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COMPARISON BETWEEN FEASIBIITY OF HIGH SPEED RAIL & ELECTROMAGNETIC RAIL IN BANGLADESH(PART-4)

ELECTROMAGNETIC RAIL TECHNOLOGY
 


The Transrapid maglev system has no wheels, axles, transmissions, and overhead wires. It does not roll, it hovers. Non-contact, electromagnetic support, guidance and propulsion systems replace the wheels and rails of the railroad. A highly reliable, fully redundant electronic control ensures that the vehicles hover at an average distance of about 10mm (3/8 inch) from its guideway. The distance between the top of the guideway and the underside of the vehicle during levitation is 150 mm (6 inch), enabling the maglev vehicle to hover objects or a layer of snow. The design of the Transrapid support, guidance and propulsion systems is modular, failure tolerant and equipped with automatic diagnostic systems. This ensures that the failure of individual components does not result in a disturbance of operation.
Support and Guidance System
   
 Figure- 05
The non-contact support and guidance system of the Transrapid maglev system functions according to the principle of electromagnetic levitation. It uses the attracted forces between the individual, electronically controlled electromagnets in the vehicle and the ferromagnetic reaction rails, which are installed on the side of the guideway. The support magnets pull the vehicles up to the guideway from below, the guidance magnets keep it laterally on track. The support and guidance magnet are arranged on both sides along the entire length of the vehicle, propulsion system.
 Figure-06
The synchronous longstator linear motor of the Transrapid maglev system is used both for propulsion and braking. The function of this non-contact propulsion and braking system can be derived from the functional principle of a rotating electric motor whose stator is cut open and stretched along both sides of the guideway. Instead of a rotary magnetic field, the motor generates an electromagnetic traveling field. The support magnets in the vehicle function as the rotor (excitation portion) of the electric motor.
  Figure- 07
In contrast to the conventional railroad, the primary propulsion component of the Transrapid maglev system – the stator packs with three-phase motor winding – are not installed in the vehicle but in the guideway.


By supplying alternating current to the three-phase motor winding, an electromagnetic traveling field is generated which moves the vehicle, pulled along by its support magnets, which act as the excitation component. The speed can be continuously regulated standstill to full operating speed by varying the frequency of the alternating current. If the direction of the traveling field is reserved, the motor becomes a generator, which breaks the vehicle without any contact. The braking energy can be fed back into the public network. 

The longstator linear motor in the guideway is divided into individual motor sections, which are only supplied with power as the vehicle passes.

The location and the installed power of the substations depend on the requirements on the propulsion system. In sections where high thrust is required, e.g. gradients acceleration, and braking sections, the power of the substations is higher then on level sections, which are traveled at constant speed.
And because the primary component of the propulsion system is installed in the guideway, Transrapid vehicles need not carry the entire motor power for the peak requirements, as is the case with other types of vehicles.
The support and guidance system is supplied with energy without contact via the linear generators integrated into the support magnets. No overhead wires are required for the Transrapid in the event of a power failure, energy is supplied from on- board batteries, which are charged by the linear generators during travel.
  Figure- 08
Shape of the guideway:



 
  Figure-09
Switches

The Transrapid maglev system changes tracks using steel bendable switches. They consist of continuous steel box beams with lengths between 78 m and 148 m (256 ft-486 ft), which are elastically bent by means of electromagnetic setting drives and securely locked in their end positions. This function is electronically controlled and safeguarded.
Bendable switches can be designed as two-way or three-way switches, either at-grade or elevated.
In the straight position, the vehicle can cross the switch without speed restrictions in the turnout position, the speed is limited to 200 km/hr (125 mph)(high speed switch) or 100 km/hr (62 mph)(low speed switch).

 
Figure- 10
In parking and maintenance facilities, track can also be changed using a transfer table. These operate by laterally moving a straight length of guideway (with the vehicle sitting stationary on top) to access multiple tracks.
Transrapid- Vehicles for passengers and High-Value Cargo
The Transrapid vehicles are flexibly configured to fit the requirements of the most diverse applications. The vehicle sections are built using lightweight, modular structures and can be combined into trains with two to ten sections depending on the application and traffic volume. In addition to passengers, the Transrapid can also carry high-value cargo in specially designed cargo sections. These can be used for dedicated high-speed cargo trains or added passenger trains for mixed service.
Technical Data

 Length
end section
 27.o m
middle section
 24.8 m
Width    

 3.7 m
Height 

 4.2 m
Maximum operation speed                                                               

500 km/h (310 mph)
Empty weight, passenger vehicle            
per section                                 
approx.  53 t

Empty weight, cargo vehicle                   
 per section                                   
 approx.  48 t
Useful payload, cargo vehicle               
 per section                                   
 approx.  15 t
Seats, passenger vehicle                       
 end section        
 max.  92
  middle section                                                                     
 max.  126
The best System –Innovation for More Safety

Despite the high speeds of up to 500 km/h (310mph), you are safer on board the Transrapid than in any other means of transport. The vehicle virtually cannot derail because it warps around its guideway. And since grade crossings are not allowed, nothing can get in its way.
Collisions between Transrapid vehicles are also ruled out due to the technical layout of the system and section-wise switching of the "guideway motor". The vehicle and the traveling field if the guideway motor moves synchronously, i.e. with the same speed and in the same direction. Additionally, the sections of the longstator linear motor in which the vehicle is moving is only switched on as the vehicle passes.
With regard to fire protection, the Transrapid meets the highest requirements of the relevant standard. There are no fuels or combustible materials on board. Only PVC-free materials that are highly inflammable, poor conductors of heat, burn-through-proof and heatproof are used in the vehicles. As an additional safety precaution, fireproof doors can separate the vehicle sections.
Other important elements of the safety concept are:



  • Automatic train protection



  • Passive protection equipment to prevent damage to the guideway structure and violation of the vehicle's clearance envelope



  • Automatic inspection of the guideway



  • Protection of the passengers during boarding and exit in the station by means of platform doors and gap bridges


  •  Even if the power from the public grid fails while the vehicle is running, only the propulsion system (motor) is lost. The vehicle levitation system and all on-board equipment are supplied from on board batteries, so the vehicle continues to levitated and move forward with its existing "momentum". If the next station is too far away, entthe vehicle will be automatically braked to a stock at the next available auxiliary stopping area. These areas are set up for this purpose along the route and convenient access is provided for support services, should they be required. Under these circumstances, the vehicle is braked using eddy current brakes located in each section, also supplied from the on-board batteries. The eddy-current brakes slow the vehicle down to 10 km/h(6mph), upon which the vehicle than sets down on its skids and stops. 

    Even in the rare case of a significant technical failure in the Transrapid system, the vehicle will always be brought to a stop automatically at an auxiliary stopping area. If a fire is reported, the vehicle also automatically stops at the next auxiliary stopping, area as a precaution. If necessary, the vehicle may be quickly and conveniently evacuated there.


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