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Total questions: 49
Worksheet time: 25mins
What is the main function of an electric machine?
A. To convert electrical energy into mechanical energy or vice versa
B. To store electrical energy
C. To transmit data signals
D. To protect circuits from overload
32. Which part of a DC motor is responsible for current reversal in the armature winding?
A. Field winding
B. Brushes
C. Commutator
D. Shaft
In a DC motor, what happens to the speed when the supply voltage is increased under constant load
A. Speed decreases
B. Speed remains consta
C. Speed becomes zero
D. Speed increases
Which type of AC motor operates based on the principle of electromagnetic induction?
A. Synchronous motor
E. Induction motor
D. Stepper motor
B. Universal motor
What is the function of the stator in an AC motor?
A. Converts DC to AC
B. Produces a rotating magnetic field
C. Supplies mechanical torque
D. Reduces friction
Which DC motor type has the highest starting torque?
A. DC shunt motor
B. DC separately excited motor
C. DC compound motor
D. DC series motor
What determines the synchronous speed of an AC motor?
A. Rotor resistance
B. Supply voltage
C. Load torque
D. Frequency and number of poles
In an induction motor, slip is defined as:
A. Difference between stator and rotor currents
B. Ratio of output power to input power
C. (Synchronous speed − rotor speed) / synchronous speed
D. Speed of the rotating magnetic field
. What happens to the rotor speed of an induction motor when the load increases?
A. It becomes equal to synchronous speed
B. It decreases slightly
C. It increases
D. It becomes zero
Which component produces the magnetic field in a DC motor?
A. Armature winding
B. Commutator
C. Shaft
Field winding
Which AC motor runs at constant speed regardless of load?
. Induction motor
B. Universal motor
C. Single-phase motor
D. Synchronous motor
What is the main advantage of an induction motor?
A. High starting torque
B. Simple and rugged construction
C. Very high speed control accuracy
D. Requires DC supply
. What type of current is supplied to the stator of an induction motor?
A. Direct current
B. Pulsating current
C. Alternating current
D. Rectified current
What is the function of brushes in a DC motor?
A. Generate magnetic field
B. Cool the motor
C. Reduce vibration
D. Supply current to the rotating armature
Which loss occurs due to resistance of windings in electrical machines?
Mechanical loss
Core loss
Stray los
Copper loss
What is the power factor of an ideal synchronous motor operating without load?
A. Zero
B. Lagging
C. Unity
D. Leading
Which part of an induction motor carries induced current?
A. Stator core
B. Field winding
C. Rotor
D. Shaft
What happens if the supply frequency of an AC motor decreases while voltage remains constant?
A. Speed increases
B. Speed decreases
C. Torque becomes zero
D. Motor stops instantly
Which DC motor is best suited for constant speed applications?
A. DC series motor
B. DC compound motor
C. Universal motor
D. DC shunt motor
What is the main purpose of laminating the core of electrical machines?
A. Increase strength
B. Reduce copper losses
C. Reduce eddy current losses
D. Increase speed
Which AC motor is commonly used in household appliances?
A. Three-phase induction motor
B. Synchronous motor
C. Universal motor
D. Slip-ring motor
What produces torque in an electric motor?
A. Mechanical friction
B. Magnetic interaction between fields
C. Electric resistance
D. Heat generation
In a DC generator, mechanical energy is converted into:
A. Thermal energy
B. Chemical energy
C. Electrical energy
D. Magnetic energy
Which parameter mainly affects the torque of an induction motor?
Supply frequency
Supply frequency
Slip
Number of phases
Which device can operate on both AC and DC supply?
Induction motor
Synchronous motor
Stepper motor
Universal motor
. What is the main purpose of an electric drive system in automated equipment?
A. Convert electrical energy into controlled mechanical motion
B. To store electrical energy
C. To protect electrical circuits
D. To generate electrical signals
Which element of an electric drive directly converts electrical energy into mechanical energy?
B. Electric motor
vC. Power suppl
D. Feedback sensor
What is the main function of a controller in an electric drive system?
A. Increase motor temperature
B. Convert AC to DC
C. Control speed, torque, and direction
D. Reduce mechanical losses
What is the role of a feedback device in a closed-loop electric drive system?
Provide power to the motor
Reduce electrical noise
Convert voltage level
Measure actual output and send it to the controller
Which parameter is typically controlled in an electric drive system?
A. Humidity
B. Light intensity
C. Temperature
D. Speed
What distinguishes a closed-loop electric drive from an open-loop system?
A. Higher power consumption
B. Absence of a motor
C. Use of feedback
D. Lower efficiency
What device is commonly used to control the speed of an AC motor in automated systems?
vA. Transformer
B. Rectifier
C. Variable frequency drive (VFD)
D. Circuit breaker
Which motor is best suited for precise position control in automation?
A. AC induction motor
B. DC shunt motor
C. Universal motor
D. Servo motor
What is the main function of a power converter in an electric drive system?
Measure spee
Control mechanical load
Convert electrical power to required form
Filter noise
Which control method changes motor speed by varying supply frequency?
A. Scalar control
B. Frequency control
C. Voltage control
D. Torque control
What happens to motor torque when supply voltage decreases (other conditions constant)?
A. Torque increases
B. Torque remains constant
C. Torque decreases
D. Torque becomes zero
Which component protects an electric drive system from excessive current?
A. Encoder
B. Sensor
C. Fuse or circuit breaker
D. Controller
What is the function of an encoder in an electric drive system?
A. Increase torque
B. Reduce vibration
C. Supply power
D. Provide position or speed feedback
Which type of load has torque proportional to speed squared?
Constant torque load
Fan or pump load
Shock load
Intermittent load
What is the main advantage of servo drives in automation?
A. Low cost
B. Simple construction
C. High precision and fast response
D. Minimal maintenance
Which signal is typically processed by the drive controller?
A. Mechanical stress
B. Temperature of bearings
C. Position or speed feedback
D. Noise level
What happens if feedback is lost in a closed-loop electric drive?
A. System efficiency increases
B. Motor speed stabilizes automatically
C. Load decreases
D. Drive may operate inaccurately or become unstable
Which drive system is simplest in structure?
Servo drive
. Closed-loop drive
Vector-controlled drive
Open-loop drive
What is the main purpose of automation in electric drive systems?
A. Increase manual control
B. Reduce system safety
D. Improve accuracy, efficiency, and reliability
C. Eliminate electric motors
Which motor is commonly used in conveyor systems with constant speed requirements?
A. Stepper motor
B. AC induction motor
C. Servo motor
D. Universal motor
What does torque represent in an electric drive system?
A. Electrical resistance
B. Rotational force
C. Power loss
D. Voltage drop
Which component links the electric drive to the mechanical system?
A. Controller
B. Sensor
C. Coupling or gearbox
D. Power supply
. What type of control improves efficiency by adjusting both voltage and frequency?
. Scalar control
Manual control
Open-loop control
Vector control
Which system automatically corrects deviations from the set value?
A. Manual drive
Closed-loop drive
Mechanical drive
mergency drive
