The Maglev

What is Magnetic Levitation?

Magnetic levitation is the use of magnetic fields to levitate a object.

Using either Ferromagnetism or Diamagnetism, objects can be levitated.

Most important application of Magnetic Levitation is Maglev trains.

Superconductors

Below a certain temperature the resistance offered by certain materials becomes zero.

Linear Induction Motor

It works on the same principle of induction motor but designed to produce linear motion.

Concept of linear induction motor is used to propel the maglev train.

Working…

Maglev trains have to perform the

following functions to operate in highspeeds:-

LevitationPropulsionLateral Guidance

Techniques for Levitation: Electromagnetic

Suspension(Attractive) Electrodynamics Suspension(repulsive)

Electromagnetic Suspension(EMS)

Electromagnetic Suspension uses electromagnets to levitate the train

How ??

In this system electromagnets are placed on top side of the casing extending below pull the train up, causing it to levitate.

The guide way ,which is in the shape of an inverted T, is a ferromagnetic rail.

When a current is passed through it, and the electromagnets gets charged, there is attraction between guide way and train due to which the train levitates.

Electrodynamic Suspension uses Superconductors for levitation, propulsion and lateral guidance

Electrodynamic Suspension

The passing of superconducting magnets in levitation coils on the side of the tract induces a current in the coils and creates a magnetic field. This pushes the train upward so that it can levitate 10 cm above the track.

The train does not levitate until it reaches 50 mph, so it is equipped with retractable wheels.

PRINCIPLE OF MAGNET LEVITATION

Propulsion

The propulsion coils are located on the sidewalls on both sides of the guide way which are energized by a three-phase alternating current from a substation, creating a shifting magnetic field on the guide way.

The on-board superconducting magnets are attracted and pushed by the shifting field, propelling the Maglev vehicle.

Braking is accomplished by sending an alternating current in the reverse direction so that it is slowed by attractive and repulsive forces.

When one side of the train nears the side of the guide way, the super conducting magnet on the train induces a repulsive force from the levitation coils on the side closer to the train and an attractive force from the coils on the farther side.

This keeps the train in the center.

PRINCIPLE OF LATERAL GUIDANCE

An EDS system can provide both levitation and propulsion using an onboard linear motor.

EMS systems can only levitate the train using the magnets onboard, not propel it forward.

Over long distances where the cost of propulsion coils could be prohibitive, a propeller or jet engine could be used.

Advantages …

Maglev uses 30% less energy than a high-speed train traveling at the same speed.

The operating costs of a maglev system are approximately half that of conventional long-distance railroads.

Research has shown that the maglev is about 20 times

safer than airplanes, 250 times safer than conventional railroads, and 700 times safer than automobile travel.

Maglev vehicle carries no fuel to increase fire hazard

The materials used to construct maglev vehicles are non-combustible, poor penetration transmitters of heat, and able to withstand fire.

Disadvantages…

The main disadvantage of the Maglevs are the high initial cost.

Whole new sets of tracks would have to be built for the Maglev to run.

Although the Maglevs are pretty quiet, noise caused by air disturbance equivalent to sonic boom at high speed still occurs

Applications…

NASA plans to use magnetic levitation for launching of space vehicles into low earth orbit.

Boeing is pursuing research in MagLev to provide a Hypersonic Ground Test Facility for the Air Force.

The mining industry will also benefit from MagLev.

There are probably many more undiscovered applications!

Conclusion Even though three maglev train designs have

been developed to commercial readiness, we have yet to see any maglev systems in continuous commercial operation. Obstacles to commercial use of the maglev trains include:-

Expense, especially in guide-way construction Existence of conventional high-speed rail

systems, such as the French TGV Health concerns regarding exposure to

electromagnetic fields Absence of a commercially successful example

to reassure investors Possibility of selecting a guide-way design that

will be incompatible with future systems

References

Magnetic levitation theory

http://en.wikipedia.org/wiki/Magnetic_levitation

Online digital education connection

http://www.odec.ca/projects/2004/leun4m0/public_html/Intro.html

CHSST manual

http://hsst.jp/mechanism_e.htm

Maglev Transportation System in Japan,

http://weber.u.washington.edu/~jbs/itrans/hsst_his.ht 

Superconductivity

 http://en.wikipedia.org/wiki/High-temperature_superconductor

Transrapid

http://en.wikipedia.org/wiki/High-temperature_superconductor

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