Have you been to an airport recently, you must have seen that air travel is increasingly being congested. In spite of numerous delays and flight cancellation,airplanes are still the fastest means to travel several miles in a short time. Passenger air travel changed the transportation industry completely in the last century, allowing people move through large distances in hours instead of days or weeks or months.
The option to airplanes - feet, cars, buses, boats and old trains - are seriously too slow for today's fast-paced world. There is a new means of transportation that can completely change transportation of the 21st century the way aeroplanes did in the 20th century. Some countries are using very powerful electromagnets to produce very high-speed trains, known as Maglev trains.
Maglev is shortened form for magnetic levitation meaning that these trains float on top a guideway employing the basic principles of magnetism to replace the archaic steel wheel and track trains. In this write up, we will know how electromagnetic propulsion operates, how the three types of maglev trains work.
Electromagnetic Suspension (EMS)
Have you ever played with magnets before,you must have noticed that opposite poles(north and south) attract and like or similar(north-north or south-south) poles repel each other. This is the basics behind the principle of electromagnetic propulsion. Electromagnets are like other type magnets because they all attract metals, but the magnetism is temporary not permanent. You can easily make a small electromagnet by connecting the ends of a copper wire to the positive and negative terminals of an AA, C or D-cell battery. This generates a magnetic field. If you remove either end of the wire from the battery, the magnetic field ceases to exist.
The magnetic field generated with this wire and battery experiment is the basic principle behind a maglev train rail system. There are three basic components in this system:
1.A gigantic electrical power source.
2.Metal coils lining a guideway or track.
3.Huge guidance magnets fitted beneath the train.
The huge difference between a maglev train and a conventional train is that a maglev train does not have an engine. The engine for a maglev train is rather hidden.Instead of combusting fossil fuels, the magnetic field generated by the electrified coils in the guideway walls and the track combine together to propel the train forward.
The Maglev Track
The magnetized coil fitted along the length of the track, known as a guideway, repels the gigantic magnets beneath the train, letting the train to levitate between 0.39 and 3.93 inches (1 to 10 centimeters) above the guideway. Once the train is levitated,electrical power flows to the coils located in the guideway walls to generate a peculiar system of magnetic fields that pull and push the train along the guideway. The electric current that flows to the coils in the guideway walls is constantly changing to alternate the polarity of the magnetized coils.This alternation in polarity makes the magnetic field in front of the train to drag the vehicle forward, while the magnetic field behind the train adds more forward thrust.
A Maglev train rests on a cushion of air, removing friction. This absence of friction and the trains' aerodynamic makeup allows the train to attain record speed of more than 310 mph(500 kph), nearly twice as fast as Amtrak's fastest passenger train. In comparison, a Boeing-777 commercial aeroplane used for long distance travel can attain a speed of 562 mph (905 kph). Developers say that maglev trains may connect cities up to 1,000 miles (1,609 kilometers) apart. At 310 mph, you can travel from Paris to Rome in about two hours.
Germany and Japan are currently developing maglev train technology, and both are presently conducting tests on prototypes of their trains. (A German firm "Transrapid International" has a train presently in commercial use). Although based on the same idea, the German and Japanese trains have striking differences. In Germany, engineers have developed an electromagnetic suspension(EMS) system, known as Transrapid. In this system, the base of the train curves round a steel guideway. Electromagnets fitted to the train's underside are pushed up towards the guideway, which levitates the train about 1/3 of an inch (1 centimeter) high up above the guideway and makes the train levitated even when stationary. Other magnets are fixed to the trains body as guidance magnets,to keep it stable when moving. Germany has showed that a Transrapid maglev train can attain speed of 300 mph with passengers on board.
Electrodynamic Suspension (EDS)
Japanese engineers and scientists are developing an alternative version of maglev train that uses an electrodynamic suspension(EDS) system,based on the repulsive force of magnets. The main difference between Japanese and German maglev trains is that the Japanese trains uses super-cooled and superconducting electromagnets. This type of electromagnet conducts electricity long after switching off the power supply. In the EMS system, which employs standard electromagnets, the coils only conduct electricity when a power supply is switched on . By cooling the coils at extreme low temperatures, Japan's system conserves energy.However, the cryogenic system employed to cool the coils are highly expensive.
Another difference is that the Japanese trains levitate about 4 inches (10 centimeters) above the guideway. One major drawback in the EDS system is that maglev train must roll on rubber tires till they attain a liftoff speed of 62 mph (100 kph). Japanese engineers said the wheels are an advantage if a power failure caused a shutdown of the system. Germany's Transrapid train is fitted with emergency power supply. Also, passengers with pacemakers need to be protected from the magnetic fields produced by the superconducting electromagnets.
The Inductrack is a recent type of EDS that uses room-temperature magnets to generate magnetic fields instead of using powered electromagnets or cooled superconducting magnets. Inductrack employs a power source to speed up the train till it starts to levitate. If there is a power failure, the train slows down gradually and brakes on its auxillary wheels.
The track is made of an array of electrically-shorted circuits containing insulated wire. In a particular type, these circuits are arranged like rungs in a ladder. As the train advances, a magnetic field repels the magnets, making the train to levitate.
There are two types Inductrack versions: Inductrack I and Inductrack II. Inductrack I is suited for high speed travel, while Inductrack II is suited for slow speed travel. Inductrack trains can levitate higher having higher stability. So far as it is travelling at a few miles per hour, an Inductrack train will levitate close to an inch (2.54 centimeters) above the track. A bigger space above the track means that the train will not need more complex sensing systems to retain stability.
Permanent magnets had not been considered for use before now ,since scientists thought that they will not be able to generate sufficient levitating force. Inductrack designs overcomes this problem by setting the magnets in a Halbach array. The magnets are arranged as such for the intensity of the magnetic field to concentrate above the array but not below it. They were produced using a newly developed material which consists of a neodymium-iron-boron alloy, that produces a stronger magnetic field. The Inductrack II design employs two Halbach arrays for generating a stronger magnetic field at lower travel speeds.
Dr. Richard Post of the Livermore National Laboratory in California brought up this idea to take care of safety and cost concerns. The test prototype draw the attention of NASA and they awarded a contract to Dr. Post and his team to look at the scenerio of using the Inductrack system to put satellites into orbit.
On Aug. 11, 2006, a maglev train passenger compartment on the Transrapid Shanghai airport line had a fire outbreak. There were no reported casualities and accident investigators thought that the fire was caused by an electrical fault.
On Sept. 22, 2006, a Transrapid test train in Emsland, Germany had 29 people on board during a test run when it ran into a repair vehicle that had been unknowingly left on the track.The train was moving at 120 mph (193 kph) at the time. All passengers were killed in the first fatal accident involving a maglev train.
Maglev Technology Currently In Use
Maglev transportation was first thought of more than a century ago, the foremost commercial maglev train made its debut in Shanghai, China, in 2002, using the train developed by German company Transrapid International. The same line made its fore most public commercial run a year later in December of 2003. The Shanghai Transrapid line that runs back and forth between the Longyang Road station in the center of the city and Pudong airport. Moving at speed of 267 mph (430 kph), the 19 mile (30 kilometer) distance takes less than 10 minutes on the maglev train compared to an hour-long taxi ride.
How Maglev Trains Work
4/ 5Oleh Hesty Aristyawati