Traction motors.pptx

traction

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. Three Phase Induction Motors DC Series Traction Motor 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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