20-11-2012, 12:12 PM
Maglev Trains
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What is a magnet?
It is simply an object which produces a magnetic field
North and South are the designations made to describe the two opposite poles
North is attracted to South and repelled by North
South is attracted to North and repelled by South
There are three main types:
- Permanent - Soft Magnets
- Electromagnets
Permanent Magnets
Electrons fill atomic orbitals in pairs
If an orbital is full, then one electron spins upward and the other spins downward (Pauli Exclusion Principle), so their magnetic fields cancel out
If an orbital is not full, then the movement of the electron creates a tiny magnetic field
Atoms with several unpaired orbitals have an orbital magnetic moment
Soft Magnets
These types of magnets do not have a magnetic field of their own
However, when put in the presence of another object’s magnetic field, they are attracted (paramagnetic)
Once the external magnetic field is removed, they return to their nonmagnetic state
Electromagnets
The magnetic field is caused by the flow of an electric current
The simplest example is a coiled piece of wire
Using the right hand rule, it is possible to determine the direction
An advantage over permanent magnets is that the magnetic field strength can be changed by changing the current
How It Works
Support System
The electromagnets on the underside of the train pull it up to the ferromagnetic stators on the track and levitate the train.
The magnets on the side keep the train from moving from side to side.
A computer changes the amount of current to keep the train 1 cm from the track.
Levitation System’s Power Supply
Batteries on the train power the system, and therefore it still functions without propulsion.
The batteries can levitate the train for 30 minutes without any additional energy.
Linear generators in the magnets on board the train use the motion of the train to recharge the batteries.
Levitation system uses less power than the trains air conditioning.
Propulsion System
The system consists of aluminum three-phase cable windings in the stator packs that are on the guide way
When a current is supplied to the windings, it creates a traveling alternating current that propels the train forward by pushing and pulling.
Application Information
Safety
The trains are virtually impossible to derail because the train is wrapped around the track.
Collisions between trains are unlikely because computers are controlling the trains movements.
Maintenance
There is very little maintenance because there is no contact between the parts.
Environment
It uses less energy than existing transportation systems. For every seat on a 300 km trip with 3 stops, the gasoline used per 100 miles varies with the speed. At 200 km/h it is 1 liter, at 300 km/h it is 1.5 liters and at 400 km/h it is 2 liters. This is 1/3 the energy used by cars and 1/5 the energy used by jets per mile.
The tracks have less impact on the environment because the elevated models (50ft in the air) allows all animals to pass, low models ( 5-10 ft) allow small animals to pass, they use less land than conventional trains, and they can follow the landscape better than regular trains since it can climb 10% gradients (while other trains can only climb 4 gradients) and can handle tighter turns.
Summary
Maglev trains use magnets to levitate and propel the trains forward.
Since there is no friction these trains can reach high speeds.
It is a safe and efficient way to travel.
Governments have mixed feelings about the technology. Some countries, like China, have embraced it .