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26  Silicon Chip February 1996  27 M AGLEV TRAINS USE roughly 30% less energy than conventional trains travelling at the same speed and they compare even more favourably with cars and air­planes. In terms of energy demand per passenger, cars consume 3.5 times as much energy, while airplanes consume four times as much as a maglev travelling at 400km/h. Dispensing with wheels also means that Transrapid generates no audible rolling noise, even during acceleration and braking. Its aerodynamically related noise becomes perceptible only at speeds over 200km/h, making it ideal for densely populated areas. And because it wraps around its guideway, rather than perching on a track, it cannot derail. Furthermore, since the guideways are usually elevated, nothing can cross a maglev’s path. All of this should add up to an unprecedented level of safety. In fact, 28  Silicon Chip studies indicate that maglev trains should be 250 times safer than conventional rail transportation, 20 times safer than air travel and 700 times safer than road transportation. Nor does maglev technology pose problems for passengers with pacemakers, as the magnetic field inside the cabin is the same order of magnitude as the Earth’s natural field. Made of non-flammable materials developed for aviation, Trans­­ rapid also offers the very best in fire prevention. Magnetic levitation represents the most environmentally responsible form of mass transportation available. In addition to minimal energy demand and low noise, maglev technology allows for grades as steep as 10% and a track radius of 2.2km for a speed of 300km/h. This means that the maglev guide­ way can be flexibly adapted to the landscape. Whether elevated or at ground level, it requires less area and has less environmental impact than other ground transportation systems. Magnetic attraction Transrapid uses the forces of magnetic attraction and repulsion for suspension and guidance, while propulsion and braking are managed by a synchronous long-stator motor. The levitation system is based on the attractive and repulsive forces of the electromagnets that are in the vehicle and on the ferromagnetic reaction rails in the guideway. Suspension magnets draw the vehicle along the guideway and guidance magnets keep it laterally on “track”. The maglev propulsion system is based on a synchronous long-stator linear “motor”. The motor consists of stator cores with a three-phase winding installed under the guideway together with vehicle-mounted electromagnets. An electric travelling-wave field generated by current in the windings of the stator cores pulls the vehicle along by attracting its suspension magnets which also act as the exciter section of the linear motor. In other words, unlike the drive principle behind traditional propulsion systems, the maglev’s primary propulsion system is not on the vehicle itself but in the guideway. Compared to conventional locomotives which must have enough on-board propulsion capacity to overcome the steepest grades, maglev trains rely on individual track sections to supply them with the appropriate amount of power. Thus, in sections requiring greater thrust, the output of the guideway motor is boosted as the vehicle passes. Furthermore, by activating only those sections of track being used at Right, a section of the highly automated Transrapid modular control system, developed by Siemens. February 1996  29 Energy supply Switch (closed) Guidance rail Guidance magnet Switch (open) Switch (closed) Motor winding Stator pack Energy supply Support magnet Fig. 1: Transrapid’s levitation system is based on the attraction of electromagnets in the vehicle and the ferromagnetic (steel) guidance rails. any given moment, energy losses are minimised. Financing the project Officially authorised by Germany’s lower house of parliament, the Bunde­ stag, on March 2nd, 1994, the DM 8.9 billion ($A8.4b) Transrapid project will be financed by a combination of public and private interests. A government holding company will be responsible for managing DM 5.6 billion in right-of-way and site preparation investments, while a consortium that includes banks, insurance companies, German Rail (DB) and Lufthansa will provide the remaining financing. Based on technology developed in cooperation with the German Federal Ministry for Research and Technology, the trains are being built by Thyssen, AEG and Siemens. Siemens has developed a highly automated operations control system for the management of maglev trains. Fig. 2: the linear motor, essentially a stretched out stator in the guideway, is divided into sections. A given section is energised only when the train is crossing it. When a maglev train leaves a station, a control centre takes responsibility for all the associated operational tasks and peripheral systems. A fundamental subsystem is the “wayside-installed decentralised vehicle control”. Responsible for set­ point optimisation, as well as route and vehicle protection, this system is in constant contact with the propulsion unit, vehicle and guideway, as well as systems within the operations centre. As the train travels along the guide­ way, decentralised control and operation units exchange information with the main control centre in what is essentially a local area network. Siemens’ decentralised operations control equipment has been extensively tested and meets the demanding requirements of multiple train operation. In addition, under the leadership of Maglev Systems Testing and Planning Ltd, Transrapid has been tested since the mid-80s under near Transrapid 105 TGV-A 100 IC 95 Suburban train 90 85 TRANSRAPID 07 80 Freight train 75 70 A competitor for air travel Transrapid is far more than a stylish new train. Because of its remarkable speed, it offers an unbeatable alternative to the automobile and the airplane. Operating at ten minute intervals, as plans for the Berlin-Hamburg route call for, Transrapid can be expected to significantly reduce traffic density and associated air pollution between major cities. In fact, planners expect the train to attract some 14.5 million passengers each year. Because of its minimal space requirements it can, in many cases, be added to existing railway right-ofways while freeing up conventional SC track for freight traffic. Track-mounted drive Maximum Noise Level at 25 m Distance Ref.: Noise Measurements T†V Rheinland and Others (1989) 110 routine service conditions at a facility in Emsland in northern Germany. In November, 1991, German Rail pronounced the maglev system ready for revenue service and by June 1995 Transrapid had clocked more than 200,000km on its test track. 0 50 100 150 200 250 300 350 400 450 500 km/h Fig. 3: travelling below 200km/h, magnetic levitation trains generate no audible rolling noise, even during acceleration and braking. 30  Silicon Chip Power supply Railroad Gradient (10%) Vehicle-mounted drive Gradient (max. 4%) Fig. 4: the guideway motor system provides increased power in those sections with steeper gradients. Because the guideway linear motor rather than on-board engines does the work, maglev trains can be lighter and negotiate much steeper grades than conventional trains. Acknowledgement: this article has been reproduced by ar­rangement from Siemens Review, Volume 62, May 1995.