First Edition, 2012 ISBN 978-81-323-4395-0 © All rights reserved. Published by: White Word Publications 4735/22 Prakashdeep Bldg, Ansari Road, Darya Ganj, Delhi - 110002 Email:
[email protected] Table of Contents Chapter 1 - Railway Electrification System Chapter 2 - Traction Power Network Chapter 3 - Railway Electric Traction Chapter 4 - Electric Locomotive Chapter 5 - Pantograph (Rail) Chapter 6 - Electric Multiple Unit Chapter 7 - Trolley Pole Chapter 8 - Third Rail Chapter 9 - Overhead Lines Chapter 10 - Ground-Level Power Supply Chapter 1 Railway Electrification System Electric locomotives under the wires in Sweden Overhead wire and catenary in Bridgeport, Connecticut, United States A railway electrification system supplies electrical energy to railway locomotives and multiple units so that they can operate without having an on-board prime mover. There are several different electrification systems in use throughout the world. Railway electrification has many advantages but requires significant capital expenditure for installation. Characteristics of electric traction The main advantage of electric traction is a higher power-to-weight ratio than forms of traction such as diesel or steam that generate power on board. Electricity enables faster acceleration and higher tractive effort on steep gradients. On locomotives equipped with regenerative brakes, descending gradients require very little use of air brakes as the locomotive's traction motors become generators sending current back into the supply system and/or on-board resistors, which convert the excess energy to heat. Other advantages include the lack of exhaust fumes at point of use, less noise and lower maintenance requirements of the traction units. Given sufficient traffic density, electric trains produce fewer carbon emissions than diesel trains, especially in countries where electricity comes primarily from non-fossil sources.