Factors Affecting the Schedule Speed of an Electric Train

Electric TractionElectric DrivesUtilisation of Electrical PowerPower System Engineering

Schedule Speed of an Electric Train

The schedule speed of an electric train is defined as the ratio of the distance covered between two stops to the actual time of the run including the time for stop. The schedule speed is denoted by VS and is given by,

$$\mathrm{\mathrm{Schedule\: speed},\mathit{V_{\mathit{S}}}\:=\:\frac{\mathrm{Distance \:between\: two\: stops(\mathit{D})}}{Actual\: run\: time(\mathit{T_{\mathrm{run}}})\:+\:Time \:for\: stop(\mathit{T_{\mathrm{stop}}})}\:\:\:\cdot \cdot \cdot \mathrm{\left ( \mathrm{1} \right )}}$$

$$\mathrm{\therefore \mathrm{Schedule\: speed},\mathit{V_{\mathit{S}}}\:=\:\frac{\mathrm{Distance \:between\: two\: stops(\mathit{D})}}{Schedule\: time (\mathit{T_{S}})}\:\:\:\cdot \cdot \cdot \mathrm{\left ( \mathrm{2} \right )}}$$

Where, TS is the schedule time in hours.

Factors Affecting the Schedule Speed

The factors that affect the schedule speed of an electric train are described as follows −

Crest Speed or Maximum Speed

The crest speed is the maximum speed which affects the schedule speed of the train for constant acceleration, retardation and distance between the two stops.

If the crest speed of the train increases, the actual running time of it decreases, hence the high crest speed of the train will increase its schedule speed (refer Equation-1). Also, the effect of crest speed on the schedule speed is considered only for long run duration.

Acceleration

If the distance between two stops and the crest speed of the train be maintained constant and the acceleration of the train increases, then the running time of the train decreases. Hence, according to Equation (1), the increase in the acceleration will increase the schedule speed of the train.

Braking Retardation

If the breaking retardation of the train is high, then it leads to the reduction of the total running time of the train. Therefore, if the distance between two stops is small, then the high braking retardation will cause high schedule speed of the train.

Note - The variations in the acceleration and braking retardation of the train affect the schedule speed in case of shorter run as compared to longer run.

Distance between the Stops

When the distance between the two stops is long, then the running time of the train is less. Consequently, the schedule speed of the train will be high.

Duration of Stops

For a given average speed, if the duration of stop reduces, then the schedule speed increases. In other words, if the duration of stops is more, then the running time of the train will be less which results in the low schedule speed.

The duration of stops affects the schedule speed more in the case of shorter duration as compared to longer duration this is due to the fact that the duration of stop for urban and suburban traction services is very small. For main line service, the distance between two stations is long, then the duration of stop less affects the schedule speed.

raja
Updated on 28-Apr-2022 08:20:58

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