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

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: High speed: 12.5 – 25 kV Heavy haul: 25 – 50 kV Commuter: 650 – 12 kV Most efficient found in 1960s was 25 kV Image: 1902, viewliner LTD Image: Eric, 2009 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.

Existing Electrification Systems Inter-City Heavy Haul Commuter Rail Metrorail Light Rail Street Car Advance Light Rapid Transit http://www.flickr.com/photos/90001203@N00/3125900050 Image: Eric Image: Metro Image: MARC Image: RTD Image: City of Toronto Image: University of West Virginia

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

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

Power Distribution Systems 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 Power System 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 Image: FHWA 2005 Image: RTD

Power Collection Systems Contact Shoe 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 In tension to prevent Pantograph oscillation Images: southernelectric.org.uk, how stuff works, flicker Images: RTD, njrail.com

Signals and Communication 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 Images: railroad.net