ELECTRIC TRACTION SYSTEM

Presented by:

M.ibrar younas

ContentsElectric traction.

History of electric traction.

Advantages and Disadvantages

Motors used in electric traction.

Advantages of AC system over DC

HISTORY OF ELECTRIC TRACTIONThe years 1881 saw the birth of the first

electric railway run by German Engineer Werner Van Siemens.

Electric traction was introduced on indian railways in years 1925 on 1.5 KV DC

In the years of 1957,indian railway decide to adopt 25KV,50HZ AC traction based on French(SNCF) technology.

WHAT IS ELECTRIC TRACTION

Electric traction is meant for locomotion in which the driving force is obtained from electric motors.

It involves to utilization of electric power for traction system.

ADVANTAGESo High starting torque

o Lower running cost of locomotive & multiple units

o Less noise pollution

o Breaking system is very efficient & simple

DISADVANTAGES.Problem of supply failure

High capital cost

Electrically operated vehicles have to move on guided track only

Motors Used In Electric Traction

Three motors used in electric traction.

D.C series motors.

Single phase A.C series motors.

Three phase induction motors.

D.C SERIES MOTOR.D.C series motor develops high torque at low

speed and low torque at high speed , exact requirement of the traction units.

D.C series motor torque is independent of the line voltages.

D.C series motor unaffected by the variations in the line voltages/

CIRCUIT DIAGRAM & CHARACTIRISTIC CURVE

SINGLE PHASE A.C SERIES MOTOR

CIRCUIT DIAGRAM

CHARACTERISTIC CURVE

3-PHASE INDUCTION MOTORHaving constant speed

Constant torque speed characteristics

Low maintenance cost

High efficiency

Circuit Diagram

Characteristic curve

Advantage of AC motor over DCDc motor use commotators which are prone

to failure because of vibration and shock

It is hard to use dc motor for regenerative breaking

It use extra switch gear therefore system is bulkier

Ac motor have simple construction