All Free Electrical Engineering MCQs with Answers

• A. Plugging braking
• B. Rheostatic braking
• C. Regenerative braking
• D. None of the above

Explanation: Plugging applies a reverse torque by reversing the motor connections, producing rapid braking and bringing the locomotive to a dead stop.

• A. 12 V
• B. 24 V
• C. 220 V
• D. 600 to 750 V

Explanation: D.C. suburban railway systems commonly use a third-rail or overhead supply in the range of 600 to 750 V.

• A. more on steeper gradient
• B. more with high train resistance
• C. less if distance between stops is more
• D. all of the above

Explanation: Energy consumption rises with steeper gradients and greater train resistance, while longer distances between stops reduce repeated…

• A. greased
• B. wet
• C. sprayed with oil
• D. cleaned with sand

Explanation: Sand removes moisture and increases friction between the wheel and rail, raising the coefficient of adhesion.

• A. Cascade control
• B. Pole changing
• C. Rheostat control
• D. Combination of cascade and pole changing

Explanation: Rheostat or rotor-resistance control wastes substantial power as heat in the external resistance, so its efficiency is low.

• A. distance between the stops is more
• B. maximum speed reached is high
• C. acceleration and retardation rates are low
• D. all of the above

Explanation: Main-line trains have widely spaced stops, allowing higher speeds, while their acceleration and retardation rates are lower than those…

• A. Main line service
• B. Urban service
• C. Sub-urban service
• D. Urban and sub-urban service

Explanation: The quadrilateral speed-time curve is used for urban and suburban services, where stops are relatively close and the train may have…

• A. Hydraulic system
• B. Pneumatic system
• C. Vacuum system
• D. None of the above

Explanation: Steam locomotives traditionally use vacuum brakes, in which atmospheric pressure applies the brakes when vacuum is reduced.

• A. Engine power
• B. Track curves
• C. Passenger Discomfort
• D. Track sizeCompare Power Rates

Explanation: Suburban trains carry standing and seated passengers and make frequent stops, so excessive acceleration or braking would cause discomfort.

• A. 0.12
• B. 0.25
• C. 0.40
• D. 0.75

Explanation: A normal wheel-to-rail coefficient of adhesion is commonly taken as about 0.25 under ordinary conditions.

• A. it has longer free running period
• B. it has longer coasting period
• C. accelerating and braking periods are comparatively smaller
• D. all of the above

Explanation: Main-line trains travel longer distances between stations, so their speed-time curves have longer free-running and coasting intervals…

• A. speed
• B. (speed)
• C. (speed)
• D. 1/speed

Explanation: Air resistance on a train is approximately proportional to the square of its speed, so doubling speed produces about four times the…

• A. Jolting and skidding
• B. Hammer blow
• C. Pitching
• D. All of the above

Explanation: The pulsating torque of steam locomotives produces uneven tractive effort, leading to jolting and possible wheel skidding.

• A. Sand on rails
• B. Dew on rails
• C. Oil on the rails
• D. both B. and C.

Explanation: Dew forms a water film and oil acts as a lubricant, both of which reduce wheel-to-rail adhesion.

• A. overcome the gravity component of train mass
• B. overcome friction, windage and curve resistance
• C. accelerate the train mass
• D. do all of the above

Explanation: Tractive effort must overcome the train’s gravity component, running resistances such as friction, windage and curves, and the additional…

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

Explanation: For the same axle load, AC locomotives can develop greater tractive effort because their traction-control systems provide better adhesion…

• A. 60 kmph
• B. 75 kmph
• C. 100 kmph
• D. more than 100 kmph

Explanation: A superfast train is conventionally defined in this classification as one whose speed exceeds 100 km/h.

• A. Regenerative braking on electric locomotives
• B. Vacuum braking on diesel locomotives
• C. Vacuum braking on steam locomotives
• D. All braking systems are equally costly

Explanation: Regenerative braking requires additional control and power-handling equipment so that generated energy can be returned to the supply…

• A. D.C. shunt motor
• B. D.C. series motor
• C. A.C. three phase motor
• D. AC. single phase capacitor start motor

Explanation: A DC series motor gives very high starting torque and its speed naturally varies with load, making it well suited to tramway traction.

• A. single cylinder double acting steam engine
• B. double cylinder, single acting steam engine
• C. double cylinder, double acting steam engine
• D. single stage steam turbine

Explanation: Traditional steam locomotives use double-acting cylinders, in which steam produces a power stroke on both sides of the piston.