1 transformer-prototype of induction coil
1888, the famous British physicist J.A.Fleming (1849- 1945) clearly said at the beginning of his masterpiece AC Transformer: "Faraday and Henry are two prominent investigators standing on the head of this long line of absurd investigators. The cornerstone of truth. All the subordinate builders laid by them have been content to rest "(among a large number of outstanding people who study Transformers, the leaders are giants Faraday and Henry, who laid the cornerstone of truth, and all the latecomers are committed to the completion of the building).
Therefore, to trace the history of the invention of transformers, we have to start with Faraday and Henry.
183 1 On August 29th, Faraday conducted a magnetic energy power generation experiment with the experimental device shown in Figure 1. In figure 1, the circular ring is made of 7/8 inch iron bars, and the outer diameter of the circular ring is 6 inches; A is a coil formed by winding three 24-foot-long copper wires (the three sections can be connected in series as required); B is two coils made of 50-foot copper wire (two coils can be connected in series); 1 is the battery; 2 is a switch; 3 is a current detector. In the experiment, when the switch 2 is closed, Faraday finds that the current detector 3 swings, that is, there is current flowing in the coil B and the current detector 3. In other words, Faraday discovered electromagnetic induction through this experiment. Faraday's device (Faraday induction coil, Figure 2) used in this experiment is actually the first prototype transformer in the world. Later, Faraday did several experiments, and on June 28th of the same year 10, the first disc DC generator was made. In the same year,165438+1October 24th, Faraday reported his experiments and discoveries to the Royal Society, which made Faraday recognized as the discoverer of electromagnetic induction phenomenon, and he naturally became the inventor of transformer.
But in fact, Henry, a famous American scientist, was the first person to invent the transformer. 1830 In August, Henry, then a professor at Orbant College in new york, used the vacation time of the college to conduct an experiment of magnetic energy power generation with the experimental device shown in Figure 3. When he closed the switch K, he found that the pointer of galvanometer P was swinging. Turn on the switch K and find that the pointer of galvanometer P swings in the opposite direction. In the experiment, when the switch K is turned on, Henry also observed that there is a spark between the two ends of the coil B. Henry also found that by changing the turns of the coils A and B, a high-intensity current can be turned into a small amount of current, and a small current can also be turned into a large current. In fact, Henry's experiment is a very intuitive key experiment of electromagnetic induction phenomenon, and Henry's experimental device is actually a prototype of a transformer. However, Henry is very cautious. He is in no hurry to announce the results of his experiment. He wants to do more experiments. However, the holiday has passed, so he has to put it aside. Later, he conducted many experiments until 1832, and his experimental paper was published in the seventh issue of American Journal of Science and Art. But before that, Faraday first published his electromagnetic induction experiment and introduced his experimental device, so the invention right of electromagnetic induction phenomenon can only belong to Faraday, and the invention right of transformer is also illegal. Although Henry unfortunately missed the discovery right of electromagnetic induction and the invention right of transformer, his contribution to electricity and transformer invention is obvious to all. It is particularly worth mentioning that Henry experimental device is closer to modern universal transformer than Faraday induction coil.
Firstly, his electromagnetic induction experiment was announced and his experimental device was introduced. Therefore, the invention right of electromagnetic induction can only belong to Faraday, and the invention right of transformer is also illegal. Although Henry unfortunately missed the discovery right of electromagnetic induction and the invention right of transformer, his contribution to electricity and transformer invention is obvious to all. It is particularly worth mentioning that Henry experimental device is closer to modern universal transformer than Faraday induction coil. ?
According to the principle of modern transformer, Faraday induction coil is a single-core closed magnetic circuit double-winding transformer. Because there was no AC power supply at that time, it was an original pulse transformer, while Henry transformer was an original double-core open-circuit magnetic circuit double-winding pulse transformer.
1835, American physicist Page (C.J. Page, 18 12 ~ 1868) made the induction coil as shown in Figure 4. This coil is the first autotransformer in the world. It uses the vibration of an automatic hammer to make mercury connect or disconnect the circuit. The electromotive force induced in the secondary coil can cause an electric spark in a 4.5-inch-long vacuum tube.
1837, the British priest N.J.Callan divided the Page transformer into two parts without electrical connection (Figure 5). When the switch M is turned on and the circuit of the coil A is turned off, a spark will be generated between the two ends of the coil B..
Like Faraday's and Henry's transformers, Page's and Kahlan's transformers are devices that work on intermittent DC, which can only be used for experimental observation and have no practical application value.
German technician H.D. kolff (1803 ~ 1877) is a great contributor in the history of transformer invention. He was born in Germany, and later settled in Paris, and established his own precision machinery manufacturing workshop. Rum kolff didn't make any achievements in theory, but he was good at studying other people's suggestions and put them into practice with his intelligence, and made some excellent induction coils. 1842, under the guidance of Masson and Brequet, research on Kalan transformer was started. The first induction coil was made in 1850. 185 1 year, he put forward the first patent of induction spark coil (transformer). Rum kolff induction coils are shown in figs. 6 and 7. The iron core is made of soft iron wire, the primary coil is wound on the iron core, and the secondary coil is wound on the primary coil. The primary coil is powered by the storage battery, and the mercury switch is repeatedly turned on and off through the magnetized iron core mechanism, so that the primary coil is repeatedly changed in direction by pulsating DC. Alternating current is induced in the secondary coil. Compared with the previous induction coil, Rum kolff induction coil has been greatly improved. First of all, the insulation of the secondary coil is more reliable. The coil is wound with enameled copper wire, the coil layer is insulated with paper or paint, and the secondary coil and the primary coil are separated by glass tubes. Secondly, Rum kolff used the inventions of E.English and C.Bright to divide the secondary coil into several sections, separate them from each other, and then string them together. This can make the distance between the points with the largest potential difference (outlet terminals S-S) farthest. Later, Rum kolff improved the coil, such as changing the mercury switch used before into an alcohol switch, which can not only eliminate the switching spark, but also prevent oxidation; In addition, he connected a capacitor to the primary coil to increase the induced voltage. Because of its high power, Rum kolff coil can be used not only for experiments, but also for discharge therapy. So it can be said that Rum kolff induction coil is the first transformer with practical value.
In order to get a bigger spark, 1856, the British electrician Varley (1828 ~ 1883) also improved the Kalan transformer. He used a double-pole, double-throw switch to change the direction of current back and forth, so that the current in coil A changed direction alternately, and an alternating current was induced in coil B. In 1862, Morris, Weave and Moncktom obtained the patent of using the induction coil to generate alternating current.
1868, the British physicist Grove (W.R. Grove,181~1896) connected the AC power supply V to the coil A with the device shown in Figure 9, and obtained AC currents with different voltages in the coil B, so Grove.
After Grove, many people studied the induction coil and put forward some suggestions for improvement. For example, J.B.Fuller, an American, made a theoretical study on the induction coil in the early 1970s from 65438 to 2009, and proposed that the induction coil should adopt a closed iron core, and the primary coil should be connected in parallel instead of in series as most induction coils used at that time. But his thoughts were only discussed with his boss before his death, until his manuscript was discovered shortly after his death. 1879 In February, people compiled and published his manuscript, and his ideas about induction coils were made public.
1876, Russian physicist yablokhkov (лняълочков, 1847 ~ 1894). This induction coil is actually a single-phase transformer with no closed core.
1882, Russian engineer иФ Usagin exhibited the high-voltage transformer with step-up and step-down induction coils for the first time in Moscow.
2 Gorland-Gibbs secondary generator
19 After the 1980s, alternating current entered human social life, and the principle of transformers was also understood by many people. People naturally think of using transformers in actual AC circuits. France's L. Gaulland (1850 ~1888) and Britain's J.D.Gibbs took the lead in this respect and made great contributions. 1882 12 On September 3rd, they applied for the first patent (.4362) of induction coil and its power supply system in Britain, and they called this kind of induction coil a "secondary generator". Figure 12 is a schematic diagram of the Gorland-Gibbs secondary generator. The ratio of the number of primary windings to the number of secondary windings is 1: 1. The primary winding is connected in series, and the secondary winding is divided into several sections, which are respectively connected to the electric lamp 1. Gorland-Gibbs secondary generator (transformer) is an open-circuit core transformer, which controls the voltage by pushing and pulling the core. For the primary coil, they still insist on series connection (although Maxwell proved in 1865 that if the primary coil is connected in series, the secondary voltage cannot be controlled separately).
1882, 100 10. On October 7th, they made the first 3000V/ 100V secondary generator, 1983, they made a secondary generator with a capacity of about 5kVA, a small electrician outside London. At that time, they provided several small transformers for the London City Railway. 1884, they exhibited their transformers in Turin, Italy, and conducted AC long-distance transmission. Open magnetic circuit transformer series AC transmission system is adopted to transmit 30kW, 133Hz AC power to a distance of 40km. They also sold several similar transformers in those years, which were experimental transformers sold to Italian physicist ferraris (1847 ~ 1897). Transformer iron core is an open-circuit iron core composed of iron wire. The primary coil consists of 445 turns (turns) wound with 0.25mm thick copper sheet, but they are divided into four sections in the height direction. The four sections of the secondary coil are connected in series or in parallel through the front plug, thus changing the output voltage of the secondary coil. Another high Rand-Gibbs secondary generator, this secondary generator can change the output power by adjusting the output voltage.
1884 On March 4th, Gorland and Gibbs applied for the first patent (.297924) "Device for Generating and Utilizing Secondary Current" in the United States.
1885, Gorland and Gibbs were inspired by the transformer in Guntz factory to study the transformer with closed-circuit iron core structure. 1886 On March 6th, they applied for the patent of closed magnetic circuit transformer in the United States (.351589). 1886 closed-circuit iron core Gorland-Gibbs secondary generator.
Ziborowski-Delhi-Blache (Z-D-B) Transformer
Although Gorland-Gibbs secondary generator (transformer) has opened up the practical application field of transformer, there are some inherent shortcomings in the early stage, such as open core and series connection of primary winding. Three young engineers Blache (O.T. Blathy, 1860 ~ 1939) and C. Zipernowsky (1853 ~1942) from Ganz factory in Hungary first questioned this and improved it.
Blache entered the Gonz factory on 1883 and served as technical director for a long time. He made many inventions in his life and obtained more than 100 patents, including transformers, voltage regulators, turbo-generators, etc. Blache was one of the first people to study the parallel operation of alternators, and he also invented many motor design programs and design calculation methods. In addition, he first introduced the word "transformer" in 1885. This concise and vivid term was quickly recognized and accepted by people, and soon replaced the previous terms such as "induction coil" and "secondary generator", which have been used ever since.
Zibonovsky is one of the founders of the electrical department of Gunz Factory, which was established in 1878. From 65438 to 0893, he was appointed professor of electricity at Budapest Technical University in Hungary. He has obtained more than 40 patents in his life and served as the chairman of the Hungarian Institute of Electrician for 30 years.
Delhi joined the Gonzalez factory at 1882. He has worked in the sales department for a long time, but he knows a lot about motors and transformers. He once designed a compound excitation alternator and invented a double-brush repulsion motor named after him-Delhi Motor.
1884, held in Turin, Italy. A group of technicians from Blache and Gonz factories visited the Expo and saw the Gorland-Gibbs secondary generator on display. At that time, Blache was keenly aware of the huge development prospect of this kind of secondary generator and noticed the advantages and disadvantages of this kind of transformer. At the Expo, blache once asked Gao Lande, "Why doesn't your secondary generator use a closed-circuit iron core?" Gao Lande replied without thinking: "It is dangerous and uneconomical to use closed-circuit iron core."
1in July, 884, after blache returned to Budapest from Turin, he immediately told Zyborowski and Dari what he had seen and heard at the Turin Expo, and they decided to carry out transformer improvement experiments immediately. Blache suggested using closed-circuit iron core, Zibnovsky suggested changing the series connection of primary winding into parallel connection, and conducted research experiments with Delhi. 1on August 7th, 884, they introduced the transformer with closed magnetic circuit core in the experimental magazine of the Gunz factory (figure 18).
1In the winter of 884, Delhi showed their invention at the Vienna Trade Federation. 1885 65438+1On October 2nd, Zibernowski and Delhi applied for the first patent on parallel operation of transformers in Austria (.37/101). On February 2nd of the same year, the three of them applied for the second transformer patent in Austria and Germany (Austrian patent .35/2446 and German patent .40414).
1884 The first transformer (1400W, f=Hz, 120/72V, transformation ratio 1.67) manufactured by Gonz Factory was a single-phase shell closed-circuit iron core (iron wire) transformer. In the same year, Gonz factory also manufactured four other transformers.
May 1885, 1, Hungary's Brapes National Expo opened. The current generated by a single-phase alternator of 150V and 70Hz was stepped down by 75 5kVA transformers (closed-core, parallel connection and shell type) in Gonzalez factory, which lit up 1067 Edison bulbs in the Expo venue, which was spectacular. Therefore, people later commemorated 1 May 8851day as the birth day of modern practical transformers. The Budapest Expo made the Ganci factory famous all over the world, and the factory received a batch of orders during the Expo.
Ziberovsky-Delhi-Blache (Z-D-B) transformer is an important milestone in the development history of transformer technology, and its basic structure, such as closed-circuit iron core and primary-side parallel connection, has been used up to now. It can be said that Z-D-B transformer has basically shaped the structure of modern transformers, and since then, transformers have officially entered the field of AC current transmission and distribution, which has effectively promoted the popularization and application of AC current and promoted the development of modern AC motors.
1888, Ganci factory transferred the patent right of transformer to Siemens-Halske company. Soon, two other German companies also bought the transformer patent right of Gonzalez factory. 1890, French and Spanish companies also bought the patent of Ganci transformer. Since the late 1980s of 19, transformers have been widely used in Europe. By 1889, a total of 1000 transformers were produced, and by 1899, the number has exceeded 10000. Before the 1920s, Gonzalez Factory maintained the world leading level in the field of transformer manufacturing.
The spread and development of transformer technology in America?
65438+At the beginning of 1980s, when Europeans were trying to improve transformers and explore the application fields of transformers, the American Edison Company on the other side of the ocean was intoxicated with the success of DC system and the huge profits it brought, but ignored AC system and transformers. But at this time, Westinghouse (W. Westinghouse, 1846 ~ 19 14), which started with train air braking, is trying to set foot in the field of communication. 1885 In the spring, he roamed Europe, visited London and Budapest, and was also in contact with European inventors at that time. He was very interested in Gorland-Burgis secondary generators and immediately decided to buy several secondary generators. 1885 in may, Pantaleoni, a young engineer of Westinghouse air brake company, returned to Italy to attend the funeral because of his father's death. When he visited his university teacher in Turin, he met Gorland who was at the Turin Technology Expo. At that time, Gao Lande was installing the communication system between Lanzuo and Circe. Pantalenli was very interested in this and immediately sent a telegram to Westinghouse to report his impression. Westinghouse attached great importance to it, called Pantaleni back and asked him to contact Gaolan Company to purchase the exclusive rights of transformers applied by Gaolan Company and Gibbs Company in the United States. After friendly negotiation, Gorland agreed to Westinghouse's request.
On September 1885 and 1, the Jin Lan-Gibbs secondary generator ordered by Westinghouse Air Brake Company and the single-phase alternator of Siemens Company were shipped from Europe to the United States.
1885165438+1On October 23rd, R.Belfield arrived in Pittsburgh, USA as the authorized representative of Goldland-Gibbs Company, transferred the transformer technology to Westinghouse Air Brake Company, and helped the company design a new type (closed-circuit iron core) transformer. 1886 65438+1On October 5th, he went to Barrington to help W.Stanley (then an assistant of Westinghouse) with the construction. Run the 3000 volt AC transmission line in Burlington. 1March 20th, 886, the first AC transmission line in the United States was completed and put into operation, marking the real beginning of the American electrical era!
Westinghouse not only attracts talents, buys patents, orders equipment, develops AC systems and transformers with the courage of industrialists, but also devotes itself to the research of transformers. 1886 65438+1October 8th, he founded westinghouse Electric Company, which made great strides in the electrical field (mainly alternating current) and officially entered the research and industrial production of transformers. 1886 filed two American patents (.342552 and .34553) for power distribution system and closed-circuit core transformer in February. Figure 23 shows Westinghouse's earliest transformer. 1888, Westinghouse manufactured 40 2kW lamp transformers. 189 1 year, Westinghouse manufactured the first oil-filled transformer (voltage 10kV) (Figure 24).
In sharp contrast to Westinghouse's active exploration and development of transformer industry, Edison's indifference and short-sighted attitude towards transformers. At that time, Edison Electric's electric lights and DC generators dominated the North American continent and were exported to Europe. Edison was full of ambition, dismissive of the emerging AC power supply system, and a little hostile (which planted the seeds for the future AC -DC war in the United States). 1885, J.W.Lieb, the representative of Edison Company, visited the Turin Expo and saw the AC distribution system and transformers on display. But Li Bo, like Edison, was a diehard DC radical. He made a report to Edison, reported his impressions, and criticized the AC distribution system and transformers exhibited at the meeting. This report also strengthened Edison's determination to oppose alternating current. 1886, blache went to America and met Edison. The two sides signed an agreement, and Edison invested $20,000 to purchase the exclusive patent right of the transformer applied by the Gonz factory in the United States. However, Edison didn't want to develop AC systems and transformers at all. Signing this agreement is just a strategy for other companies to develop AC systems and transformers. Therefore, the direct consequence of this paper agreement is to hinder the popularization and application of Z-D-B transformer in the United States. This situation was not fundamentally changed until 1892 when Edison merged into General Electric Company.
In the history of transformer development in the United States, two other people also made indelible contributions. They are Stanley (W. Stanley, 1856 ~ 1927) and Stella (N. Tesla, 1856 ~ 1943).
Stanley began to contact AC at 1883, and had a profound discussion on the role of transformer in AC system. He called the transformer "the heart of the AC system" many times. From 1883 to 1884, he studied transformers in his small laboratory. 1In February, 884, he was employed by Westinghouse Company as his assistant, presiding over the design and manufacture of AC system and transformer. 1On September 29th, 885, the first transformer (Figure 25) with primary windings connected in parallel and closed magnetic circuit core in the United States was manufactured and tested in the workshop of Westinghouse Air Brake Company. 1885, 10 year123 October, filed the first patent on closed-circuit core transformer in the United States (.49612); In the same year 1 65438+1October 23rd, he put forward three patents, including two patents for power distribution system of transformers (.372943 and .372944) and one patent for open-circuit core transformer1(.3738+060). 1885 65438+In February, he presided over the construction of the first AC transmission system in the United States-the AC transmission system in Grand Linto. On March 20th, 1886, the system was completed and put into operation. 1890 left Westinghouse electric company. 189 1 year, he established Stanley electric manufacturing company in Pittsfield and continued to develop transformers. Fig. 26 shows a commercial transformer of Stanley Company. 189 1 year Stanley made a 25kVA commercial transformer. 1892, Stanley developed 15kV transformer, which made the AC transmission voltage in the United States break through 10kV in one fell swoop, thus opening the door to high-voltage transmission. Stanley also won the reputation of "the father of electric drive". 1903, merging the company into GE company. At GE company, he continued to guide GE company to develop transformers. Therefore, Westinghouse and GE's early transformer technologies are in the same strain, and both adopt shell-type transformer structures. They didn't go their separate ways until 19 18 Ge changed its core.
Tesla is an American Croatian scientist known as "electrician genius", and his contribution to AC system and AC motor is world-famous. 1888 was employed by Westinghouse and made great achievements in transformer. 1890 left Westinghouse to start his own business and continue to study transformers. Fig. 28 is the principle of Tesla high-frequency transformer invented by 189 1, and fig. 29 is the recovery diagram of Tesla high-frequency transformer. The primary winding of the transformer is 12 turns of φ5mm copper wire, which is wound on a 55mm glass tube. The secondary coil has 380 turns and 0.2mm copper wire, which is wound on φ 1 13 mm glass tube. The primary and secondary coils are placed in a glass tube with a height of 50cm and an inner diameter of φ 16.5cm and immersed in insulating mineral oil. When the primary coil is connected to the oscillation circuit, the high frequency current of 105 ~ 106 Hz can be obtained at both ends of the secondary coil, and obvious sparks can be observed. This transformer has been used to study the phenomenon of high frequency electric oscillation, and the skin effect has been observed through it.
The birth of three-phase transformer
Gorant-Gibbs secondary generator and Z-D-B transformer are both single-phase transformers. Russian scientist Dolivo-Dobrovski, who is known as the "father of three-phase alternating current", invented the three-phase transformer. 1888, he proposed that three-phase current can generate rotating magnetic field, and invented three-phase synchronous generator and three-phase squirrel-cage motor. 1889, in order to solve the problem of three-phase current transmission and power supply, he began to study three-phase transformers. Compared with the single-phase transformer at that time, there is not much difference between the primary winding and the secondary winding of the D-Dolivo-Dobrovski three-phase transformer, and the main difference lies in the arrangement of iron cores. At that time, he applied for the patent ofNo. 1 three-phase transformer core. The three core columns are vertically and symmetrically arranged along the circumferential direction, and the upper and lower parts are connected by two yoke rings. This structure is similar to the monasteries in medieval Europe, so it is called "Tempeltype", as shown in Figure 30(a). As shown in fig. 30(b) and fig. 30(c), a "temple-like" structure was later developed. In 189 1, Siemens first adopted the frame core, as shown in Figure 30(d).
The world's first three-phase transformer appeared in 189 1. In August that year, the World Expo was held in Frankfurt, Germany. In order to demonstrate the transmission and application of alternating current, the organizer installed a set of three-phase hydro-generator set (2 10kVA, 175km/min, 445 km away) in Portland Cement Plant in Lao Fen. Therefore, the German General Electric Company (AEG) and the Swiss Oerlikon factory provided four three-phase transformers and two three-phase transformers for the Lao Fen-Frankfurt project respectively. In Lao Fen, AEG company provides two three-phase step-up transformers (each 100kVA, transformation ratio 1: 160, Y-Y wiring), and Oricon factory provides one step-up transformer (150kVA, transformation ratio1:60). The two step-down substations in Frankfurt are respectively equipped with two three-phase step-down transformers (ratio 123: 1) produced by AEG to supply power to the motor, and one three-phase step-down transformer (ratio11) produced by Oricon Factory to supply power to the motor. The highest efficiency of the tested transformer reaches 96%. Figure 3 1 shows the three-phase transformer produced by AEG company.
6 Other Transformers?
In addition to the above-mentioned Transformers, at the end of 19 and the beginning of the 20th century, many people made various Transformers, which made the early Transformers colorful and accumulated valuable experiences and lessons for the later development of various Transformers.
British scientist ferrante (1864 ~ 1930) studied transformers, and in 1885, he obtained a patent on closed magnetic circuit transformers. 1888, a transformer with iron sheet bent into a circle to form an iron core was developed (fig. 32). 189 1 year, a large-capacity transformer with 10kV/2kV was manufactured. Its core consists of 10 sections, each section of core consists of circular iron sheets, and the gap between sections is used for ventilation and heat dissipation (Figure 33).
1884, British electrician J Hopkinson (1849 ~ 1898) and his younger brother E Hopkinson (1859 ~ 1922) applied to close the magnetic circuit.
189 1 year, M.W.Mordey designed and manufactured a laminated core transformer for Blache company (fig. 34).
American electrician e Thomson (1853 ~ 1937) studied transformers at Franklin college as early as 1879. 1886, he made the first welding transformer, the secondary winding of which was single turn, and soon he made a constant current transformer (Figure 35).
Disk and R. Kennedey invented a transformer structure with an H-shaped iron core (Figure 36).
1889, Swinburne invented the "Hedgehog" oil-immersed transformer, which is still in use today.
In addition, in the 1980s and 1990s of 19, there were other people who studied transformers, such as Mason, Feldman, W. sturgeon, J.A Fleming, the son of W. B. Said, I. Chenat, G. Felaez, R. Rhulman, W. Peckett and K. Zicci. E. Hospital, F. Uppenborn, A. Urbanitzky, R. E. Crompton, K. D. Mackenzie, G. Forbes, S. straub, F. Wilkin, M. A.A. Roiti, M. Swinburne, Kittler, etc.
References:
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