Q1. A diesel power station is generally preferred for:
A. Base load operation
B. Peak load operation
C. Continuous heavy load
D. Nuclear backup
Correct Option: 2
Explanation:
Diesel power stations can start quickly and reach full load in a short time, making them suitable for peak load and standby operation. Due to high fuel cost, they are not economical for base load operation.
Q2. The main prime mover used in a diesel power station is:
A. Steam turbine
B. Gas turbine
C. Diesel engine
D. Hydraulic turbine
Correct Option: 3
Explanation:
In a diesel power station, chemical energy of diesel fuel is converted into mechanical energy by a diesel engine, which drives the alternator.
Q3. Which of the following is NOT a component of diesel power station?
A. Fuel injection system
B. Air filter
C. Boiler
D. Exhaust system
Correct Option: 3
Explanation:
A boiler is used only in steam power plants. Diesel power stations do not involve steam generation.
Q4. Overall efficiency of a diesel power station is approximately:
A. 15–20%
B. 25–30%
C. 35–40%
D. 50–60%
Correct Option: 3
Explanation:
Diesel power stations have higher efficiency than steam plants due to direct conversion of fuel energy into mechanical energy and absence of condenser losses.
Q5. In a diesel power station, starting is usually done by:
A. Steam injection
B. Battery or compressed air
C. Hydraulic pressure
D. Grid supply
Correct Option: 2
Explanation:
Diesel engines require an external starting system such as batteries or compressed air to initiate rotation until combustion becomes self-sustaining.
Q6. Major disadvantage of diesel power plant is:
A. High initial cost
B. Long starting time
C. High running cost
D. Low efficiency
Correct Option: 3
Explanation:
Diesel fuel is expensive and maintenance cost is high, resulting in high operating cost compared to other power plants.
Q7. Diesel power plants are most suitable for:
A. Large grid stations
B. Remote locations
C. Base load plants
D. Nuclear replacement
Correct Option: 2
Explanation:
Diesel plants are compact, easy to install, and suitable where grid supply is unavailable, such as remote and isolated locations.
Q8. Which fuel is used in a gas turbine power plant?
A. Coal
B. Diesel only
C. Natural gas / light oil
D. Uranium
Correct Option: 3
Explanation:
Gas turbine plants use clean and easily combustible fuels such as natural gas, kerosene, or light diesel oil.
Q9. Gas turbine power plant works on which cycle?
A. Rankine cycle
B. Otto cycle
C. Brayton cycle
D. Diesel cycle
Correct Option: 3
Explanation:
Gas turbine power plants operate on the Brayton cycle involving constant pressure heat addition.
Q10. Main advantage of gas turbine plant over diesel plant is:
A. Higher efficiency
B. Lower fuel cost
C. Quick starting & compact size
D. Lower temperature operation
Correct Option: 3
Explanation:
Gas turbine plants are light in weight, compact, and can start very quickly, making them suitable for peak load and emergency operation.
Q11. In gas turbine power plant, compressor is used to:
A. Increase fuel pressure
B. Increase air pressure
C. Reduce exhaust loss
D. Cool turbine blades
Correct Option: 2
Explanation:
The compressor increases the pressure of air before combustion to improve efficiency and turbine output.
Q12. Which component converts thermal energy into mechanical energy in gas turbine plant?
A. Compressor
B. Combustion chamber
C. Turbine
D. Alternator
Correct Option: 3
Explanation:
Hot gases expand in the turbine and convert thermal energy into mechanical shaft power.
Q13. Efficiency of simple gas turbine plant is usually:
A. 10–15%
B. 15–20%
C. 25–30%
D. 45–50%
Correct Option: 2
Explanation:
Simple gas turbine plants have low efficiency due to high compressor power consumption and exhaust losses.
Q14. Which method improves gas turbine efficiency?
A. Intercooling
B. Reheating
C. Regeneration
D. All of the above
Correct Option: 4
Explanation:
Intercooling reduces compressor work, reheating increases turbine output, and regeneration recovers exhaust heat, all improving efficiency.
Q15. A diesel power station has an overall efficiency of 30%. Heat input required to generate 1 kWh is:
A. 2866 kcal
B. 3000 kcal
C. 2867 kcal
D. 2500 kcal
Correct Option: 3
Explanation:
Heat input = Electrical output / Efficiency = 860 / 0.30 ≈ 2867 kcal.
Q16. A gas turbine develops 5 MW power with efficiency 20%. Heat supplied per hour is:
A. 21.5 × 10⁶ kcal
B. 25 × 10⁶ kcal
C. 18 × 10⁶ kcal
D. 15 × 10⁶ kcal
Correct Option: 1
Explanation:
Heat input = 5 / 0.20 = 25 MW = 25 × 860 × 10³ kcal/hr = 21.5 × 10⁶ kcal/hr.
Q17. If diesel CV = 11000 kcal/kg and efficiency = 35%, fuel consumption per kWh is:
A. 0.22 kg
B. 0.25 kg
C. 0.28 kg
D. 0.30 kg
Correct Option: 1
Explanation:
Fuel required = (860 / 0.35) / 11000 ≈ 0.223 kg per kWh.
Q18. A gas turbine plant produces 10 MW with efficiency 25%. Heat input per second is:
A. 40 MW
B. 35 MW
C. 25 MW
D. 50 MW
Correct Option: 1
Explanation:
Heat input = Output / Efficiency = 10 / 0.25 = 40 MW.
Q19. A diesel generator delivers 1 MW at efficiency 40%. Fuel energy input is:
A. 2.5 MW
B. 2 MW
C. 3 MW
D. 1.5 MW
Correct Option: 1
Explanation:
Input power = Output / Efficiency = 1 / 0.40 = 2.5 MW.
Q20. Which statement is TRUE for gas turbine power plants?
A. High efficiency at part load
B. Requires condenser
C. Lower efficiency at part load
D. Uses Rankine cycle
Correct Option: 3
Explanation:
Gas turbine plants show poor efficiency at part load due to high fixed compressor power and reduced turbine efficiency.