All Free Electrical Engineering MCQs with Answers
Every Electrical Engineering question in the bank, across all chapters, each with the correct answer and a written explanation. Free and unlimited, with no account needed.
3,143 questions · page 150 of 158
- A. 6.6 kV
- B. 9.9 kV
- C. 11kV
- D. 13.2kV
Explanation: Generating voltages such as 6.6 kV, 11 kV, and 13.2 kV are commonly used in alternators.
Correct answer: 9.9 kV- A. Carnot cycle
- B. Rankin cycle
- C. Brayton cycle
- D. Dual cycle
Explanation: A gas turbine works on the Brayton cycle: air is compressed, heat is added during combustion, and the hot gases expand through the…
Correct answer: Brayton cycle- A. high
- B. low
- C. remain same
- D. depend on the plan type
Explanation: A high diversity factor means the station's maximum coincident demand is much lower than the sum of individual maximum demands.
Correct answer: low- A. unity
- B. zero
- C. negative.
- D. infinity.
Explanation: Load factor is average load divided by maximum demand. Its ideal maximum is unity, meaning the plant operates at its maximum demand…
Correct answer: unity- A. monograph.
- B. load graph.
- C. discharge graph.
- D. hydro graph
Explanation: The discharge plotted against time is called a hydrograph, which shows how the water flow available to the plant varies over time.
Correct answer: hydro graph- A. radium
- B. cadmium
- C. uranium
- D. all of the above
Explanation: Uranium is the commonly used nuclear reactor fuel because its nuclei can undergo a controlled fission chain reaction.
Correct answer: uranium- A. average load/maximum load.
- B. maximum demand/connected load
- C. connected load/maximum demand.
- D. average load x maximum load
Explanation: Demand factor compares the maximum demand with the total connected load: demand factor = maximum demand / connected load.
Correct answer: maximum demand/connected load- A. super heater
- B. condenser
- C. economizer
- D. chimney
Explanation: The economizer recovers heat from flue gases to preheat the boiler feedwater, improving plant efficiency and reducing fuel consumption.
Correct answer: economizer- A. nuclear power plants
- B. diesel generating plants
- C. thermal power plants
- D. steam power stations
Explanation: Nuclear fuel has very high energy density, so only a small quantity is needed and its transportation requirement is least among the listed…
Correct answer: nuclear power plants- A. induction motors
- B. resistive loads
- C. synchronous Motors
- D. all of the above
Explanation: Induction motors draw magnetizing reactive power, which lowers the supply power factor.
Correct answer: induction motors- A. maximum demand/average load
- B. average load x maximum demand
- C. average load/maximum demand
- D. none of the above
Explanation: Load factor compares the average load carried by a station with its maximum demand: load factor = average load ÷ maximum demand.
Correct answer: average load/maximum demand- A. 532 k cal.
- B. 735 k cal.
- C. 746 k cal.
- D. 860 k cal.
Explanation: One kilowatt-hour equals 3.6 MJ, and 1 kcal is approximately 4.187 kJ; hence 3,600 ÷ 4.187 is about 860 kcal.
Correct answer: 860 k cal.- A. high
- B. low
- C. remain same
- D. none of the above
Explanation: For a given real power, a low power factor requires higher current, increasing conductor and equipment ratings and losses.
Correct answer: high- A. reducing the work done
- B. increasing the rotor speed
- C. reducing the rotor speed
- D. balancing the turbine
Explanation: Compounding divides the steam expansion among several stages so that the excessive velocity or pressure drop of a single stage is avoided.
Correct answer: reducing the rotor speed- A. 0.8 to 1.0
- B. 1.0 to 1.05
- C. 1.1 to 1.5
- D. above 1.5
Explanation: The reheat factor is greater than unity because the cumulative actual stage enthalpy drops exceed the overall isentropic enthalpy drop.
Correct answer: 1.1 to 1.5- A. isentropic heat drop to useful heat drop
- B. adiabatic heat drop to isentropic heat drop
- C. cumulative actual enthalpy drop for the stages to total is isentropic enthalpy heat drop
Explanation: Reheat factor equals the sum of the actual enthalpy drops in all turbine stages divided by the overall isentropic enthalpy drop.
Correct answer: cumulative actual enthalpy drop for the stages to total is isentropic enthalpy heat drop- A. Deaerative heating is done to
- B. heat the water
- C. heat the air in the water
- D. remove dissolved gases in the water
Explanation: Deaerative heating heats feedwater close to its saturation condition so that dissolved oxygen and other corrosive gases are released.
Correct answer: remove dissolved gases in the water- A. to reduce the boiler pressure
- B. to increase the steam temperature
- C. to control the solid concentration in the boiler water by removing some of the concentrated saline water
- D. none of the above
Explanation: Boiler blowdown removes a portion of concentrated boiler water, controlling the buildup of dissolved salts and suspended solids.
Correct answer: to control the solid concentration in the boiler water by removing some of the concentrated saline water- A. 50-75 kg/m per hour
- B. 75-100 kg/m per hour
- C. 100-150 kg/m per hour
- D. 150-200 kg/m2 per hour
Explanation: A traveling-grate stoker commonly burns coal at approximately 150 to 200 kg per square metre of grate area per hour.
Correct answer: 150-200 kg/m2 per hour- A. underfeed stoker
- B. overfeed stoker
- C. any
Explanation: Overfeed stokers suit large boilers burning unpulverised coal because coal is fed above the grate and can be supplied continuously in…
Correct answer: overfeed stoker