Ludwig Roebel

This article deals with the engineer Ludwig Roebel. For the major general see Ludwig Philipp von Röbel .

Ludwig Roebel (born May 6, 1878 in Kusel , † April 7, 1934 in Königsfeld in the Black Forest ) was a German engineer and inventor .

Thanks to his idea of ​​the Roebel staff , it became possible to build large electric motors and generators and thereby produce electricity in almost any quantity at low cost. This paved the way for the breakthrough in electrical energy in households and businesses.

Roebel attended grammar school in Landau in the Palatinate and then studied at the TH Munich . He then worked from 1905 to 1909 at the Siemens-Schuckert works as an electrical engineer. He then moved to Brown, Boveri & Cie. (BBC; predecessor of ABB and the power plant division of Alstom ) to the Käfertal plant in Mannheim , at that time the BBC's largest plant in Germany, where he succeeded in inventing the winding bar that was later named after him, which revolutionized the construction of generators and large electric motors. This technology was used in 1914 at the Elverlingsen power plant (Elektromark, today MarkE), when the world's largest turbo group with an output of 20,000 kilowatts was put into operation.

Roebel patent from 1912

On July 11, 1933, Roebel received from the Technical University of the Free City of Danzig under the rectorate of Prof. Dr. Heuser “In recognition of his outstanding services to the development of electrical engineering in various areas, in particular through the invention of the artificial rod named after him to avoid eddy current losses”, he was awarded the honorary doctorate degree (Dr.-Ing. E. h.).

Up until Ludwig Roebel's invention, the stator windings of the alternators were provided with bars made of solid copper. Despite the enlargement of the copper cross-section in the generators, the current (and thus the output) could not be increased to the same extent. Due to the magnetic stray fields, eddy currents occurred and the current was displaced in the rod, so that the current did not flow through the entire copper cross-section. So if you wanted to increase output, you had to use disproportionately more material, and yet these machines often got too warm. Therefore it was hardly possible to build generators with more than 10 to 20 MW.

Thanks to Roebel's idea of ​​building the rod from several mutually insulated sub-conductors that are interwoven, the effects of the magnetic stray fields on the rod are balanced out and the entire copper cross-section is used almost evenly. It was only with this invention that larger generators could be built. In 1912 his invention was patented. (Excerpt from the patent specification: “... a conductor for electrical machines, which consists of two or more groups of flat partial conductors, ... which are interwoven and twisted with the help of bends ... so that ... in all Partial conductors connected in parallel induce the same electromotive forces and avoid eddy currents ”. Every company that wanted to build large alternators and three-phase generators afterwards had to pay license fees to the BBC. That is why the term “Roebel staff”, which is internationally known in technology, is still reluctantly used by Roebel’s first employer, where they speak of “interwoven subordinate staff” or choose its English translation. To this day, Roebel's invention is the basis of all windings in large three-phase generators or motors; however, it is hardly known in everyday life. Today, in generator construction, outputs of over 1,600 MW per unit are achieved.

The former BBC / ABB generator plant in Mannheim-Käfertal later belonged to the Alstom Group and was closed in spring 2008.

literature

• Hans-Erhard Lessing: Mannheim pioneers . Wellhöfer-Verlag, Mannheim 2007

Web links

• biography
• Information about the BBC Käfertal plant