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electric drives in traction system

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electric drives in traction system Powered By Docstoc
					  BY

  HANISH CHOWDARY.V


 VIGNAN’S INSTITUTE OF INFORMATION
AND TECHNOLOGY
                   VISAKHAPATNAM
INTRODUCTION

 Electric traction makes things easier and safer.
They bring down the distance and time and
break the barriers of time and space. Electric
traction is very economical, easy and safe. They
can largely opt for vehicles, elevators etc
CONTENTS:
1)   Characteristics
2)   Classification
3)   Electric traction drives
4)   Third Rail
5)   Electronic
CHARACTERISTICS:

 The  main advantage of electric trains is
  the superior acceleration, due to the
  excess of power-to-weight ratio that can
  be obtained by modern electric trains.
 Other advantages include the lack of
  exhaust fumes at point of use, less noise
  and lower maintenance requirements of
  the traction units.
Classification:
VOLTAGE :- The common voltages are simple
 multiples of each other.
           1200 V DC    =   2 * 600 V DC
            1500 V DC   =   2 * 750 V DC


CURRENT :- This can be DC or AC. For AC
 systems the frequency is also given.

Contact System :- This refers to the means by
 which traction current is collected by the traction
 unit.
Electric traction drives :-
The DC traction motor : how it drives the motor
NOSE SUSPENDED TRACTION MOTOR :-
The motor case was
provided with a “nose”
which rested on a bracket
fixed to the transom of the
bogie. It was called a
“nose suspended motor.

 Its main disadvantage
is that part of the weight
rests on the axle and is
therefore unsprung. This
leads to greater wear on
bogie and track.
Quill Drive :-
Linear Motor :-




The efficiency of the linear motor is about 60% of
the conventional motor but it has the advantage
of less moving parts and it does not have the
reliance on adhesion of the conventional motor.
Most electrification systems use overhead wires,
but third rail is an option up to about 1200 V.
The top speed of trains on third-rail systems is
limited to 100 mph (160 km/h)
Electronic Power :-



DC gets up to 3000 volts, while AC uses 15,000 - 50,000 volts.

DC motors have been the preferred type for railways because
their characteristics were just right for the job. They were easy
to control too. For this reason, even trains powered from AC
supplies were usually equipped with DC motors
AC Locomotives with DC drives :
DC CHOPPERS :-
i. It is a cheapest method
ii. Maintenance and repair cost of
   electric traction is about 50% of that
   of steam traction system.
iii. It has very high starting torque. High
   starting torque makes acceleration
   rate very high.
i. Higher initial expenditure is involved
    in electric traction.
ii. Failure of supply is a problem to be
    faced in electric traction.
iii.The electrically operated vehicles have
    to move only on electrified track.
         CONCLUSION :

Using these electric drives we can
get better performance and by
applying these electronic control
methods we can easily control our
electric traction motors.
ANY QUERIES
THANK YOU

				
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posted:3/2/2012
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