This document discusses traction motors, which are electric motors that provide rotational torque, usually for converting into linear motion. Traction motors are used in electric rail vehicles. The document outlines key mechanical characteristics of traction motors such as robustness and small size. It also discusses important electrical characteristics like high starting torque and regenerative braking capability. Finally, it examines different types of traction motors including DC series motors and discusses factors driving increased global demand for traction motors.

1.  Traction motor refers to an electric motor providing the primary
rotational torque of a machine, usually for conversion into linear
motion (traction).
 Traction motors are used in electrically powered rail vehicles such as
electric multiple units and electric locomotives.
INTRODUCTION

2. Mechanical Characteristics of Traction Motor
 Robustness & ability to withstand continuous vibrations.
 The weight of the traction motor should be minimum in order
to increase the pay load capacity of the vehicle.
 The traction motor must be small in overall dimentions.
 The traction motor must be totally enclosed type, to provide
protection against dirt, dust, water, mud, etc.

3. Electrical Characteristics of Traction Motor
 High Starting Torque.
 Simple Speed Control
 Self-Relieving Property
 Possibility of Dynamic or Regenerative Braking
 Capability of Withstanding Voltage Fluctuations
 Capability of Withstanding Temporary Interruption of Supply
 Overload Capacity
 Parallel Running

4. 1) Three Phase Induction Motors
2) DC Series Traction Motor
3) Single phase A.C Series Motors
Different Types of Traction Motors

5. Three Phase Induction Motors
Provides constant speed operation, developing low starting torque drawing high starting
current and complicated control networks makes it unsuitable for electric traction work.
Automatic regeneration is the main advantage in electric traction with this motor.

6. DC Series Traction Motor
Develops high torque at low speeds and low torque at high speed, exact
requirement of the traction units.
 Torque is independent of the line voltage and thus unaffected by the
variations in the line voltage.

7. Single phase A.C Series Motor
Starting torque is lower than dc series motor due to poor power factor at
starting.
This motor has surpassed the d.c series motor in terms of size, weight cost for
the same rating.
Maximum operating voltage is limited to 400 Volts.

8. Braking of Traction Motor
Electrical and mechanical, both types of braking are used in
electric traction. Electrical braking in traction motors are as
follows:
 Plugging
 Rheostatic or Dynamic Braking
 Regenerative Braking

9. 1. Plugging
 This is the simplest type of braking. In this method of
braking the torque of the motor is reversed, which brings
the motor and its driven machine to standstill.
 It is done by reversing phase sequence of the motor.

10. 2. Rheostatic or Dynamic Braking
In this method of braking, the motor is disconnected from the
supply and operated as a generator driven by the kinetic energy of
the rotating parts of the motor and its driven machines.
 Thus the kinetic energy of rotation is converted into electrical
energy, which is dissipated in the external resistance connected
across the motor at the braking instant.

11. 3.Regenerative Braking
 In the previous two methods of electric braking namely plugging and
rheostatic braking, stored energy of the rotating parts of the motor and its
driven machines is wasted whilst in plugging extra energy is drawn during
the braking period and wasted.
 In the regenerative braking the motors remain connected to the supply and
return the braking energy to the supply.
 For regenerative braking it is necessary that traction motors must generate
power at a voltage higher than the supply voltage and at a reasonable
constant voltage.

12. Advantages of Traction Motor
 Cleanliness
 Less starting time
 Less Maintenance cost and time
 High starting Torque
 Braking
 Saving in high grade coal

13. Disadvantages of Traction Motor
 Initial high cost of laying out overhead electric supply system.
 Power failure for few minutes can cause traffic dislocation for
hours.
 Communication lines which usually run parallel to the power supply
lines suffer from electrical interference.
 Electric traction can be used only on those routes which have been
electrified.

14.  The global electric traction motor market is projected to reach USD 22.2 billion by
2027 from an estimated market size of USD 12.3 billion in 2022, at a CAGR of
12.6% during the forecast period.
 The increase in demand for high-performance motors, favorable government
policies and subsidies, and the rise in investments in the railway sector are
expected to drive the electric traction motor market.
 Increased demand for electric vehicles is the major growth opportunity for the
electric traction motor market.
Global Demands of Traction Motor

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