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A presentation on Railway Traction systems
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Railway Traction Systems09104007 Anish Nangia
09104011 Anubhav Aggarwal
09104020 Gaurav Manchanda
09104040 Payal Niharika09104050 Sanjoli Jain
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Introduction
Classification
Electric Traction
Railway Traction
Third rail system Overhead system
Contents
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Traction is defined as
a physical process in which atangential force is transmitted across aninterface between two bodies throughdry friction or an intervening fluid film
resulting in motion, stoppage or thetransmission of power
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Traction
Non-Electric
Electric
Classification
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Electrification in traction (in India) is used with three
types of locomotives: Using single phase AC commutator motor
Using DC with tapped transformer and rectifier
Using phase converter and induction motor
Application
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Pros:
High torque-to weight ratio
Regenerative braking is possible
Lesser noise
Less maintenance
Cons:
High Capital cost
Pros & Consof Electric Traction
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Permanent Magnet Motors:
High power density and power factor
High Efficiency
High Cost
Switched Reluctance Machine:
Robust Rotor Structure
High Torque Ripple
Poor Power Factor
Induction Machine
Low Cost
Robust Rotor Structure
Low Power Density
Inferior power factor and efficiency
Motors used for Electric Traction
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Railway Traction
Voltage
Current
DC
AC
Contact System
Third Rail
Overhead
Railway Traction
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Supply for traction systems
DC
Simpler, especially for railwaytraction
Easy control
Easier to maintain
Expensive (for long run) Sparking and corrosion
Unsuitable for regenerativebraking
AC
Efficient and cheaper for longdistances
Less or no maintenance
Reliable
Higher level of adhesion
Complicated control
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Existing Traction Systems use DC motors, because of
the following reasons:1. Less expensive
2. More efficient for some H.P.
3. Rail conductor track system is less costly for DC thanfor AC.
Trends in Traction System
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Advantages of AC motor over DCmotors
Commutators-prone to
fail due to vibration andshock
DC motor not suitable forregenerative braking,requires complex andbulky extra components
DC motors tend to injectharmonics in the system
IM doesnt use
commutators Fairly easy to use
regenerative braking
Simpler construction
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Standard voltage levels
Voltage Type600 V DC
750 V DC
1.5 kV DC
3 kV DC
15 kV AC,16.7 Hz
25 kV AC, 50 Hz
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1500 V DC overhead traction system used around
Mumbai Delhi Metro uses 25 kV AC overhead lines with ground
level and elevated routes
Kolkata Metro- 750 DC third rail
Kolkata trams- 550 DC overhead with undergroundconductors
Railway Traction in India
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Third rail system
Third rail or conductorrail placed alongside therail track.
Generally placed outsidebut sometimes placedinside
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Third rail Systen
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Shoe and Shoegear
Shoe is used to collect
the current on train.
Wherever conductor railsare interrupted, shoe is
given a ramp for smoothtransistion
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Shoegears
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Third rail breaks
Gaps usually leads to the
loss of power
Power loss can belessened by using locating
shoes along the train andconnecting them
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Benefits:
Easier to install
Cheaper
Lesser prone to power surges
Disadvantages:
Hazardous
Weather affected
Practical limit on speed
Benefits and Disadvantages
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Overhead System
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In overhead system, there are overhead lines that
supply electricity Trains collect the electricity through pantograph, bow
collecters or trolley poles
The wire must be weather durable, and withstand
wind
Overhead system
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Catenary
Catenary are overhead
wires that form a supportstructure
Helps maintain the lateraland horizontal tension
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Catenary suspension systems
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Pantograph
Used to collect electricity
Easier to isolate
Contact maintained by
spring or air pressure
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Horns provide balance to the contact wires
They also protect the pantograph from obstructionslike tree limbs etc
The horns have no current conducting function
They are directed downwards so that they dont
tangle with overhead lines
Pantograph Horns
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Single Arm Pantograph:Less power, fault prone
Double Arm Pantograph:More power, fault tolerable
Types of Pantograph
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Block Diagram of Modern AC ElectricLocomotive
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Electro-pneumatic contractor type
High voltage; mounted on the roof of the locomotive
All the OHE are connected/disconnected by themeans of this CB
Circuit-Breaker
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Main Transformer of the locomotive
25kV supply fed to this transformer via main bushing
Winding divided into 32 taps (generally)
Taps attached to tap changer
Loco Transformer
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Tap-Changer
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Schematic of a Single-Phase AC
Steps down the25 kV AC
Converts AC tospecified DCVoltage
Smoothens and
Filters the DCoutput
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This is essentially a bank of capacitor and inductor to
give a smooth DC output It also eliminates/reduces the harmonics produced by
drive converters and traction motors
The capacitor bank in this section can also provide a
small amount of reserve power in the transientsituations, if needed by the traction motors
DC Link
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Inverter with three thyristor based components
Three components produces three phase AC
Thyristor components controlled by microprocessor-can produce a wide range of AC frequency andvoltage
Drive Converter
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AC Electric Locomotive with DCmotor
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Track Magnet
To reduce arcing at
neutral section, trackmagnets are used
Track magnets
automatically switch offthe supply when trainreaches neutral section
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Neutral Section
It is a short section ofinsulated and deadoverhead equipment whichseparates the area fed byadjacent substation orfeeding post.
Neutral Section is alsopresent when DC supplychanges over to AC supply,and the links are joined byonly a neutral section
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Benefits and Disadvantages
Benefits
Robust
Less hazardous
Efficient
Disadvantages
Prone to lightening surges
Capital extensive
May require reconstruction
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Thank youAny queries?