1. Introduction
Electric traction means a locomotion in which the driving force is obtained from electric motors.
Electric traction will continue to play a dominant role in the Railway since it is an environmentally clean technology compared to diesel traction and also its running cost is low.
There are many advantages of electric traction over other forms of locomotion.

2. Ideal Traction System
Maximum tractive effort should be exerted at starting
Equipment should be capable of overloads for short periods
The wear caused on the track should be minimum
Braking should be possible without excessive wear on the brush

3. Advantages & Disadvantages of Electric Traction
Cheapness, Acceleration & Braking, Cleanliness, Maintenance Cost, Starting time, High starting time, Braking, Saving in high-grade coal, Better co-efficient of adhesion
Disadvantages
High initial expenditure
Failure of supply is a problem
Electrically operated vehicles have to move only on electrified track
For braking & control, additional equipments required

4. System Of Track Electrification
D.C. Systems
A.C. Systems
(a) Three phase A.C. system
(b) Single phase standard frequency system
(c) Single phase low frequency system
(d) Single phase to three phase system [Kondo system]

5. Advantages & Disadvantages of 25 kV A.C. System Over D.C. System
Light overhead catenary
Saving in sub-stations
More flexibility
Lesser equipment used & easy to maintain
Starting efficiency
Cheap as far as cost for fixed installation
Disadvantages
Single-phase A.C. system imposes Unbalancing effect
Produces interference with telecommunication lines

6. Railway Service Categories
Main line service
City service
Suburban service

7. Block Diagram Of an A.C. Locomotive

8. Review Of Existing Electric Traction In INDIA
Before independence in our country electric trains are working in western region near Bombay & in southern region Madras.
The Tram cars, however were also working in some cities.
All these system operated & still operating on D.C. supply of 1500 V & 600 V for trains & trams respectively.

9. Auxiliary Equipment Overhead conductors for track electrification
Pantograph
Transformer or Auto-transformer
Rectifier unit
Driving axle & gear arrangements
Train lighting
Multiple control

10. Braking Characteristics
If any electric motor is to be stopped, electric supply to it is disconnected.
In this way, the motor shall take long time to stop, as the motor shall continue to rotate due to inertia.
Some braking system must be used so that it stops within the pre-determined short time.
A good braking system must posses the following features
It should be fast and reliable.
The braking force must be capable of being controlled
Kinetic energy of the rotating parts of the motor and its driven machine must be suitably dissipated & suitable means must be provided.

11. Advantages & Disadvantages of Electric Braking
It is quite fast
It is quite cheap as far as maintenance part
Higher speed can be maintained
Heat produced during braking is not harmful
It is free from fires and is smoother
Disadvantages
It can stop the motor but it cannot hold it stationary.
It cannot be applied to all motors
Its initial cost is very high.

12. Types Of Electric Braking
Plugging Braking
Rheostatic Braking
Regenerative Braking

13. Conclusion
India with its large railway network and the growth of large metropolitan centers is building up a large market for railway transport equipment.
Clean technologies due to environmental considerations.
Energy conservation to minimise wastage of power. Faster/reliable railway transportation.
The success of space, defence and atomic energy can be replicated by the Railways also.

14. Thank You