Nilgiri
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:Bullish on India's growth, major French companies will be investing about EUR 8 billion in the country in next few years. French majors had already invested EUR 20 billion in the country accounting for the third largest FDI inflow from the European country.
Ok as promised, here is a technical article explaining where did the Horse-power rating of locomotives for DFC have come from. I'm writing it down in number of posts owing to image limitation.
PART 1
Definitions
Locomotive capability and Train Resistance Curve
A locomotive has a limited pulling capacity (referred to as Traction effort or TE hereafter), which is usually measured in terms of kilo newtons (kN) or Tons (T) (1 Ton=10 kN). This capability however is not fixed and varies with speed. This can be visualized when you drive a car. At low gearing, torque generated by engine is high, which allows you to climb on a steep road or carry heavier load but at a slow speed. Alternately if you want to drive faster, you have to lower the weight.
A locomotive works similarly and the reason for that is that at higher speeds, the resistance from train tries to slow down the train. The resistance is a function of v^2 (where v is the velocity).
When you plot down the Traction Effort with speed, you get a curve which is called TE curve for a locomotive.
View attachment 327450
this is TE curve for our WDG 4 (4500 HP 3 phase diesel locomotive)
On the same curve if you plot Train Resistance (TR) curve, you'll get something like this.
View attachment 327448
Please note here that TR is a function of slope of track and load. In railway terms, slope is called gradient and is usually defined as 1:abc (where abc is a number). This means a slope equal to an angle of sine (inverse) (1/abc). So bigger is abc (denominator, gentler is the slope or gradient).
Higher the gradient or load, steeper will be TR curve.
View attachment 327457
Balancing Speed
Now the point where TR arc cuts TE curve is the speed, that locomotive can run at maximum. Essentially this is the maximum speed a locomotive can sustain on a certain slope and load. This speed is called Balancing Speed.
In above picture, where ever the colored lines are cutting Thick black line (TE curve), the corresponding value on x axis is Balancing Speed.
& in continuation of above, higher the load and/or gradient, lower will be the balancing speed.
Starting Tractive Effort and Continuous Tractive Effort
When a train starts from standstill, it has to break down the rolling friction. At this point the pulling force provided by locomotive is highest and is called Starting TE. As speed increases, we shift to right and the applied force reduces (as TR increases). Usually based on friction or wheel adhesion, a lower value of tractive effort is always available and this is called Continuous Tractive effort. This value lies usually on the curved part of TE curve.
View attachment 327463
Effort details for WDG 4
The above definitions will help us understand how a locomotive is selected based on track conditions (Gradient and adhesion), load to be carried and maximum speed required.
PART 2
Dedicated freight Corridor Requirements
DFC is designed for much higher axle load (initially 25 Tons and upgradable to 30 tons later). What this means is that each axle of a bogie can bear higher load and at higher speed. This means two things. Assume two trains of equal bogies (say 10 each). One track allows 20T axle load (Train A) and other 25 tons (Train B). Each bogie consists of 4 axles (typical Indian Freight wagon).
Train A will be able to carry 20*4*10 (Axle load*No. of Axles*number of Bogies)=800 Tons.
Train B will carry 25*4*10=1000 Tons.
So you can note that by simply increasing axle load by 5 tons, train capacity increases by 25% ..........(i)
Now assume Train A moves at a speed of 30 kph (Typical average speed of Indian Freight Train)and Train B at 65 kph (proposed average speed for DFC). Now between points X and Y, Train B (remember it already is carrying more load) will take half the time as compared to Train A. Simply put, by the time Train A reaches from point X to Y, Train B would have covered its round journey from point X to Y and back to X. So heavier load moved in lesser time. In railway terminology this is called Throughput. The heavier and Faster moving train will always create a higher capacity of load movement of higher Throughput. ............(ii)
View attachment 327496
If you combine (i) and (ii), this is exactly what DFC is trying to achieve.
& what it would mean is that the cost of transportation would come down as heavier freight can be moved quickly. No wonder DFC is speculated to add atleast 1% to GDP when fully functional.
View attachment 327497
View attachment 327499
Let me check.
This was an older documentary I think from the mid 90s sometime I believe.