SACA C-202 ELECTRIC MOTOR CONTROL SYSTEMS – FULL
PRACTICE EXAM QUESTIONS WITH ANSWERS AND
RATIONALES
Section A: Motor Theory & Safety
1. Which of the following is the most common type of motor used in industrial
applications?
A) Single-phase AC motor
B) Three-phase AC motor
C) DC series motor
D) Stepper motor
Rationale: Three-phase AC motors are preferred in industry for efficiency and torque
consistency.
2. What is the main purpose of a motor overload relay?
A) To start the motor
B) To protect the motor from overheating
C) To reverse motor direction
D) To regulate voltage
Rationale: Overload relays detect excessive current that can overheat the motor and interrupt the
circuit.
3. Before performing maintenance on a motor control system, the first step is:
A) Wear gloves
B) Turn off the motor
C) Lockout/tagout the circuit
D) Test the motor with a multimeter
Rationale: Lockout/tagout ensures that the circuit cannot be energized accidentally, protecting
personnel.
4. A bimetallic overload relay works by:
A) Using magnetic fields to detect current
B) Expanding metal strips that bend with heat caused by excess current
C) Using a timer relay to delay trips
D) Sensing voltage drop across windings
, Rationale: Bimetallic strips bend with heat to mechanically open the contact when the current is
too high.
5. Which type of switch is often used for emergency motor shutdown?
A) Selector switch
B) Push button (Start)
C) Push button (Stop/E-Stop)
D) Limit switch
Rationale: Stop or emergency-stop buttons are designed for quick and safe motor shutdown.
Section B: Motor Starters & Control Devices
6. What is the main advantage of a direct-on-line (DOL) starter?
A) Smooth starting of the motor
B) High starting torque with low current
C) Simple design and low cost
D) Reduces full-load current
Rationale: DOL starters are simple and inexpensive, though they draw high starting current.
7. A reversing motor starter allows:
A) Multiple motors to run simultaneously
B) Voltage regulation
C) Changing motor direction
D) Speed control
Rationale: Reversing starters swap two of the three phases to reverse rotation direction.
8. Which of the following is NOT part of a typical motor starter?
A) Contactor
B) Overload relay
C) Fuse or circuit breaker
D) Capacitor bank
Rationale: Capacitors are not standard in starters unless it’s a single-phase motor needing phase
shift.
PRACTICE EXAM QUESTIONS WITH ANSWERS AND
RATIONALES
Section A: Motor Theory & Safety
1. Which of the following is the most common type of motor used in industrial
applications?
A) Single-phase AC motor
B) Three-phase AC motor
C) DC series motor
D) Stepper motor
Rationale: Three-phase AC motors are preferred in industry for efficiency and torque
consistency.
2. What is the main purpose of a motor overload relay?
A) To start the motor
B) To protect the motor from overheating
C) To reverse motor direction
D) To regulate voltage
Rationale: Overload relays detect excessive current that can overheat the motor and interrupt the
circuit.
3. Before performing maintenance on a motor control system, the first step is:
A) Wear gloves
B) Turn off the motor
C) Lockout/tagout the circuit
D) Test the motor with a multimeter
Rationale: Lockout/tagout ensures that the circuit cannot be energized accidentally, protecting
personnel.
4. A bimetallic overload relay works by:
A) Using magnetic fields to detect current
B) Expanding metal strips that bend with heat caused by excess current
C) Using a timer relay to delay trips
D) Sensing voltage drop across windings
, Rationale: Bimetallic strips bend with heat to mechanically open the contact when the current is
too high.
5. Which type of switch is often used for emergency motor shutdown?
A) Selector switch
B) Push button (Start)
C) Push button (Stop/E-Stop)
D) Limit switch
Rationale: Stop or emergency-stop buttons are designed for quick and safe motor shutdown.
Section B: Motor Starters & Control Devices
6. What is the main advantage of a direct-on-line (DOL) starter?
A) Smooth starting of the motor
B) High starting torque with low current
C) Simple design and low cost
D) Reduces full-load current
Rationale: DOL starters are simple and inexpensive, though they draw high starting current.
7. A reversing motor starter allows:
A) Multiple motors to run simultaneously
B) Voltage regulation
C) Changing motor direction
D) Speed control
Rationale: Reversing starters swap two of the three phases to reverse rotation direction.
8. Which of the following is NOT part of a typical motor starter?
A) Contactor
B) Overload relay
C) Fuse or circuit breaker
D) Capacitor bank
Rationale: Capacitors are not standard in starters unless it’s a single-phase motor needing phase
shift.
