History of the development of electrical machines and transformers

The possibility of converting electrical energy to mechanical was first established by M. Faraday , who in 1821 created the first model of an electric motor in which an electric current flowing along a copper wire caused its movement around a vertically placed permanent magnet. However, further work to create an electric motor for more than a decade did not bring satisfactory results. Only in 1834 the Russian academician BS Yakobi created a design that served as a prototype of a modern electric motor.

The possibility of creating an electric generator arose only after the discovery by M. Faraday in 1831 of the law of electromagnetic induction . Using this discovery, the Pixie brothers in 1832 created the design of the first electric generator with rotating permanent magnets and with a commutator for rectifying the current.

The first time the development of electric motors and generators went independently of each other.

In 1833 Lenz formulated the principle of reversibility of electric machines , and in 1838 this principle was practically realized.

A further stage in the development of generators was the replacement of permanent magnets by electromagnets.

The initial period of development of electric machines is mainly connected with direct current. This is explained by the fact that the consumers of electrical energy were installations operating exclusively on direct current (arc lamps, electrotype plants, etc.). The use of electric lighting in large cities required an increase in the power of electric generators and their further improvement.

In 1867, W. Siemens applied the principle of self-excitation for generators of sequential excitation . In the same year , Maxwell first gave a mathematical theory of an electric machine with self-excitation, laying the foundations of the theory of electric machines.

In 1870 Z. Gramm built a car with a ring anchor , and in 1873 F. Gefner-Altenek and V. Siemens built a car with a "drum" anchor .

The development of electric railways significantly increased the demand for electric motors and generators, which contributed to their further improvement.

In the 80s of the 19th century, there was a need to transmit electricity over a distance . In 1882, experiments were conducted on the transmission of electric power at a constant current at an increased voltage. However, the high voltage in the DC generators worsened the operation of the collector, which often led to accidents. All this increased the interest of electrical engineers of the time to alternating current.

Much credit for the development of alternating current belongs to the Russian scientist PN Yablochkov , who widely used alternating current to supply the electric candles he invented. In 1876 PN Yablochkov used transformers with an unclosed core to feed these candles, thus putting the practical use of transformers to the fore .

Transformers with a closed core, similar to modern transformers, appeared later, in 1884.

The beginning of the practical application of alternating current for the purpose of the electric drive should be considered in 1889, when the outstanding Russian engineer M.O. Dolivo-Dobrovolsky proposed for practical use a three-phase alternating current system and built a three-phase asynchronous motor and a three-phase transformer .

The first transmission line of three-phase alternating current with a length of 175 km at a voltage of 15 thousand volts with the use of three-phase transformers was built by Dolivo-Dobrovolsky in 1891. The results of tests of this line confirmed the possibility of using a three-phase current system to transfer significant amounts of electricity at a relatively high efficiency.

By the beginning of the 20th century, all the main types of electric machines had been created and the foundations of their theory had been developed. Since this time, the electrification of industry and transport has been proceeding at a rapid pace.

In this regard, the capacity of power plants is increasing, turbogenerators are being created - machines directly connected to a steam turbine. The power of generators and transformers is increasing. If in 1900 the generator power did not exceed 5 thousand kv, by 1920, turbine generators with the capacity of 60 thousand kvas were built. The use of hydrogen cooling made it possible to build turbine generators with a capacity of more than 500 thousand square meters.

Source of the information: Katsman MM Electric machines and transformers. - M .: 1971, p. 9-11.