All Free Electrical Engineering MCQs with Answers

• A. D.C. shunt motor
• B. D.C. series motor
• C. Squirrel cage induction motor
• D. Slip ring induction motor

Explanation: A squirrel-cage induction motor has relatively low starting torque because its rotor resistance is fixed and usually small, giving a low…

• A. Electric shovels
• B. Cranes
• C. Rolling mills
• D. All of the above

Explanation: Electric shovels, cranes, and rolling mills all have repeated accelerating, loading, unloading, and braking periods.

• A. Pole changing squirrel cage motors
• B. D.C. motors with Ward-leonard con-trol
• C. A.C. slip ring motors with variable resistance
• D. Any of the above

Explanation: Derricks and winches require high starting torque and controllable speed, which can be provided by pole-changing motors, Ward-Leonard DC…

• A. d.c. shunt motor
• B. schrage motor
• C. synchronous motor
• D. slip ring induction motor

Explanation: A slip-ring induction motor provides access to the rotor circuit through slip rings, allowing an injected EMF to control rotor current and…

• A. Slip ring induction motor
• B. Synchronous motor
• C. D.C. shunt motor
• D. Schrage motor

Explanation: A synchronous motor runs at synchronous speed, which is fixed by supply frequency and pole number, so its speed-control range is…

• A. Resistance in rotor circuit
• B. Resistance in stator circuit
• C. Auto-transformer starting
• D. Star-delta starting

Explanation: A squirrel-cage rotor has no accessible external circuit, so resistance cannot be inserted directly into its rotor circuit.

• A. heavy
• B. medium
• C. normal
• D. low

Explanation: A jaw crusher must break and compress hard material, so its motor frequently starts against a heavy load.

• A. Cascade controlled A.C. motor
• B. Slip ring induction motor
• C. Three phase shunt wound com-mutator motor
• D. Any of the above

Explanation: Kiln drives require high starting torque and controlled speed, which can be obtained with cascade-controlled AC motors, slip-ring…

• A. Synchronous motor
• B. Ship ring induction motor
• C. Squirrel cage induction motor
• D. D.C. shunt motor

Explanation: A DC shunt motor provides a broad speed-control range through field or armature-voltage control while maintaining nearly constant torque.

• A. ball or roller
• B. needle
• C. bush
• D. thrust

Explanation: Motor rotors are commonly supported by ball or roller bearings because these bearings carry radial loads with low friction.

• A. 'crowd' motion
• B. angle of swing
• C. cubic metres
• D. travel in metres

Explanation: An excavator’s size is generally specified by its bucket capacity, expressed in cubic metres.

• A. Star-delta
• B. Resistance starting
• C. Auto-transformer
• D. None of the above

Explanation: Star-delta starting requires access to all six ends of the three stator windings so they can first be connected in star and then in delta.

• A. Pulley
• B. Starter
• C. Foundation pedal
• D. Bearings

Explanation: A starter is essential because it limits starting current and provides switching and protection for the motor.

• A. variable torque motor
• B. low torque variable speed motor
• C. self starting type synchronous motor
• D. low noise, slow speed motor

Explanation: A reluctance motor has a salient rotor and operates as a synchronous motor; in its commonly used polyphase form, it can start as an…

• A. is provided with slip rings
• B. requires starting gear
• C. has high cost
• D. is compact

Explanation: A reluctance motor has a simple rotor without windings, slip rings, or permanent magnets, so it is compact and mechanically robust.

• A. Synchronous motor
• B. Reluctance motor
• C. Series motor
• D. Shunt motor

Explanation: Reluctance motors are suitable for textile and synthetic-fibre mills because they provide nearly constant-speed operation with a simple…

• A. Induction motor
• B. Synchronous motor
• C. Capacitor start single phase motor
• D. Any of the above

Explanation: Induction motors are commonly used for elevators because they are rugged and provide suitable starting and speed characteristics…

• A. Synchronous motor
• B. Schrage motor
• C. Induction motor
• D. Universal motor

Explanation: A synchronous motor runs at synchronous speed, which is fixed by supply frequency and the number of poles, so its speed remains…

• A. Flux
• B. Armature current
• C. Flux and armature current
• D. Speed

Explanation: The DC motor torque relation is T ∝ ΦIa, so starting torque depends on flux and armature current.

• A. Paper mills
• B. Grinding mills
• C. Air-conditioners
• D. Lifts and hoists

Explanation: Lifts and hoists repeatedly start, stop, and reverse while handling changing loads, so their motors must tolerate frequent switching and…