Jedlik and the phenomenon of self-arousal

Independently of Faraday, the Hungarian Ányos Jedlik began experimenting in 1827 with electromagnetic rotating devices which he called electromagnetic autorotors. In the prototype of the single-pole electric starter (completed between 1852 and 1854) both the stationary and rotating parts were electromagnetic. It was also the discovery of the self-excitation principle of the dynamo,[1]​ which replaced permanent magnet designs. He may also have formulated the dynamo concept "Dynamo (electric generator)") in 1861 (before Siemens and Wheatstone did) but did not patent it because he thought he was not the first to realize it.[2]​.

DC generators

A coil of wire rotating in a magnetic field produces a current that changes direction with each 180° rotation, an alternating current (AC). However, many early uses of electricity required direct current (DC). In the first practical electric generators, called dynamos "Dynamo (electric generator)"), AC was converted to DC with a commutator "Commutator (electric motor)"), a set of rotating switch contacts on the armature shaft. The commutator reversed the connection of the armature winding to the circuit every 180° of shaft rotation, creating a pulsating direct current. One of the first dynamos was built by Hippolyte Pixii in 1832.

The dynamo "Dinamo (electric generator)") was the first electrical generator capable of delivering energy for industry. The Woolrich electrical generator of 1844, now in Thinktank, Birmingham Science Museum, was the first electrical generator used in an industrial process.[3]​ It was used by the firm of Elkingtons for commercial electroplating.[4]​[5][6]​.

The modern dynamo, suitable for use in industrial applications, was invented independently by Charles Wheatstone, Werner von Siemens and Samuel Alfred Varley. Varley obtained a patent on 24 December 1866, while Siemens and Wheatstone announced their discoveries on 17 January 1867, with the latter delivering a paper on their discovery to the Royal Society.

The "dynamo-electric machine" used self-powered electromagnetic field coils instead of permanent magnets to create the stator field.[7] Wheatstone's design was similar to Siemens', except that in the Siemens design the stator electromagnets were in series with the rotor, but in Wheatstone's design they were in parallel.[8] The use of electromagnets instead of permanent magnets It greatly increased the power output of the dynamo and allowed the generation of high powers for the first time. This invention led directly to the first major industrial uses of electricity. For example, in the 1870s, Siemens used electromagnetic dynamos to power electric arc furnaces for the production of metals and other materials.

The dynamo machine that was developed consisted of a stationary structure, which provided the magnetic field, and a set of rotating windings that rotated within that field. In larger machines, the constant magnetic field is provided by one or more electromagnets, which are usually called field coils.

Large power generating dynamos are now rarely seen due to the almost universal use of alternating current for power distribution. Before the adoption of AC, very large direct current dynamos were the only means of power generation and distribution. AC has come to dominate due to AC's ability to easily transform to and from very high voltages to allow low transmission losses over long distances.

Synchronous generators (alternating current generators)

Thanks to a series of discoveries, the dynamo was followed by many later inventions, especially the AC alternator, which was capable of generating alternating current. It is commonly known as synchronous generator (SG). Synchronous machines are connected directly to the grid and must be correctly synchronized during startup.[9]​ In addition, they are excited with a special control to improve the stability of the power system.[10]​.

Alternating current generation systems were known in simple forms from Michael Faraday's original discovery of magnetic induction of electric current. Faraday himself built an early alternator. His machine was a "rotating rectangle", whose operation was heteropolar: each active conductor passed successively through regions where the magnetic field was in opposite directions.[11]​.

Large two-phase alternating current generators were built by a British electrician, J.E.H. Gordon, in 1882. The first public demonstration of an "alternator system" was performed by William Stanley, Jr., an employee of Westinghouse Electric "Westinghouse Electric (1886)") in 1886.[12]​.

Sebastian Ziani de Ferranti founded the company Ferranti, Thompson and Ince in 1882 to market his Ferranti-Thompson alternator, invented with the help of renowned physicist Lord Kelvin. His first alternators produced frequencies between 100 and 300 Hz. Ferranti went on to design the Deptford power station for the London Electric Supply Corporation in 1887 using an alternating current system. Once completed in 1891, it was the first truly modern power station, supplying high voltage AC power which was then "stepped down" for consumer use on each street. This basic system is still in use today throughout the world.

After 1891, polyphase alternators were introduced to supply currents from multiple different phases.[14] Later alternators were designed to vary alternating current frequencies between sixteen and approximately one hundred hertz, for use with arc lighting, incandescent lighting, and electric motors.[15]

Self-excitement

As the requirements for large-scale power generation increased, a new limitation emerged: the magnetic fields available from permanent magnets. Diverting a small amount of the power generated by the generator into an electromagnetic field coil allowed the generator to produce substantially more power. This concept was called self-arousal.

The field coils were connected in series or parallel with the armature winding. When the generator began to spin, the small amount of remanent magnetism present in the iron core provided a magnetic field to start it, generating a small current in the armature. This flows through the field coils, creating a larger magnetic field that generates a larger armature current. This "start-up" process continues until the magnetic field in the core is deactivated due to saturation "Saturation (magnetism)") and the generator reaches a stable power output.

Very large power plant generators often used a separate smaller generator to drive the field coils of the larger ones. In the event of a widespread power outage, stations may be required to perform a black start to excite the fields of their larger generators to restore customer power service.[16]​.

Jedlik and the phenomenon of self-arousal

Independently of Faraday, the Hungarian Ányos Jedlik began experimenting in 1827 with electromagnetic rotating devices which he called electromagnetic autorotors. In the prototype of the single-pole electric starter (completed between 1852 and 1854) both the stationary and rotating parts were electromagnetic. It was also the discovery of the self-excitation principle of the dynamo,[1]​ which replaced permanent magnet designs. He may also have formulated the dynamo concept "Dynamo (electric generator)") in 1861 (before Siemens and Wheatstone did) but did not patent it because he thought he was not the first to realize it.[2]​.

DC generators

A coil of wire rotating in a magnetic field produces a current that changes direction with each 180° rotation, an alternating current (AC). However, many early uses of electricity required direct current (DC). In the first practical electric generators, called dynamos "Dynamo (electric generator)"), AC was converted to DC with a commutator "Commutator (electric motor)"), a set of rotating switch contacts on the armature shaft. The commutator reversed the connection of the armature winding to the circuit every 180° of shaft rotation, creating a pulsating direct current. One of the first dynamos was built by Hippolyte Pixii in 1832.

The dynamo "Dinamo (electric generator)") was the first electrical generator capable of delivering energy for industry. The Woolrich electrical generator of 1844, now in Thinktank, Birmingham Science Museum, was the first electrical generator used in an industrial process.[3]​ It was used by the firm of Elkingtons for commercial electroplating.[4]​[5][6]​.

The modern dynamo, suitable for use in industrial applications, was invented independently by Charles Wheatstone, Werner von Siemens and Samuel Alfred Varley. Varley obtained a patent on 24 December 1866, while Siemens and Wheatstone announced their discoveries on 17 January 1867, with the latter delivering a paper on their discovery to the Royal Society.

The "dynamo-electric machine" used self-powered electromagnetic field coils instead of permanent magnets to create the stator field.[7] Wheatstone's design was similar to Siemens', except that in the Siemens design the stator electromagnets were in series with the rotor, but in Wheatstone's design they were in parallel.[8] The use of electromagnets instead of permanent magnets It greatly increased the power output of the dynamo and allowed the generation of high powers for the first time. This invention led directly to the first major industrial uses of electricity. For example, in the 1870s, Siemens used electromagnetic dynamos to power electric arc furnaces for the production of metals and other materials.

The dynamo machine that was developed consisted of a stationary structure, which provided the magnetic field, and a set of rotating windings that rotated within that field. In larger machines, the constant magnetic field is provided by one or more electromagnets, which are usually called field coils.

Large power generating dynamos are now rarely seen due to the almost universal use of alternating current for power distribution. Before the adoption of AC, very large direct current dynamos were the only means of power generation and distribution. AC has come to dominate due to AC's ability to easily transform to and from very high voltages to allow low transmission losses over long distances.

Synchronous generators (alternating current generators)

Thanks to a series of discoveries, the dynamo was followed by many later inventions, especially the AC alternator, which was capable of generating alternating current. It is commonly known as synchronous generator (SG). Synchronous machines are connected directly to the grid and must be correctly synchronized during startup.[9]​ In addition, they are excited with a special control to improve the stability of the power system.[10]​.

Alternating current generation systems were known in simple forms from Michael Faraday's original discovery of magnetic induction of electric current. Faraday himself built an early alternator. His machine was a "rotating rectangle", whose operation was heteropolar: each active conductor passed successively through regions where the magnetic field was in opposite directions.[11]​.

Large two-phase alternating current generators were built by a British electrician, J.E.H. Gordon, in 1882. The first public demonstration of an "alternator system" was performed by William Stanley, Jr., an employee of Westinghouse Electric "Westinghouse Electric (1886)") in 1886.[12]​.

Sebastian Ziani de Ferranti founded the company Ferranti, Thompson and Ince in 1882 to market his Ferranti-Thompson alternator, invented with the help of renowned physicist Lord Kelvin. His first alternators produced frequencies between 100 and 300 Hz. Ferranti went on to design the Deptford power station for the London Electric Supply Corporation in 1887 using an alternating current system. Once completed in 1891, it was the first truly modern power station, supplying high voltage AC power which was then "stepped down" for consumer use on each street. This basic system is still in use today throughout the world.

After 1891, polyphase alternators were introduced to supply currents from multiple different phases.[14] Later alternators were designed to vary alternating current frequencies between sixteen and approximately one hundred hertz, for use with arc lighting, incandescent lighting, and electric motors.[15]

Self-excitement

As the requirements for large-scale power generation increased, a new limitation emerged: the magnetic fields available from permanent magnets. Diverting a small amount of the power generated by the generator into an electromagnetic field coil allowed the generator to produce substantially more power. This concept was called self-arousal.

The field coils were connected in series or parallel with the armature winding. When the generator began to spin, the small amount of remanent magnetism present in the iron core provided a magnetic field to start it, generating a small current in the armature. This flows through the field coils, creating a larger magnetic field that generates a larger armature current. This "start-up" process continues until the magnetic field in the core is deactivated due to saturation "Saturation (magnetism)") and the generator reaches a stable power output.

Very large power plant generators often used a separate smaller generator to drive the field coils of the larger ones. In the event of a widespread power outage, stations may be required to perform a black start to excite the fields of their larger generators to restore customer power service.[16]​.