André Blondel

Infobox Scientist
name = André Blondel
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caption = André Blondel in 1888
birth_date = August 28, 1863
birth_place = Chaumont, Haute-Marne
death_date = November 15, 1938
death_place = Paris
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nationality = French
ethnicity =
field = physicist
work_institutions =
alma_mater = École polytechnique
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known_for = oscillograph
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influenced =
prizes = Faraday Medal
religion =
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André-Eugène Blondel (August 28, 1863 - November 15, 1938) was a French engineer and physicist. He is the inventor of the electromechanical oscillograph and a system of photometric units of measurement.

Life

Blondel was born in Chaumont, Haute-Marne, France. His father was a magistrate from an old family in the town of Dijon. He was the best student from the town in his year. He went on to attended the École nationale des ponts et chaussées (School of Bridges and Roadways) and graduated first in his class in 1888. He was employed as an engineer by the Lighthouses and Beacons Service until he retired in 1927 as its general first class inspector See IEEE Industry Applications Magazine May-June 2004] . He became a professor of electrotechnology at the School of Bridges and Highways and the School of Mines in Paris See Hebrew University of Jerusalem] .

Very early in his career he suffered immobility due to a paralysis of his legs, which confined him to his room for 27 years, but he never stopped working. See Academie de Poitiers]

In 1893 André Blondel sought to solve the problem of integral synchronization, using the theory proposed by Cornu. He determined the conditions under which the curve traced by a high speed recording instrument would follow as closely as possible the actual variations of the physical phenomenon being studied .

This led him to invent the bifilar and soft iron oscillographs. These instruments won the grand prize at the St. Louis Exposition in 1904. They were more powerful than the classical stroboscope, invented in 1891 then in use. They remained the best way to record high-speed electrical phenomena for more than 40 years when they were replaced by the cathode ray oscilloscope. They paved the way for a greater understanding of the behavior of alternating current .

Blondel built a theory of rectification with asymmetrical electrodes. He demonstrated, that there were three kinds of electric arc : the primitive arc of Duddell, the secondary arc of Poulsen, and a succession of oscillatory discharges .

In 1892, he published a study on the coupling of synchronous generators on a large AC electric grid. This analysis had also been done a little earlier by another electrical engineer, P. Boucherot, using a different approach and the two authors arrived at similar conclusions .

In 1894 he proposed the lumen and other new measurement units for use in photometry, based on the metre and the Violle candle.

In 1899, he published "Empirical Theory of Synchronous Generators" which contained the basic theory ofthe two armature reactions (direct and transverse). It was used extensively to explain the properties of salient-pole ac machines .

He was appointed commander of the Légion d'honneur in 1927 and a life member of the French Academy of Sciences in 1913. He was awarded the Faraday Medal in 1937. He also received the medal of the Franklin Institute, the Montefiore award and Lord Kelvin award.

In 1909, assisted by M. Mähl , he worked on one of the first long distance schemes for the transmission of AC power. The project created a (then ) large 300,000-hp hydroelectric power plant at Genissiat on the River Rhone, and transmitted electrical power to Paris more than 350km away using polyphase AC current at 120kV .

He died in Paris on November 15, 1938.

Notes

References

* [http://ieeexplore.ieee.org/iel5/2943/28690/01286548.pdf André Blondel - French Scientist and Engineer] by Gerard-Andre Capolino in IEEE Industry Applications Magazine, May/June 2004. Accessed June 2008
* [http://chem.ch.huji.ac.il/history/blondel.html André-Eugène Blondel ] Institute of Chemistry at The Hebrew University of Jerusalem. Published on April 17, 2003. Accessed June 2008
* [http://ww2.ac-poitiers.fr/sc_phys/spip.php?article42&debut_page=3 Some portraits - Andre Blondel] Academie de Poitiers, France. Accessed June 2008 (French) [http://66.102.9.104/translate_c?hl=en&sl=fr&tl=en&u=http://ww2.ac-poitiers.fr/sc_phys/spip.php%3Farticle42%26debut_page%3D3 Google translation]