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A metadyne is a direct current electrical machine with two pairs of brushes. It can be used as an amplifier or rotary transformer. It is similar to a third brush dynamo but has additional regulator or "variator" windings. It is also similar to an amplidyne except that the latter has a compensating winding which fully counteracts the effect of the flux produced by the load current. The technical description is "a cross-field direct current machine designed to utilize armature reaction". A metadyne can convert a constant-voltage input into a constant-current, variable-voltage output. ==History== The word ''metadyne'' is derived from the Greek words for conversion of power.〔 While the name is believed to have been coined by Joseph Maximus Pestarini in a paper which he submitted to the Montefiore International Contest at Liège, Belgium in 1928, the type of machine which it described had been known since the 1880s. The first known British patent for a direct-current, cross-field generator was obtained by A. I. Gravier of Paris in 1882, and two further patents were obtained by E. Rosenberg in 1904 and 1907. Rosenberg later became the chief electrical engineer for Metropolitan-Vickers, and his machine produced a cross field by applying a short-circuit to an additional set of brushes. M. Osnos looked at the practical arrangements for several such machines in 1907, and in the same year, Felton and Guilleaume obtained a British patent, number 26,607, which described auxiliary windings, armature windings and multiple commutators, although all in fairly general terms. He also indicated that they could be used to transform a constant voltage into a constant current.〔 Other patents were obtained prior to 1910 by Mather & Platt, Brown Boverei and Bruce Peebles. Pestarini worked on developing the theory of such machines between 1922 and 1930, although he concentrated on their static characteristics, rather than their dynamic characteristics.〔 He contributed three papers on the subject to ''Revue Générale de l'Electricité'' in 1930,〔 which included some practical applications. The main one was the use of the constant-current output for the control of traction motors on electric vehicles and the operation of cranes, areas in which he had some practical experience, following trials in conjunction with the Alsthom Company in France. In 1930, he made a trip to Britain, and the Metropolitan-Vickers company took his ideas and developed a working system.〔 Unlike Rosenberg's solution, Pestarini, who later became a Professor at the Institute Electrotechnico Nazionale Galileo Ferraris in Turin, connected the additional brushes to an external supply to produce a transformer metadyne.〔 The machine worked as a voltage-to-current amplifier because the flux generated by the current to the load opposed the flux in the control circuit.〔 Development work at Metropolitan-Vickers in the 1930s was led by Arnold Tustin, and the company held the British patents for the Metadyne. Pestarini also visited the United States in 1930, although there is no record of the system being used there. The General Electric engineers, led by Ernst Alexanderson, were interested, but modified the design by the addition of a compensating winding, which counteracted the effect of the flux produced by the load current. This turned the machine from a voltage-to-current amplifier into a voltage-to-voltage amplifier, and they called the new variant an Amplidyne. The development costs were largely funded by US naval contracts for the development of vertical stabilisers, which were used to improve the aiming and firing of guns on ships.〔 During the same period, the Macfarlane Engineering Company, who were based in Glasgow, developed a variant of the cross field machine quite independently, which they named the ''Magnicon''. Pestarini filed a patent on the metadyne machine in France on 14 January 1932, and submitted it to the United States Patent Office at the end of the year, on 23 December. The US patent was granted on 30 January 1934. He submitted a second US patent for an improved machine in November 1946, which was granted on 10 June 1952. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Metadyne」の詳細全文を読む スポンサード リンク
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