JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD

Course Objectives:

• To understand various systems of track electrification, power supply system and mechanics of electric train.
• To identify a suitable drive for electric traction.

Course Outcomes

Upon the completion of the course the student will be able to

• Understand Traction systems and its mechanics
• Identify the power supply equipment for traction systems
• Analyze various types of motors used in traction and differentiate AC and DC traction drives

UNIT - I

Traction Systems : Electric drives - Advantages & disadvantages - System of track electrification - d.c., 1-Phase low frequency, 3-Phase low frequency and composite systems, Problems of 1-phase traction system - Current unbalance, Voltage unbalance, Production of harmonics, Induction effects, Booster transformer - Rail connected booster transformer. Comparison between ac. and d.c. systems.

UNIT - II

Traction mechanics: Types of services, Speed - time curves - Construction of quadrilateral and trapezoidal speed time curves, Average & schedule speeds. Tractive effort - Speed characteristic, Power of traction motor, specific energy consumption - Factors affecting specific energy consumption, Coefficient of adhesion, slip - Factors affecting slip, magnetically suspended trains.

UNIT - III

Power supply arrangements : High voltage supply, Constituents of supply system - Substations, Feeding post, Feeding & sectioning arrangements, Remote control center, Design considerations of substations, Over head equipment - principle of design of OHE, Polygonal OHE - Different types of constructions, Basic sag & tension calculations, Dropper design, Current collection gear for OHE.

UN IT – IV Traction motors : Desirable characteristics, D.C. series motors, A.C. series motors, 3-Phase induction motors, linear induction motors, D.C. motor series & parallel control - Shunt bridge transition – Drum controller, Contact type bridge transition control, Energy saving, Types of braking in a.c. and d.c. drives, Conditions for regenerative braking, Stability of motors under regenerative braking.

UNIT - V

Semi conductor converter controlled drives: Advantages of A.C. Traction - Control of d.c. motors - single and two stage converters, Control of ac. motors - CSl fed squirrel cage induction motor, PWM VSl induction motor drive, D.C. traction — Chopper controlled d.c. motors, composite braking, Diesel electric traction — D.C. generator fed d.c. series motor, Alternator fed d.c. series motor, Alternator fed squirrel cage induction motor, Locomotive and axle codes.

TEXT BOOKS:

• 1. Partab.H - Modern Electric Traction, Dhanpat Rai & Sons – 1998.
• 2. Dubey. G.K. - Fundamentals of Electrical Drives, Narosa Publishing House - 2001.
• 3. C. L. Wadhwa — Generation, Distribution and Utilization of Electrical Energy, New Age International - 2006.
• 4. J.B. Gupta - Utilization of Electrical Power and Electric Traction, S. K. Kataria & Sons th publications, 9 edition 2004.