Gramme

Zénobe Theophile Gramme was Belgian industrialist, inventor, electrical engineer, whose improvements to the direct-current dynamo produced the first machine ready for successful commercial exploitation. He showed that the direct-current dynamo (a generator) can be reversed to a direct-current motor.

The son of a tax clerk, Zénobe Theopile Gramme was born on April 4, 1826 in the small town Jehay-Bodegnee, Belgium. He never finished school and he went to work at an early age as a joiner in Hannut. He followed his family when they moved to Liege and he remained there until 1855. It was while traveling in France that he settled in Paris as a banister maker. He married Hortense Nysten, a dressmaker from Liege, and the two made their home in the Paris suburb of Neuilly-sur-Seine.

Trained as a carpenter, Zénobe Gramme moved into instrument making as a model maker for Floris Nollet's Alliance. Gramme went to work for a model maker in a firm that specialized in the manufacture of arc lamp generators. This marked the beginning of his interest in electricity as he became interested in building an improved apparatus for producing alternating current. He began his experiments in the 1860's, and in 1867, he took out his first patent for a device dedicated to improve magneto-electrical machines. In 1869 he devised his first clean direct-current dynamo (a generator using electromagnets) in which he drew upon the work of Pacinotti.

Model of the electromotor of Gramme

Gramme's generator featured a ring armature wound with many individual coils of wire and on July 17, 1871 Gramme's invention was presented by the physicist, Jules Jamin to the Academie des Sciences. To avoid eddy currents the core of his machine was built using iron wire insulated with bitumen. The most important part in this design, however, was the new type of commutator. In contrast to Pacinotti, who had not thoroughly grasped the essentials of commutation, Gramme almost completely solved the problem, which is widely considered as one of the most decisive technical inventions of the nineteenth century.

Scheme of the electromotor of Gramme

**Gramme's magneto-electric machines**
	Unlike the earlier magneto-electric machines, the Gramme machine used a series of thirty armature coils, placed inside a revolving ring of soft iron. The coils are connected in series, and the junction between each pair is connected to a commutator strip on which two brushes run. The permanent magnets magnetize the soft iron ring, producing a magnetic field which rotates around through the coils in order as the armature turns. This induces an EMF in two of the coils on opposite sides of the armature, which is picked off by the brushes. With thirty coils, the resulting voltage waveform is practically constant, thus producing a near DC signal. This type of machine needs only electromagnets to produce the magnetic field to become a true generator.

***Z. Gramme's Generator, 1875, Paris, Technikmuseum Berlin***

In 1873 Gramme demonstrated that his direct-current dynamo can also work in reverse as a motor, allowing the commercial generation of electric power. The dynamos of Gramme were used in lighthouses, in electroplating, for manufactory's illumination and were drived by steam engines.

Gramme's Generator

Gramme dynamo (two different variants), 1870

In order to have his device manufactured, he founded in partnership with the French engineer Hippolyte Fontaine and in 1871 they opened a factory: the Societe des Machines Magneto-Electriques Gramme, where they produced among other things the Gramme ring, Grammae armature, and the Gramme dynamo. In 1873, at the Vienna Exposition, one of his motors served as a generator for another located three-quarters of a mile away. "For the first time there was available a small powerful source of power that could run for days with little or no attention. And suddenly it became clear that ELECTRICITY could now do heavy work, transporting power through wires from place to place. It was a revelation and immediately hundreds of minds turned to the possible uses of the idea." Henry Adams (American) wrote about the DYNAMO as "a moral force" comparable to the European cathedrals in the essay "The Dynamo and the Virgin."

Zénobe T. Gramme

The significance of Gramme's machine was that it stimulated developments in electricity which soon followed. In spite of the fact that Gramme himself was semi-literate and had no advanced knowledge of mathematics, his discoveries of the principles of the dynamo and the electrical engine were of the utmost importance to modern technology. He developed his dynamo into a system particularly for powering an improved arc light invented in Paris that required alternating current and high voltage. The system was quite widely used in Europe, though it consumed carbons at a very high rate. In 1852 Gramme was a winner of the 50,000-franc Volta Prize established by Louis-Napoleon.

Zénobe T. Gramme

**Burial of Zénobe Theopile Gramme in *Le Pere Lachaise* cemetery, Paris**
		Zénobe Theopile Gramme mainly lived in Paris until he died in Paris on January 20, 1901. He was burried in the Parisian Père Lachaise cemetery, where his tomb can still be visited.

Belgium postal stamp commemorating 100 years from Gramme's death and his electrical dynamo. Date of issue: 19 March 2001.

This text has been compiled from the biographies of Gramme available in the Internet:
( 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 )