Technical Seminar
ELECTRICAL TRACTION
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.
Sankarsan Mohapatro
EE 200113364
Technical Seminar
ELECTRICAL TRACTION
Ideal Traction System
(i)
Maximum tractive effort should be exerted at
starting
(ii) Equipment should be capable of overloads for
short periods
(iii) The wear caused on the track should be minimum
(iv) Braking should be possible without excessive wear
on the brush
Sankarsan Mohapatro
EE 200113364
Technical Seminar
ELECTRICAL TRACTION
Advantages & Disadvantages of Electric Traction
Advantages
Cheapness, Acceleration & Braking, Cleanliness,
Maintenance Cost, Starting time, High starting time,
Braking, Saving in high-grade coal, Better coefficient of adhesion
Disadvantages
(i) High initial expenditure
(ii) Failure of supply is a problem
(iii) Electrically operated vehicles have to move only on
electrified track
(iv) For braking & control, additional equipments
required
Sankarsan Mohapatro
EE 200113364
Technical Seminar
ELECTRICAL TRACTION
System Of Track Electrification
(i)
(ii)
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]
Sankarsan Mohapatro
EE 200113364
Technical Seminar
ELECTRICAL TRACTION
Advantages & Disadvantages of 25 kV A.C. System
Over D.C. System
Advantages
1. Light overhead catenary
2. Saving in sub-stations
3. More flexibility
4. Lesser equipment used & easy to maintain
5. Starting efficiency
6. Cheap as far as cost for fixed installation
Disadvantages
1. Single-phase A.C. system imposes Unbalancing effect
2. Produces interference with telecommunication lines
Sankarsan Mohapatro
EE 200113364
Technical Seminar
ELECTRICAL TRACTION
Railway Service Categories
1.
2.
3.
Main line service
City service
Suburban service
Sankarsan Mohapatro
EE 200113364
ELECTRICAL TRACTION
Technical Seminar
Block Diagram Of an A.C. Locomotive
Sankarsan Mohapatro
EE 200113364
Technical Seminar
ELECTRICAL TRACTION
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.
Sankarsan Mohapatro
EE 200113364
Technical Seminar
ELECTRICAL TRACTION
Auxiliary Equipment
1.
2.
3.
4.
5.
6.
7.
Overhead conductors for track electrification
Pantograph
Transformer or Auto-transformer
Rectifier unit
Driving axle & gear arrangements
Train lighting
Multiple control
Sankarsan Mohapatro
EE 200113364
Technical Seminar
ELECTRICAL TRACTION
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
(i)
It should be fast and reliable.
(ii) The braking force must be capable of being controlled
(iii) Kinetic energy of the rotating parts of the motor and its
driven machine must be suitably dissipated & suitable
means must be provided.
Sankarsan Mohapatro
EE 200113364
Technical Seminar
ELECTRICAL TRACTION
Advantages & Disadvantages of Electric Braking
Advantages
(i) It is quite fast
(ii) It is quite cheap as far as maintenance part
(iii) Higher speed can be maintained
(iv) Heat produced during braking is not harmful
(v) It is free from fires and is smoother
Disadvantages
(i) It can stop the motor but it cannot hold it
stationary.
(ii) It cannot be applied to all motors
(iii) Its initial cost is very high.
Sankarsan Mohapatro
EE 200113364
Technical Seminar
ELECTRICAL TRACTION
Types Of Electric Braking
(1) Plugging Braking
(2) Rheostatic Braking
(3) Regenerative Braking
Sankarsan Mohapatro
EE 200113364
Technical Seminar
ELECTRICAL TRACTION
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.
Sankarsan Mohapatro
EE 200113364
Technical Seminar
ELECTRICAL TRACTION
Thank You
Sankarsan Mohapatro
EE 200113364