The Thury system René Thury

diagram of thury system balancing voltage of supply voltage of load

in 1889, system first put service in italy acquedotto de ferrari-galliera company. earlier company had built water supply genoa gorzente river, , interested whether turbines electrical generation might address long standing problem of reducing excess pressure. first turbine of 140 hp (100 kw) installed @ galvani station, turned 2 thury 6-pole dynamos each produce 1000 1100 volts @ 45 amperes. in order keep same current, speed varies 20 475 rpm, regulated changing flow through water turbine. circuit supplied 15 motors along line stretching genoa, including 60 hp (44 kw) motor @ railway station, , motor transformers @ central electric lighting station in genoa. additional generation plants followed providing lighting motive power number of mills, factories , railway repair shops.

an example of mechanical voltage conversion employed described lighting of sampierdarena train station. thury system powered 60 hp (44 kw) motor drove via belts twelve siemens , 2 technomasio dynamos station s lights. genoa s thury system progressively upgraded transmit 630 kw @ 14 kv dc on circuit distance of 120 km, using later dynamos capable of producing 2.5 megawatts (5000 volts @ 500 amperes) using double commutators reduce voltage on each commutator.

thury systems installed on next few years @ several sites:

1889 first station @ 6 kv supplying genoa gorzente river hydro turbines.
1897 in la chaux-de-fonds (14 kv)
1899 between st-maurice , lausanne (22 kv, 3.7 megawatts)
1906 lyon-moutiers project (final capacity: 20 megawatts, 125 kv, 230 km)
1911 metropolitan electric supply company, london, 100-ampere 5,000-volt generators

the moutiers-lyon system transmitted 20 megawatts of hydroelectric power distance of 124 miles (200 km), including 6 miles (10 km) of underground cable. system used 8 series-connected generators dual commutators total voltage of 150,000 volts between poles, steadily upgraded 4.3 20 mw , ran 1906 until 1936. 1913, fifteen thury systems in use in england, hungary, russia, switzerland, france , italy. thury systems operated 1930s, rotating conversion machinery required high maintenance , had high energy loss.

the main limitations of thury system series distribution meant greater opportunity power failures. placing loads in series means since current must flow through each device next, if circuit broken in of devices, current stops @ other loads. such series distribution possible automatic short circuiting mechanisms in thomson-houston , brush high voltage dc arc light systems, since each load not independent in modern parallel distribution, approach inherently more fragile.

attention turned conversion of dc lower voltages more efficient , less cumbersome mechanically driving smaller generators in sampierdarena railway station example.

in 1920s, economical conversion , hvdc began possible glass bulb mercury arc rectifiers, came late thury system.

this challenge dc systems because induction principle used in step down transformers pioneered lucien gaulard , zbd in 1880s worked ac. not until grid controlled mercury arc valves became available power transmission during period 1920 1940 possible utilize high-voltage direct current large transmission projects, time ac transmission dominant, cheap , reliable.