The document discusses electric traction for train services. It describes the different types of train services as urban/city, suburban, and main line services. It then explains the speed time curve which plots the instantaneous speed of a train over time and includes periods of acceleration, reaching maximum speed, coasting, and braking. It notes the speed time curve can be simplified, trapezoidal, or quadrilateral in shape. Finally, it defines maximum, average, and schedule speeds for train services.

1. ELECTRIC TRACTION
- Mr. V. S. Wadkar

2. TOPICS TO BE DISCUSSED
• Type of Services
• Speed Time Curve
• Maximum Speed, Average Speed &
Schedule Speed

3. Types of Services
• Urban or city services-
Small distance between stations, High
acceleration
• Sub urban services-
Small distance between stations, High
acceleration
• Main line services-
Long distance between stations, Moderate
acceleration

4. Speed Time Curve
• Curve of instantaneous speed of train versus time

5. Speed Time Curve
Curve consists following periods.
• Notching up period or Constant acceleration
• Acceleration Period or Speed curve running
• Free run or constant speed period
• Coasting period
• Retardation or braking period

6. Speed Time Curve
• Notching up period or Constant acceleration

7. Speed Time Curve
• Acceleration Period or Speed curve running

8. Speed Time Curve
• Free run or constant speed period

9. Speed Time Curve
• Coasting period

10. Speed Time Curve
• Retardation or braking period

11. Speed Time Curve
• Simplified speed time curve

12. Speed Time Curve
• Trapezoidal speed time curve

13. Speed Time Curve
• Quadrilateral speed time curve

14. ELECTRIC TRACTION SYSTEM
• Crest or Maximum Speed
• Average Speed
-Ratio of distance between stops to actual
time of run
• Schedule Speed
-Ratio of distance between stops to total
time of run