Tuesday 17 November 2015

ELECTRIC TRACTION - PART - 11 - TYPES OF TRACTION SYSTEMS

ADVANTAGES OF ELECTRIC TRACTION SYSTEM
1. It is a clean traction system.
2. Well suited for underground railways.
3. No need for separate generator is required for lights and
    fans, power can be drawn directly from the lines.
4. Speed control is possible.
5. It has the advantages of rapid acceleration and retardation.
6. Less maintenance is required.
7. It can be started instantly.
8. It can take large overloads.
9. Pollution free.
10. Very economical system.

DISADVANTAGES OF ELECTRIC TRACTION
1. Its initial cost is very high.
2. Failure of supply paralyses the whole system.
3. It produces electro-magnetic interference with the
    neighboring telecommunication lines.

Electric traction is suitable for suburban and urban raiway where frequent starting and stopping and high schedule speeds are required.
It is capable of handling greater volume of traffic.
The system can be subdivide into and run in sections during the periods of light traffic.
Frequent service of trains can be maintained leading to increased traffic during these periods.

SYSTEMS OF TRACTION
1. DIRECT STEAM ENGINE SYSTEM
Steam engine drive is the most widely used traction system in almost all the UNDERDEVELOPED countries.

ADVANTAGES
1. Simplicity in design.
2. No telecommunication interferences
3. Low capital cost, because track electrification is not
    required.
4. Seep control is simple

DISADVANTAGES
1. Poor thermal efficiency.
2. Noisy in operation.
3. Due to unbalanced reciprocating part there is considerable wear on the track.
4. Corrosion of steel structure due to smoke emitted by the engine.
5. It pollutes the atmosphere.
6. Low efficiency.
7. It takes own time for starting.
8. No suitable for underground system.
9. High maintenance cost.
10. Speed of locomotive is very low.

2. DIRECT INTERNAL COMBUSTION SYSTEM  
It is suitable for road and light railway work, it is unsatisfactory work on railways. [buses, cars and trucks]

ADVANTAGES
1. It has low initial cost.
2. Very compact and self-contained unit.
3. Speed control with gear and arrangement is quite simple.
4. It has a efficiency of 25%.
5. Its braking arrangements are simple.

DISADVANTAGES
1. The life of the equipment (vehicle) is short.
2. Overload capacity is low.
3. Manintenace and running costs are fairly high.
4. It produces air pollution.
5. It requires gear arrangement for speed control.

3. DIESEL ELECTRIC DRIVE
This system is used in Indian Railways.
In this system gear system is eliminated. The diesel engine is coupled to a dc generator which supplies d.c traction motors.

ADVANTAGES
1. For conversion from steam engine to diesel traction, no modification of existing track is required.
2. No overhead transmission system is required hence capital is low.
3. The efficiency of the system is comparatively higher, about 25%.
4. The haulage capacity is larger as compared with steam locomotive.
5. Simple starting method.
Speed control with gear and arrangement is quite simple.
6. It has a efficiency of 25%.
7. Its braking arrangements are simple.

DISADVANTAGES
1. The diesel engine has a shorter life span.
2. Overload capacity is very much limited.
3. Maintenance and maintenance costs are fairly high.
4. Cooling systems are needed for diesel engine as well as for the motor generator set.

4. BATTERY – ELECTRIC SYSTEM
In this system vehicle carries batteries which run d.c. motors used for driving the vehicle. This system is not suitable for railways.
It is mainly used in mines, ports and large factories.
The batteries are connected in parallel for starting and running half of the maximum speed.
The batteries are connected in series for running at maximum speed.

ADVANTAGES
1. Low maintenance cost.
2. convenient to use.
3. Pollution free.

DISADVANTAGES

1. The major disadvantage is limited capacities of the batteries and the problem of charging them frequently.

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