Metadyne

For other uses, see Metadyne (disambiguation).

A Metadyne is an electrical machine with three, or more, brushes. It can be used as an amplifier or rotary transformer. It is similar to a third brush dynamo but much more complex, having additional regulator or "variator" windings. it is similar to an amplidyne except that the latter has a compensating winding. 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.

Uses

Metadynes have been used to control the aiming of large guns and for speed control in electric trains, e.g. London Underground O Stock. The equipment in the latter case weighed three tons. They have been superseded by solid state devices. The concept and original patents were issued to the Macfarlane engineering company of Cathcart, Scotland. They were licensed to 'Met Vick' (Metropolitan-Vickers) and there was a cross licence or some form of agreement with GE USA who patented almost to the day the 'Amplidyne' which works the same way (the difference is simply in the amount of compensation that is made for armature reaction). Macfarlane used the concept in two main applications: constant current for electric welders and, in Amplidyne form, for alternator voltage and current control.

History

The history of the metadyne is very complex. The name is believed to have been coined by Pestarini in a paper which he submitted to the Montefiore International Contest at Liège, Belgium in 1928. However, machines similar to the metadyne had been experimented with much earlier, e.g. by Rosenberg in 1904. British patent number 26,607 of 1907 by Felton and Guilleaume also refers to a similar machine. Development work at Metropolitan-Vickers in the 1930s was led by Arnold Tustin.

Sources

• Duffy, M. C. (2000-2001). "The Metadyne in Railway Traction". Transactions of the Newcomen Society 72: 235–264.