Q1. The correct sequence of an electric power system is:
A. Distribution → Transmission → Generation
B. Generation → Transmission → Distribution
C. Transmission → Generation → Distribution
D. Generation → Distribution → Transmission
Correct Option: 2
Explanation:
Electrical energy is first generated at power stations, then transmitted at high voltage to reduce losses, and finally distributed at utilization voltage to consumers. Hence, the correct sequence is Generation → Transmission → Distribution.
Q2. Which element is used to step up voltage at generating station?
A. Distribution transformer
B. Auto-transformer
C. Step-up power transformer
D. Potential transformer
Correct Option: 3
Explanation:
Voltage is stepped up at the generating station using a step-up power transformer to reduce current and hence minimize I²R transmission losses.
Q3. Variable load on a power station is mainly due to:
A. Weather only
B. Consumer demand variation
C. Generator losses
D. Transmission voltage
Correct Option: 2
Explanation:
Load varies throughout the day due to changes in domestic, commercial, and industrial consumer demand, leading to variable load on the power station.
Q4. The load which remains constant throughout the day is called:
A. Peak load
B. Variable load
C. Base load
D. Maximum demand
Correct Option: 3
Explanation:
Base load is the minimum load that remains almost constant over a long duration and is always present on the power system.
Q5. A load curve represents the variation of:
A. Voltage vs time
B. Power vs time
C. Current vs time
D. Energy vs time
Correct Option: 2
Explanation:
A load curve is a graphical representation of power demand (kW or MW) versus time, showing how load changes during a period.
Q6. Area under load curve gives:
A. Maximum demand
B. Load factor
C. Energy generated
D. Plant capacity
Correct Option: 3
Explanation:
The area under the load curve represents the total electrical energy generated over the considered time period.
Q7. Daily load curve is useful to determine:
A. Tariff only
B. Size of conductor
C. Energy generated in one day
D. Transmission losses
Correct Option: 3
Explanation:
The area under a daily load curve gives the total energy generated in 24 hours, useful for operational planning.
Q8. Load factor is defined as:
A. Average load / Maximum demand
B. Maximum demand / Average load
C. Installed capacity / Peak load
D. Energy / Time
Correct Option: 1
Explanation:
Load factor indicates utilization of the power station and is defined as the ratio of average load to maximum demand.
Q9. Which factor indicates utilisation of plant capacity?
A. Diversity factor
B. Load factor
C. Demand factor
D. Capacity factor
Correct Option: 2
Explanation:
Load factor shows how uniformly the plant capacity is utilized over a period. Higher load factor means better utilization.
Q10. Capacity factor is always:
A. Greater than 1
B. Less than or equal to load factor
C. Greater than load factor
D. Equal to diversity factor
Correct Option: 2
Explanation:
Since installed capacity is always greater than or equal to maximum demand, capacity factor is always less than or equal to load factor.
Q11. Maximum demand on a power station is:
A. Average load
B. Connected load
C. Highest load during a given period
D. Installed capacity
Correct Option: 3
Explanation:
Maximum demand is the highest load recorded on the power station during a specified period and decides equipment sizing.
Q12. Demand factor is always:
A. Greater than 1
B. Equal to 1
C. Less than 1
D. Zero
Correct Option: 3
Explanation:
Demand factor is the ratio of maximum demand to connected load and is always less than 1 because connected load exceeds maximum demand.
Q13. Diversity factor is:
A. Always less than 1
B. Always equal to 1
C. Always greater than 1
D. Sometimes zero
Correct Option: 3
Explanation:
Since all consumers do not reach peak demand simultaneously, diversity factor is always greater than 1.
Q14. Annual energy generated by a station depends on:
A. Maximum demand only
B. Load factor only
C. Maximum demand and load factor
D. Installed capacity only
Correct Option: 3
Explanation:
Annual energy generated is given by: Energy = Maximum Demand × Load Factor × 8760 hours.
Q15. A power station has maximum demand of 50 MW and load factor of 0.6. Annual energy generated is:
A. 262.8 GWh
B. 219 GWh
C. 180 GWh
D. 300 GWh
Correct Option: 1
Explanation:
Annual Energy = 50 × 0.6 × 8760 = 262800 MWh = 262.8 GWh.
Q16. The base load power stations are generally:
A. Diesel plants
B. Gas turbine plants
C. Thermal / Nuclear plants
D. Emergency plants
Correct Option: 3
Explanation:
Thermal and nuclear plants are best suited for base load operation due to low running cost and continuous operation.
Q17. Which load curve is useful for tariff calculation?
A. Daily load curve
B. Monthly load curve
C. Annual load curve
D. Duration load curve
Correct Option: 4
Explanation:
Load duration curve helps in tariff calculation and selection of base-load and peak-load plants.
Q18. Installed capacity of a power station is always:
A. Less than maximum demand
B. Equal to maximum demand
C. Greater than maximum demand
D. Zero
Correct Option: 3
Explanation:
Installed capacity is kept higher than maximum demand to ensure reliability and provide reserve margin.
Q19. If a station generates 4×10⁶ kWh annually and maximum demand is 1000 kW, load factor is:
A. 0.23
B. 0.46
C. 0.75
D. 1
Correct Option: 2
Explanation:
Average Load = (4×10⁶) / 8760 = 456.6 kW. Load Factor = 456.6 / 1000 ≈ 0.46.
Q20. Station has installed capacity of 40 MW, maximum demand 30 MW and annual energy generation of 157.68 GWh. Capacity factor is:
A. 0.45
B. 0.60
C. 0.75
D. 0.90
Correct Option: 1
Explanation:
Capacity Factor = Annual Energy / (Installed Capacity × 8760) = 157680 / (40 × 8760) = 0.45.