Free Power Systems MCQs with Answers

• A. 0.5 lagging
• B. 0.5 leading
• C. 0.95 lagging
• D. 0.95 leading

Explanation: A consumer generally operates most economically at a high power factor, commonly taken as about 0.95 lagging.

• A. High maintenance cost
• B. Continuous losses in motor
• C. Noise
• D. All of the above

Explanation: A synchronous condenser has rotating parts, so it requires more maintenance, produces continuous motor losses, and may create operating…

• A. at the receiving end
• B. at the sending end
• C. either A. or (b)
• D. none of the above

Explanation: Reactive-power compensation is most effective when installed near the receiving end or load, where it reduces the reactive current carried…

• A. Phase advancers
• B. Synchronous compensators
• C. Static capacitors
• D. Any of the above

Explanation: Phase advancers, synchronous compensators, and static capacitors all supply or reduce the reactive power demanded by inductive loads.

• A. It should run at high speed
• B. It should produce high voltage
• C. It should be small in size
• D. It should be capable of starting quickly

Explanation: A peak-load plant operates for short periods and must respond rapidly when demand rises.

• A. Nuclear power plant
• B. Steam turbine plant
• C. Pumped storage plant
• D. None of the above

Explanation: Pumped-storage plants store energy during off-peak periods and release it rapidly during demand peaks, making them particularly suited to…

• A. Thermal power plant
• B. Diesel power plant
• C. Nuclear power plant
• D. Hydro-electric power plant

Explanation: Diesel power plants use compact, modular generating units and can be installed comparatively quickly.

• A. diesel power plants
• B. nuclear power plants
• C. hydro-electric power plants
• D. thermal power plants

Explanation: Large thermal plants commonly consume huge quantities of coal or other fuel, making fuel transport a major logistical problem.

• A. Diesel engine plant
• B. Nuclear power plant
• C. Gas turbine plant
• D. Pumped storage plant

Explanation: Nuclear plants have high capital cost, low running cost, and are best operated continuously, so they are normally assigned base load.

• A. firm power
• B. cold reserve
• C. hot reserve
• D. spinning reserve

Explanation: Spinning reserve is generating capacity already synchronized with and connected to the bus bars, so it can accept load immediately.

• A. positive
• B. negative
• C. zero
• D. any of the above

Explanation: Salvage value depends on the plant's remaining value and disposal cost: it may be positive, zero, or effectively negative when dismantling…

• A. Exhaust fan
• B. Lathe machine
• C. Welding transformer
• D. All of the above

Explanation: A welding transformer produces a fluctuating load because the welding arc is repeatedly struck, interrupted, and varied during operation.

• A. peak load plant
• B. base load plant
• C. stand-by plant
• D. spinning reserve plant
• E. any of the above

Explanation: Nuclear stations are designed for continuous operation because their fuel and operating characteristics favour steady generation rather…

• A. sinking fund depreciation
• B. straight line depreciation
• C. reducing balances depreciation
• D. none of the above

Explanation: In the sinking-fund method, interest earned on earlier deposits contributes to the required depreciation fund, so the annual deposit…

• A. fixed charges
• B. semi-fixed charges
• C. running charges
• D. all of the above

Explanation: The annual cost of operating a power plant is divided into fixed charges, semi-fixed charges, and running charges.

• A. equal to unity
• B. less than unity
• C. more than unity
• D. none of the above

Explanation: Utilization factor is the ratio of maximum demand to the plant's rated capacity.

• A. nuclear power plant
• B. hydro power plant
• C. diesel power plant
• D. both B and C
• E. none of the above

Explanation: Diesel and hydroelectric plants can be brought into service very quickly, unlike nuclear plants, which require lengthy starting and…

• A. diesel engine
• B. hydraulic turbine
• C. gas turbine
• D. steam turbine
• E. any of the above

Explanation: Generating stations may use diesel engines, hydraulic turbines, gas turbines, or steam turbines as their prime movers, depending on the…

• A. dependent upon the energy consumed
• B. dependent upon the maximum demand of the consumer
• C. both A and B
• D. neither A nor B

Explanation: In a two-part or Hopkinson tariff, the demand charge is based on the consumer's maximum demand, usually measured in kW or kVA.

• A. the capital cost divided by number of year of life
• B. the capital cost minus the salvage value, is divided by the number of years of life
• C. increasing a uniform sum of money per annum at stipulated rate of interest
• D. none of the above

Explanation: Straight-line depreciation spreads the depreciable amount uniformly over the plant life.