Pages

18/03/2021

Speed - time Curve of Train

In this theory, the speed time curve of the train is discussed. The curve between speed in km per hour ( Y – axis ) and time in second on X – axis is known as speed – time curve of the train.

Importance of speed time curve

  • It gives completes information regarding motion of the train.
  • It gives information about speed of train at particular time.
  • It gives information about acceleration time, free running time and retardation time of the train.
  • The area covered by the speed – time curves gives information about distance covered by the train. 

Trapezoidal Speed time Curve

The speed time curve mainly consists of

Constant acceleration ( 0 to t1 )

  • The current is maintained approximately constant and voltage across motor increases step by step during notching period ( 0 to t1 ) . 
  • As the tractive effort remains constant during this period, the acceleration also remains constant.



speed-time-curve-of-train.png

Acceleration Running period ( t1 to t2 )

  • The voltage across motor is kept remains constant and current starts to decrease with increase in the speed according to characteristic of DC motor. 
  • The current taken by the motor remains constant after some time.

                                     N α ( Eb / Ia )

Free running period ( t2 to t3 )

  • The train attains maximum speed at the end of time t2
  • The train runs with constant speed after time t2
  • The motor draws constant power from the supply.

Coasting ( t3 to t4 )

  • The power supply is cut off and train is allowed to run under its own momentum after free running period ( t2 to t3 ). 
  • The speed of the train starts to decrease due to resistance of motion of train. 
  • The rate of decrease of speed during coasting period is known as coasting retardation.

Retardation ( t4 to t5 )

  • The brake is applied to train at the end of coasting period ( t4 ). 
  • The speed of train decreases rapidly and finally reduces to zero during retardation period.


You may also like :

Calculation of Sag in the transmission line

What do you mean by inter connector distributor?

Compare base load and peak load

Minimum distance between underground cable and earth surface

No comments:

Post a Comment