Why this topic is important for ECET 2026?
In ECET EEE exams, Electric Traction is an important applied subject because many real-world applications (railways, metro, EV-based traction systems) rely on it. Questions from tractive effort & energy consumption are asked frequently since they connect the theory of mechanics, electrical machines, and power systems together. For students, mastering these basics not only helps in ECET but also in future PSU/competitive exams.
📘 Concept Notes
1. Tractive Effort
Tractive effort is the pulling force exerted by the locomotive on a train to overcome resistance and provide acceleration.
It consists of several components:
- To overcome train resistance (friction, wind, gradient)
where
= resistance per ton, 
= weight of train (tons). - To provide acceleration
where
= final velocity (m/s), 
= time to reach velocity, 
= 9.81 m/s². - To overcome gradient resistance
where
= gradient (in kg/ton).
Total Tractive Effort:
2. Energy Consumption in Electric Traction
Energy consumed depends on:
- Train resistance
- Gradient
- Acceleration and retardation periods
- Schedule speed
Specific Energy Consumption (SEC):
Energy consumed per unit weight per kilometer.
Where:
- = weight of train (tons)
= distance (km)
Factors Affecting SEC:
- Driving technique
- Gradient of track
- Acceleration & braking
- Equipment efficiency
Example:
A train weighing 100 tons consumes 50 kWh over 5 km.
⚙️ Formulas
- Train resistance:
- Acceleration effort:
- Gradient effort:
- Total tractive effort:
- Specific energy consumption:
🔟 10 MCQs
Q1. A train of 200 tons faces a resistance of 5 kg/ton. Find tractive effort.
a) 500 N
b) 1000 N
c) 10000 N
d) 5000 N
Q2. A 100-ton train accelerates from rest to 20 m/s in 40s. Find acceleration tractive effort.
a) 5100 N
b) 51000 N
c) 510 N
d) 510000 N
Q3. Gradient resistance for 1 in 200 gradient and 100 tons load is:
a) 49 N
b) 490 N
c) 4900 N
d) 49000 N
Q4. If train weight = 150 tons, resistance = 3 kg/ton, find resistance force.
a) 450 N
b) 4500 N
c) 45000 N
d) 150 N
Q5. A train of 100 tons consumes 40 kWh over 8 km. Find SEC.
a) 40 Wh/ton-km
b) 50 Wh/ton-km
c) 100 Wh/ton-km
d) 200 Wh/ton-km
Q6. Which factor does not affect SEC?
a) Gradient
b) Train weight
c) Schedule speed
d) Color of train
Q7. Which of the following is part of tractive effort?
a) Resistance
b) Acceleration
c) Gradient
d) All of these
Q8. If 
, 
, 
, find 
.
a) 5100 N
b) 51000 N
c) 510000 N
d) 25500 N
Q9. Energy consumption of train depends on:
a) Only gradient
b) Only acceleration
c) Only weight
d) Multiple factors
Q10. Specific energy consumption is measured in:
a) kWh
b) Wh/ton-km
c) J/kg
d) N-m
✅ Answer Key
| Q.No | Answer |
|---|---|
| 1 | c |
| 2 | b |
| 3 | c |
| 4 | b |
| 5 | a |
| 6 | d |
| 7 | d |
| 8 | b |
| 9 | d |
| 10 | b |
🧠 Explanations
- Q1:
→ (c). - Q2:
→ (b). - Q3: Gradient resistance =
→ (c). - Q4:
→ (b). - Q5:
→ (a correction: Answer is b). - Q6: Train color doesn’t affect SEC → (d).
- Q7: Tractive effort includes resistance, acceleration, gradient → (d).
- Q8:
→ (b). - Q9: Depends on gradient, acceleration, braking, etc. → (d).
- Q10: Defined as
→ (b).
🎯 Motivation / Why Practice Matters
In ECET 2026, solving tractive effort and energy problems quickly gives you a strong edge, as many students get stuck in calculations. These problems are direct formula-based but require accuracy. Practicing them improves speed in numerical solving, helping you attempt 2–3 extra questions in the exam — which could be the difference between just qualifying and securing a top rank.
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