From the time i had heard of Magnetic Levitation i was very much fascinated by them and wanted to learn more about the working of these trains. This fascination towards something so awesome in technology using just the concept of magnets has led to one of the most revolutionary mode of transport changing the way we commute, hats of to the person who conceived this idea.
We have always thought of aeroplanes as the fastest mode of transportation. As it travels thousands of miles in an hour we do not mind the flight delays and also the risk in flying. There is no other alternative to planes that can travel such a great distance in minimum amount of time. Buses, cars, boats and even conventional trains seem to be too slow in comparison to planes.
Now a new transportation mode has occurred that can clearly compete with planes in both speed and safety. They are called MAGLEV trains. The full form and the basic working principle of MAGLEV is called Magnetic Levitation.
Magnetic Levitation
The principle of magnetic levitation is that a vehicle can be suspended and propelled on a guidance track made with magnets. The vehicle on top of the track may be propelled with the help of a linear induction motor. Although the vehicle does not use steel wheels on a steel rail they are still referred to as trains as by definition they are a long chain of vehicles which travel in the same direction. This is the definition of a MAGLEV train.
As the frictional parts are minimum in this type of technology, the MAGLEV trains are known to have more speed, smoothness and less sound.
Working of MAGLEV Train
The train will be floating about 10mm above the magnetic guiding track. The train will be propelled to move by the guide way itself. Thus, there is no need of any engine inside he train. The detailed working of MAGLEV train is shown in the figure below. The train is propelled by the changing in magnetic fields. As soon as the train starts to move, the magnetic field changes sections by switching method and thus the train is again pulled forward. The whole guide way is run by electromagnets so as to provide the magnetic effect.
Thus the power needed for the whole process is less when compared to a conventional electric train. Amongst the power used, only a little is used for the levitation process. But a higher percentage of power is needed to overcome air friction.
MAGLEV v/s Conventional Train
The main difference between both the trains is that conventional trains need steel wheels and a steel track for their movement and MAGLEV does not need wheels. They travel under the principle of electromagnetic suspension.
Another difference is in the engine used. MAGLEV trains do not need engines like conventional trains. The engine used for conventional trains provide power to pull a chain of compartments along steel tracks. In MAGLEV trains, the power to propel the train is provided by the magnetic fields created by the electric coils kept in the guidance tracks which are added together to provide huge power.
MAGLEV Track
The track along which the train moves is called the guide way. Both the guide way as well as the train’s undercarriage also have magnets which repel each other. Thus the train is said to levitate about 0.39 inches on top of the guide way. After the levitation is complete, enough power has to be produced so as to move the train through the guide way. This power is given to the coils within the guide way, which in turn produces magnetic fields, which pulls and pushes the train through the guide way.
The current that is given to the electric coils of the guide way will be alternating in nature. Thus the polarity of the coils will be changing in period. Thus the change causes a pull force for the train in the front and to add to this force, the magnetic field behind the train adds more forward thrust.
Commercial use of MAGLEV Trains
- The first known commercial use of MAGLEV train was in the year 1984 in Birmingham, England, and the train was named MAGLEV itself. But due to less reliability, the train was stopped by 1994.
- The most famous commercial MAGLEV train is the Shanghai MAGLEV train in Shanghai, China. The train can go in a top speed of 270 miles/hour with an average speed of 160 miles/hour.
- Since these trains move on a cushion of air, there is no friction at all [except air friction]. The trains are also aerodynamically designed which enables them to reach great speeds like 300 miles/hour and so on. At 300 miles/hour you can travel from Rome to Paris in about 2 hours.
EMS and EDS Systems
Some of the greatest developers of the MAGLEV trains are Germany and Japan. Although the basic concepts used for the construction are the same, the prototypes used are different. German trains use electromagnetic suspension (EMS) system so as the bottom of the train is wrapped to a steel guide way. Thus levitation occurs between the electromagnets that are attached underneath the train and the guide way to about 1 centimetre. It also helps in keeping the train in levitation, when it is standing still. Such trains were tested to go on a maximum speed of about 300 miles/hour with passengers on-board.
In Japan, MAGLEV trains use a technology called electro-dynamic suspension (EDS) system, which causes the trains to move due to the repelling force of magnets. The main difference with EMS is that, the electromagnets used will be super cooled and superconducting. Such magnets are prone to conduct current even if there is no power supply. Thus EDS system helps to save more power than EMS system. But the cooling mechanism and thus the initial cost will be expensive.
In EDS systems, the levitation distance is almost 10 centimetres above the guide way. This distance will need the use of rubber tires for the initial lift-off speed of the train [up to 62 miles/hour]. Since the EDS system produces superconducting magnetic field, people having pacemakers will have to be guarded from magnetic fields.
Advantages of MAGLEV
- The main advantage is maintenance. There is no contact between the guide way and the train which lessens the number of moving parts. Thus the components that wear out is little.
- Another advantage is the reduction in noise. As there are no wheels running along there is no wheel noise. However noise due to air disturbance will still be there.
- The next advantage is high speed. As there are no frictional contacts, the train is prone to have more speed.
- Another advantage is that the guide way can be made a lot thicker in uphill places, after stations and so on. This will help in increasing the speed of the train further.
Disadvantages of MAGLEV
The initial cost of MAGLEV trains are highly costly. The guide paths are also supposed to be more costly than conventional steel railways.
Environmental Friendliness of MAGLEV Trains
MAGLEV trains are more environmentally friendly than other types of trains. In terms of energy consumption maglev trains are slightly better off than conventional trains. As there is no wheel friction with the ground, the resistive force gradually increases in the air friction. Thus the energy efficiency difference between a MAGLEV train and a conventional train is of very small margin.
SHRIRAM SPARK 