Gramme, Zénobe Théophile

SUBJECT AREA: Electricity, Public utilities

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b. 4 April 1826 Jehay-Bodignée, Belgium

d. 20 January 1901 Bois de Colombes, Paris, France

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Belgian engineer whose improvements to the dynamo produced a machine ready for successful commercial exploitation.

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Gramme trained as a carpenter and showed an early talent for working with machinery. Moving to Paris he found employment in the Alliance factory as a model maker. With a growing interest in electricity he left to become an instrument maker with Heinrich Daniel Rühmkorff. In 1870 he patented the uniformly wound ring-armature dynamo with which his name is associated. Together with Hippolyte Fontaine, in 1871 Gramme opened a factory to manufacture his dynamos. They rapidly became a commercial success for both arc lighting and electrochemical purposes, international publicity being achieved at exhibitions in Vienna, Paris and Philadelphia. It was the realization that a Gramme machine was capable of running as a motor, i.e. the reversibility of function, that illustrated the entire concept of power transmission by electricity. This was first publicly demonstrated in 1873. In 1874 Gramme reduced the size and increased the efficiency of his generators by relying completely on the principle of self-excitation. It was the first practical machine in which were combined the features of continuity of commutation, self-excitation, good lamination of the armature core and a reasonably good magnetic circuit. This dynamo, together with the self-regulating arc lamps then available, made possible the innumerable electric-lighting schemes that followed. These were of the greatest importance in demonstrating that electric lighting was a practical and economic means of illumination. Gramme also designed an alternator to operate Jablochkoff candles. For some years he took an active part in the operations of the Société Gramme and also experimented in his own workshop without collaboration, but made no further contribution to electrical technology.

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Principal Honours and Distinctions

Knight Commander, Order of Leopold of Belgium 1897. Chevalier de la Légion d'honneur. Chevalier, Order of the Iron Crown, Austria.

Bibliography

9 June 1870, British patent no. 1,668 (the ring armature machine).

1871, Comptes rendus 73:175–8 (Gramme's first description of his invention).

Further Reading

W.J.King, 1962, The Development of Electrical Technology in the 19th Century, Washington, DC: Smithsonian Institution, Paper 30, pp. 377–90 (an extensive account of Gramme's machines).

S.P.Thompson, 1901, obituary, Electrician 66: 509–10.

C.C.Gillispie (ed.), 1972, Dictionary of Scientific Biography, Vol. V, New York, p. 496.

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