Electrification

Report
CE 515 Railroad Engineering
Railway
Electrification
AREMA Chapter 9
Image: Ohio State University
“Transportation exists to conquer space and time -”
Electric Traction Development
• 1835: Thomas
Davenport – developed
electric railway using a
model railroad with a
third rail
• 1879: Werner von
Siemens – first practical
electric railway
• 1890: Siemens' brothers
- London underground
railway (two 50 hp
motors)
• 1898: Arthur Koppel introduced mass
production battery and
electric locomotive in
the US
Image: Getty (under fair use)
Image: Mike’s Rail History prior to 1935
Image: Mike’s Rail History prior to 1935
Image: Scientific America Supplement
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Electric Traction Development
• 1895: first electric
train in the US
• Power was supplied at
550 to 675 VDC
• 1905: Railways started
using and converting
DC to AC power with
up to 25 kV
• Example of power
used in the US:
Image: 1902, viewliner LTD
Image: Eric, 2009
– High speed: 12.5 – 25 kV
– Heavy haul: 25 – 50 kV
– Commuter: 650 – 12 kV
• Most efficient found in
1960s was 25 kV
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Image: City of Montreal
Electric over Diesel-Electric
• Straight-Electric Advantages:
– Higher speeds and low-end torque
– Able to utilize multiple power sources (coal, nuclear,
hydroelectric)
– Minimize local air emissions
– Can employ regenerative braking to add electricity to the grid
– Can improve capacity without adding infrastructure
• Diesel-Electric Advantages:
– Lower initial capital cost
– Does not require elaborate electrical grid system
– Can operate during any power state and in areas where power
cannot be reached easily
– Minimizes electrical safety hazards to the public with no
exposed high-voltage rails or wires.
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• Street Car
• Advance Light Rapid
Transit
Image: RTD
Image: City of Toronto
• Light Rail
Image: MARC
Image: Metro
• Heavy Haul
• Commuter Rail
• Metrorail
Image: Eric
http:[email protected]/3125900050
• Inter-City
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Image: University of
West Virginia
Existing Electrification Systems
Elements of an Electrification System
• Sources of primary power
• Substations to transform the power into a form
suitable for train operations
• Power distribution system
• Current collectors to draw the power
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Sources of Primary Power
• Railways will receive electrical power from
multiple sources
– Coal, nuclear, hydroelectric
• Railroads rarely will generate own electricity
• AC and DC power substations provide one level
of redundancy
– Two transformers will power two different sections so one can
be taken offline for maintenance
• DC substations use a rectifier transformer to
step down and convert AC power
• Distribution system:
– Feeder cables (power distribution to contact system)
– Negative return cables (attached to the rails)
– Contact system
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Power Distribution Systems
Image: FHWA 2005
• Third Rail Power System
– Rigid and mounted parallel to
the track on sleeper ties using
an insulator
– terminated at rail crossings,
turnouts, and diamonds
– Issues experienced include:
• Icing, limited voltage, stray return
currents the leak into the ground
– Catenary wire and contact
wire(s)
– One or two contact wires in
tension
– Breaks allow for
maintenance
– Return wire connected to the
rail complete the circuit
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Image: RTD
• Catenary Power System
Power Collection Systems
• Contact Shoe
Images: southernelectric.org.uk, how stuff works, flicker
– For third rail systems
– Overrunning, under, and side
• Trolley Poles and
Pantographs
– For overhead catenary systems
– Single pole, diamond, z-shaped
– Consist of a wide carbon
rubbing strip
– 6 ft. 6 inches above the rain
with a 4 ft. 4 inch rubbing strip
– High tension contact
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Images: RTD, njrail.com
In tension to prevent
Pantograph oscillation
Signals and Communication
Images: railroad.net
• Trains are detected through
electrical track circuits of
the train control system
• Signaling systems cannot
work if the rails are used as
negative returns
• An impedance bond
connects to the tracks
across the insulated joint
• Allows traction current to
pass through while keeping
the signaling system track
circuit separated
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