Over the years, the electrical machines are very popularly used for many applications. The AC static electrical machines, namely transformers, are used to step up and step down voltage level in power systems. Also, transformers are used to provide electrical isolation in electronics applications. Motors are used in domestic applications such as water pumps, grinders, mixers, washing machines and many more. Also, motors find applications in commercial/industrial applications such as automation and control industries, which include paper mills, centrifuge [1] etc. The generators are used to supply electrical power. The major revolution in the electrical machines took place during 19th century. Many articles on history of electrical machines have been reported in the literature [2-6]. However, this short report is presented in a way that would help budding electrical engineers to understand the major & significant historical evolution of various electrical machines in a quicker way – and also this article would make the students develop interest on electrical machines course after reading it.
History of Generators
In Early 1830s, three scientists namely Oersted, Gauss and Faraday worked on the Principle of Electromagnetic Induction independently. But, Michel Faraday is the one who exploited the use of electromagnetic induction principle in 1831 – and based on the electromagnetic principle, he developed his first prototype model of generator and named that “Faraday Disk Generator”. The representation of Faraday’s disk generator is shown in figure 1. The prototype model consisted of a permanent magnet, which forms north and south pole, copper disc with handle and a galvanometer. Faraday rotated the copper disc with the help of a handle in presence of magnetic field, which was created by the permanent magnet. As the disc was rotated, he observed deflection in the galvanometer. Through this experimental set up, he showed that whenever the conductor cuts the magnetic field, emf is induced in the conductor and the current flows through the closed circuit that is observed as deflection in the galvanometer.
Later, German scientist Werner Von Siemens improved the design of DC generators developed by Faraday and called them Dynamos – and possibly he might have got higher voltage than that in the case of Faraday disk generator. In olden days, we could see dynamos in the bicycles to electrify lamps in the cycle. Then in the year 1867, better generator was introduced by a French scientist named Zénobe-Théophile Gramme, which produced substantially higher voltages than previous attempts. In the year 1872, Von Siemens developed a more efficient design for generators. Till this point of time, generators developed were not used for practical applications.
In the late 1870s, Thomas Alva Edison devised his highly successful electric lighting system with DC generators. In 1882, Edison installed DC generators at the Pearl Street station in New York city, it was one of the earliest commercial power generating plants. The DC generator and DC power generating station developed by Edison are shown in Figure 2 and Figure 3 respectively. Edison was the first man to showcase the practical use of DC generators. In that period, both DC and AC generators were available. The only difference between DC and AC generator is that the DC generator has split ring or commutator and the AC generator has slip ring. Edison wanted to use generator for dual practical purposes, one is to electrify the Pearl Street and another one to run the motor. As only DC motors were available at that time, Edison made use of DC generators to provide DC electrical power to the DC motors. People lived in Pearl Street might have been happy to enjoy the luxury of electricity from the power station developed by Edison. But the people who were living in other areas also had to get electricity. But the problem with DC generator was that the DC power generated using DC generators could not be transmitted over longer distances, as it led to severe power loss. Hence, it was not possible to provide electricity for the people living in the places which were far away from the Edison’s power station. In that period, transformers were developed. The brief history of transformers is dealt in the next section.
History of Transformers
In 1830s, Joseph Henry and Michael Faraday worked with electromagnets and discovered the property of mutual induction independently on separate continents. In 1885 and 1886, William Stanley built more practical single phase transformers. Stanley’s first transformer was used in the electrification of Great Barrington, Massachusetts. Figure 4 shows the Stanley’s first transformer. In 1889, the first three phase transformer was developed by the Russia-born engineer Mikhail Dolivo-Dobrovolsky in Germany. The world’s largest transformer (of that time) with the capacity of 220kV, 120MVA was installed in the year 1942 at the Vartan Substation Stockholm. The picture of the same is shown in the Figure 5.
History of Motors
During the evolution of generators and transformers, the motors were also developed parallelly during that period. By 1820, Oersted and Andre Marie Ampere discovered that electric current produces magnetic field. In 1821, Faraday succeeded in demonstrating the findings of Oersted and Ampere. Faraday demonstrated that the current carrying conductor produces the magnetic field. The setup he used for this demonstration is shown in Figure 6. It consists of the vessel filled with mercury and a conducting rod freely rotating on the surface of mercury. The magnet is placed on the surface of the mercury. The electric current is passed through the conducting rod with the help of battery. Faraday found that as soon as the electric current was passed through the conducting rod, the rod rotated on the surface of the mercury. Through this experiment, he illustrated that the current carrying conductor produced magnetic field and it interacted with another magnetic field created by permanent magnet, which was placed on the surface of the mercury. The two magnetic fields interacted with each other leading to the rotation of the conducting rod which was nothing but the motoring effect and it formed the basic working principle of motor.
In 1831, Joseph Henry had improved on Faraday’s experimental motor and developed another motor that made back and forth motion at 75 cycles per minute. The motion was oscillatory in nature and not rotating in nature. William Sturgeon had invented the commutator in the year 1836 – and first rotary electric DC Motor had been developed by him. The commutator made the motion of the motor unidirectional in nature. Ferraris and Tesla invented commutator-less alternating current induction motors independently. In 1885, Ferraris demonstrated a working model of his single phase induction motor. In 1887, Tesla invented two-phase induction motor. At that time, there was a war between Tesla and Edison for the use of DC and AC power. This war is known as “War of Currents” around the year 1880s. In 1890, Mikhail Dolivo Dobrovolsky introduced the first three-phase induction motor. It became the prototype model, which was then used in Europe and the U.S. He also invented the first three-phase generator and transformer and combined them into the first complete AC three-phase system in 1891. This paved the way for the use of AC power (AC generator) leading to a complete AC three-phase system across the globe. In addition to that, it is worthwhile to mention that G. D. Naidu (Gopalaswamy Doraiswamy Naidu), an Indian inventor and engineer who is referred to as the “Edison of India” manufactured first electric motor in India. The Table shows the pictures of scientists and their inventions on electrical machines.
Conclusion
This small article has presented the history of electrical machines in a very comprehensive manner to the best possible extent. From the history, it can be observed that Faraday has made remarkable contributions on the development of electrical machines namely generators, transformers and motors. The basic governing laws, prototype models of various electrical machines were given by Faraday and hence, Faraday is called the father of electrical machines. Even it is not wrong to call Faraday as father of Electrical Engineering. In the same way, it is also observed that the practical three phase transformers, three phase inductor motors and generators were developed by Mikhail Dolivo Dobrovolsky. Fourteen scientists have significantly contributed on the development of electrical machines at their nascent stage. This short report would bring interest among the students on electrical machines – and this foundational knowledge might kindle young minds for contributing towards new innovations in the field of Electrical Machines.
Dr. A. Venkadesan obtained his B.Tech in Electrical and Electronics Engineering and M.Tech in Electrical Drives and Control (with two gold medals in 2009) from Pondicherry Engineering College under Pondicherry University, Puducherry, India. He received Ph.D. in the area of AI Techniques applied to Power Electronics and Drives from the same college in 2014. He is currently working as an Associate Professor and Head of the Department of Electrical and Electronics Engineering, National Institute of Technology Puducherry, Karaikal. He has 22 publications in reputed international journals and 30 publications in national/international conferences/magazines/book chapters. His areas of interest include Electrical Drives & Control, Green Energy Electrical Drives, Artificial Intelligent Techniques and Renewable Energy Systems.
Dr. G. Koperundevi received her B.Tech in Electrical and Electronics Engineering and M.Tech in Electrical Drives and Control from the Pondicherry Engineering College under Pondicherry University, Puducherry, India. She received her Ph.D in the area of High Voltage Engineering in the year 2011. Currently, she is working as an Associate Professor in the Department of Electrical and Electronics Engineering, National Institute of Technology Puducherry, Karaikal. She has 7 publications in reputed international journals and national/international conferences. Her areas of interest include High Voltage Engineering, Power Electronics and Electric Vehicles.
