Three-phase AC railway electrification, which promised some advantages over established DC electric rail power and steam traction, started at the turn of the twentieth century. The first standard gauge line, from 1899 to 1933, was from Burgdorf to Thun in Switzerland (40 km or 25 mi). Italy was the major user, from 1901 until 1976, although lines through two tunnels also used the system; the Simplon Tunnel between Switzerland and Italy from 1906 to 1930 (but not connected to the Italian system), and the Cascade Tunnel of the Great Northern Railway in the United States from 1909 to 1939. Single phase AC railways with a single overhead line proved more practical. Since the 1980s, modern electric locomotives use three-phase AC internally, generated from a single overhead line, thanks to advances in semiconductor inverter technology. These inverters are also used in electric cars, from a DC battery, or from DC photovoltaic panels into the three-phase AC grid.
Advantages The system provides regenerative braking with the power fed back to the system, so is particularly suitable for mountain railways (provided the grid or another locomotive on the line can accept the power). The locomotives use three-phase induction motors. Lacking brushes and commutators, they require less maintenance. The early Italian and Swiss systems used a low frequency (16+2⁄3 Hz), and a relatively low voltage (3,000 or 3,600 volts) compared with later AC systems. (However, both regenerative braking and 16+2⁄3 Hz were successfully implemented also for single-phase systems, like for the Swiss Ce 6/8 II and III "Crocodile" type.)
In Germany, the Siemens and AEG Experimental three-phase railcars set new overall speed records, in 1903 at 210.2 kilometres per hour (130.6 mph), faster than any other manned vehicle for about a decade. Due to issues with the three overhead wire concept, German railways continued with single phase AC.
Disadvantages The overhead wiring, generally having two separate overhead lines and the rail for the third phase, was more complicated, and the low frequency used required a separate generation or conversion and distribution system. Train speed was restricted from one to four speeds which obtained by pole-changing, cascade operation or both.
Historical systems The following is a list of the railways that have used this method of electrification in the past:
The Cascade Tunnel of the Great Northern Railway. The Ferrovia della Valtellina in Italy. The Giovi Railway between Genoa and Pontedecimo in Italy. The Italian part of the Mont-Cenis line Turin–Modane. Many other lines in Northern Italy. The Santa Fe - Gergal line in Spain. The Burgdorf–Thun railway in Switzerland. The Simplon Tunnel between Switzerland and Italy.
Current systems The system is mostly used today for rack (mountain) railways, where the overhead wiring is less complicated and restrictions on the speeds available less important. Modern motors and their control systems avoid the fixed speeds of traditional systems, as they are built with solid-state converters. The four current such railways are
The Corcovado Rack Railway in Rio de Janeiro Brazil. The Gornergratbahn in Switzerland. The Jungfraubahn in Switzerland. The Petit train de la Rhune in France, still using the original locomotives of 1912 All use standard frequency (50 Hz, or 60 Hz (Brazil)) rather than low frequency, using between 725 and 3,000 volts. Automated guideway transit in China and Japan can also use three-phase electrification via multiple third rails located on the side of the guideway.
Voltage and frequency This list shows the voltage and frequency used in various systems, historical and current.
Various, Siemens Factory Experiments 1892 200 V / 25 Hz Panama Canal 1915 350 V / 40 Hz Lugano Tramway 1895 460 V / 60 Hz Panama Canal Authority, date unknown 500 V / ?? Hz Ganz Factory Experiment 1896 550 V / 40 Hz Gornergratbahn, at opening, 1898 600 V / 60 Hz Taoyuan International Airport Skytrain, at opening, 2003 600 V / 50 Hz Bukit Panjang LRT line, at opening, 1999 650 V / 50 Hz Zhujiang New Town APM System, at opening, 2010 725 V / 50 Hz Gornergratbahn, current 750 V / 40 Hz Burgdorf–Thun railway, 1899–1933 750 V / 40 Hz Hasle-Rüegsau–Langnau railway, 1919–1932 900 V / 60 Hz Corcovado Rack Railway, 1910 1,125 V / 50 Hz Jungfrau Railway 3,000 V / 15 Hz Ferrovia della Valtellina 1902–1917 3,300 V / 16.7 Hz Galleria del Sempione, SBB 1906–1930 3,000 V / 15.8 Hz Valtellina FS 1917–1930 3,600 V / 16.7 Hz Valtellina FS 1930–1953 3,600 V / 16.7 Hz Genoa-Turin, Turin-Frejus-Modane Gallery (F) and other lines in Piedmont and Liguria from 1910 to 1976 3,600 V / 16.7 Hz Trento-Bolzano-Brennero, Bolzano-Merano FS 1929–1965 3,600 V / 16.7 Hz Genova-La Spezia e Fornovo FS 1926–1948 3,600 V / 16.7 Hz Sondrio-Tirano (Ferrovia Alta Valtellina) 5,200 V / 25 Hz Gergal-SantaFe FC Sur - Spagna 6,600 V / 25 Hz Cascade Range, Great Northern Railway (U.S.), 1909–1927 7,000 V / 50 Hz Experiments, Torino-Bussoleno FS 1927–1928 10,000 V / 45 Hz Roma-Sulmona FS 1929–1944
Converter systems This category does not cover railways with a single-phase (or DC) supply which is converted to three-phase on the locomotive or power car, e.g., most railway equipment from the 1990s and earlier using solid-state converters. The Kando system of the 1930s developed by Kálmán Kandó at the Ganz Works, and used in Hungary and Italy, used rotary phase converters on the locomotive to convert the single-phase supply to three phases, as did the phase-splitting system on the Norfolk and Western Railroad in the United States.
Locomotives
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