, Ferraris published his research in a paper to the Royal Academy of Sciences in Turin. These alternators operated by creating systems of alternating currents displaced from one another in phase by definite amounts, depended on rotating magnetic field for their operation; the resulting source of polyphase power soon found widespread acceptance. The invention of the polyphase alternator is key in the history of electrification, as is the power transformer; these inventions enabled power to be transmitted by wires economically over considerable distances. Polyphase power enabled the use of water-power in remote places, thereby allowing the mechanical energy of the falling water to be converted to electricity, which could be fed to an electric motor at any location where mechanical work needed to be done; this versatility sparked the growth of power-transmission network grids on continents around the globe. In 1889, Ferraris worked at a school of electrical engineering. In 1896, Ferraris joined the Italian Electrotechnical Association and became the first national president of the organization.
Galileo Ferraris did not confine his research interests to electricity. He researched the fundamental properties of dioptric instruments and made elementary representation of the theory and its applications, his work contains a detailed description of the geometric dioptrics for uncentered systems. He provided a greater generality as found in the telescopic system treatments, with less emphasis on applications. In the second main sections, the results obtained; the magnification, field of view, the brightness of the instrument were dealt with in great detail. The field denned as the author of the cone opening angle, the tip of the first main points of the lens, its base formed by the parts of the object in view, will possess the same brightness; the eye is not treated. The city of Turin honored the contributions. A general committee proposed an addition to the Royal Industrial Museum of Turin with a permanent monument commemorating his scientific and industrial achievements. Additionally, an avenue was named in honor of Ferraris.
Sulle differenze di fase delle correnti e sulla dissipazione di energia nei trasformatori, by Prof. Galileo Ferraris. Le proprietà cardinali degli strumenti ottici. Roma: Loescher. 1877. Wissenschaftliche Grundlagen der Elektrotechnik. Leipzig: Teubner. 1901, by G. Ferraris, trans. from the original Italian into German by Leo Finzi Opere di Galileo Ferraris, pubblicate per cura della Associazione elettrotecnica italiana. 3 vols. Milano: Ulrico Hoepli. 1902–1904. Online texts: vol. 1 vol. 2 vol. 3 Dibner, Bern. "Ferraris, Galileo". Dictionary of Scientific Biography. 4. New York: Charles Scribner's Sons. Pp. 588–9. ISBN 978-0-684-10114-9. Katz, Eugenii, "Galileo Ferraris". Biosensors & Bioelectronics. Istituto Elettrotecnico Nazionale Galileo Ferraris – Official web site Physicist, Pioneer of Alternating Current Systems Who Invented the Polyphase Electric Motor