Direct current line Lyon – Moûtiers
The Lyon – Moûtiers direct current line was the largest system implemented by René Thury using the direct current transmission method. It was in operation from 1906 to 1936 and supplied the electric tram in Lyon with energy from a hydroelectric power station on the Isère near Moûtiers in the Savoie department . The operator was the Société grenobloise de force et lumière (SGFL) .
The voltage in the transmission line was changed depending on the energy demand , and there were also various expansion stages. At the beginning, an output of 4320 kW was achieved with an output voltage of 57.65 kV and in the final stage 14,700 kW was transmitted with 100,000 V at a current of 150 A. The overhead line was 180 km long, followed by a 4 km long underground cable in the city of Lyon. It is remarkable that at that time it could go into operation without the aid of modern power electronic components or parts.
Power plant in Moûtiers
In La Pomblière ( 45 ° 29 ′ 54.9 ″ N , 6 ° 33 ′ 48.6 ″ E ) on the soil of the commune of Saint-Marcel near Moûtiers in the Savoie department, a hydropower plant was built in 1898, using a factory built on the same site for Production of ferrosilicon and the subsequent metal extraction with energy, and which is still in operation today in a similar form. For this purpose, an upstream barrage near the Étroit du Siaix gorge directs the water of the Isère over a 3285 m long underground channel to a pressure pipe with a height difference of 65 m.
The Société Grenobloise de Force et Lumière added a further turbine house in 1905, in which the water from the pressure pipe was distributed to four generating units. Each unit consisted of a Francis turbine that operated four generators connected in series via a horizontal shaft . The turbines were manufactured by the Geneva company Piccard, Pictet et Cie and ran at 300 revolutions per minute. There were two safety clutches on each shaft, which were triggered in the event of overloads, such as those that would occur in the event of a short circuit in the transmission line. Such couplings were fitted from the outset after a line short circuit in the Saint-Maurice VS power station, which was completed in 1899, tore apart the generator shafts. Each coupling was followed by two generators, which were combined in pairs to form an assembly. In the initial expansion stage, each six-pole generator generated 270 kW of power at a voltage of 3600 V and 75 A of current, so that with four groups of four generators connected in series, a maximum voltage of 57,600 V resulted. Since this series connection resulted in very high potentials at the masses, all generator stands were extensively isolated and stood on asphalt concrete floor slabs. The system also had other protective devices, including an emergency power supply from accumulators, bridging switches for each generator and protection against voltage reversal and a battery of surge arresters per generation unit .
Transmission line
The overhead line made of two 64 mm² copper wires ran from La Pomblière through the Isère valley and the valley furrow of Chambéry to a substation in Vaulx-en-Velin , an eastern suburb of Lyon. Up to Sablonnières , the line was installed on wooden pylons, to the west of which steel structures were used to accommodate further lines through which alternating voltage from other power plants of the Société Grenobloise de Force et Lumière came to Lyon.
For legal reasons, an underground line was laid for the rest of the route over built-up areas. This underground cable ran over 4 km from Vaulx-en-Velin to a depot for the Lyon electric trams ( Tramways de Lyon ). The underground cable, which was also carried out twice, was an inner copper strand with a cross-section of 75 mm², surrounded by an 18 mm thick insulator. The latter consisted essentially of tar-soaked fibers. It was considered the first underground cable that was designed for such a high voltage with an insulation value of over 1000 MΩ per kilometer. The underground cable, which was designed for 75 A, was later operated with up to 150 A.
Each of the two overhead line wires had a total resistance of around 90 Ω, plus another 2 Ω from the underground cable. The resulting voltage drop was around 7000 V, which corresponds to a power loss of around 525 kW. The line had an efficiency of 88%, based on the power fed in. Thanks to the extensive protective devices against interference effects, reliable operation was noted from the start, even during thunderstorms in the area of the high-voltage line.
Vaulx-en-Velin substation
On the southern edge of Vaulx-en-Velin, the Société Lyonnaise des Forces Motrices du Rhône (SLFMR) , a competitor of the SGFL, completed the Centrale hydroélectrique de Cusset in 1899 , the largest run-of-river power plant of its time in France. Directly adjacent the substation for high-voltage line of the SgfI (originated at their premises 1906 45 ° 45 '50.7 " N , 4 ° 55' 11.5" O ). Its tasks were to protect the underground cable against environmental influences on the overhead line and other disruptive effects as well as the possibility of feeding alternating current from other SGFL power plants into the tram network if necessary instead of the energy from Moûtiers.
The environmental influences on the overhead line resulted from atmospheric potential differences and indirect lightning strikes in its wider area as well as from electrostatic input (rain, snowfall, dust). Surge arresters and voltage limiters and regulators were installed in Vaulx-en-Velin to ensure a smooth transition between the overhead line and the underground cable. Low-frequency overvoltages were avoided by means of electrical resistors in powder design, while capacitors filtered out high-frequency interference.
In addition, three dynamo groups were installed in the substation, which could be operated in both power directions , to convert direct current into three-phase alternating current and vice versa. Each group had a maximum output of around 500 kW and consisted of two series machines and a synchronous motor on a common shaft that ran at 428 revolutions per minute. In normal operation, the synchronous motor was driven as a generator and part of the power from the direct current line was fed into the alternating current network. In the event of a breakdown in the transmission from Moûtiers, the direction of power was reversed, and SGFL power plants less distant, whose energy was transmitted with alternating current, supplied the tram depot in Lyon with direct current.
Depot in rue d'Alsace
The underground cable connection from Vaulx-en-Velin ended at No. 21, rue d'Alsace ( 45 ° 46 ′ 6.5 ″ N , 4 ° 52 ′ 13.2 ″ E ), a depot of the Tramways de Lyon on the eastern edge of the Urban area on the ground of the municipality of Villeurbanne . The site still serves as a depot for the SYTRAL buses . In the first expansion stage, there were five transformer machines of 500 kW each, which, similar to the one in Vaulx, drove a direct current generator via two series motors and a shaft, which supplied the 600 V for the tram network. The masses of the two machines were separated by means of an insulating coupling sleeve on the shaft. An arrangement of accumulators in the basement could bridge downtimes of up to half an hour.
See also
literature
- MA Rey: Transport d'énergie Moûtiers-Lyon . In: La Houille Blanche . No. 10 , 1908, pp. 229–235 , doi : 10.1051 / lhb / 1908068 (French, online , parallel publication in monthly newspaper 12/1908 of the École Centrale Lyonnaise ).
- The History of Electric Wires and Cables by Robert Monro Black
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