ALBERTA ELECTRICIAN FOURTH PERIOD AIT EXAM –COMPLETE
200 PRACTICE QUESTIONS WITH VERIFIED ANSWERS AND
RATIONALES
TABLE OF CONTENTS
Section Domain Approx. Page
Questions Reference
Section Machines 34 Page 1
1
Section Control and Switching / PLC 40 Page 6
2
Section Fire Alarm Systems & Red Seal 26 Page 12
3 Program & Industry Network
Section Applications of Electronics 36 Page 16
4
Section Canadian Electrical Code Part 64 Page 22
5 1 / Applications and Safety
SECTION 1: MACHINES
(Questions 1–34)
1. Which of the following describes the primary function of a
commutator in a DC machine?
A. To convert DC to AC internally
B. To mechanically rectify the AC induced in the armature
C. To provide a rotating magnetic field
,D. To reduce eddy currents in the core
B. To mechanically rectify the AC induced in the armature
Rationale: The commutator reverses the connection of the armature
coils to the external circuit at the precise moment the current reverses,
producing a unidirectional DC output.
2. In a three-phase alternator, what is the relationship between
mechanical speed and electrical frequency?
A. Frequency is independent of rotor speed
B. Frequency is directly proportional to rotor speed and number of
poles
C. Frequency is inversely proportional to the number of poles
D. Frequency is only determined by excitation voltage
B. Frequency is directly proportional to rotor speed and number of
poles
Rationale: Frequency is determined by f = (P × N) / 120, so it is directly
proportional to both rotor speed and number of poles.
3. A single-phase transformer has 500 primary turns and 100
secondary turns. If the primary is connected to 120V AC, what is the
secondary voltage?
A. 600 V
B. 24 V
C. 120 V
D. 12 V
B. 24 V
Rationale: Turns ratio is 500/100 = 5. Secondary voltage = 120/5 = 24V.
4. What is the primary purpose of a current transformer in a metering
circuit?
,A. To step up voltage for metering
B. To provide a low-current, isolated signal proportional to primary
current
C. To protect the meter from voltage surges
D. To measure power factor directly
B. To provide a low-current, isolated signal proportional to primary
current
Rationale: CTs step down high currents to a safe level (typically 5A or
1A) for metering and protection while providing electrical isolation.
5. Which single-phase motor requires a capacitor in its auxiliary
winding to create a phase shift for starting?
A. Shaded-pole motor
B. Split-phase motor
C. Capacitor-start motor
D. Repulsion motor
C. Capacitor-start motor
Rationale: A capacitor-start motor uses a capacitor in series with the
start winding to create a large phase angle, producing high starting
torque.
6. In a DC motor, what is the effect of increasing field current while
keeping armature voltage constant?
A. Motor speed increases
B. Motor speed decreases
C. Motor torque decreases
D. Motor speed remains unchanged
B. Motor speed decreases
Rationale: Increasing field current increases magnetic flux. Since N ∝ (V
− IaRa)/Φ, an increase in flux decreases motor speed.
, 7. What is the primary difference between a power transformer and a
distribution transformer?
A. Power transformers are only used in substations
B. Distribution transformers are designed for higher voltage ratings
C. Power transformers are typically larger and designed for higher
power ratings
D. Distribution transformers have higher efficiency at full load
C. Power transformers are typically larger and designed for higher
power ratings
Rationale: Power transformers handle transmission-level voltages and
power, while distribution transformers step down voltage for local use
and are generally smaller.
8. A three-phase motor is connected in Delta. The line voltage is 480V.
What is the voltage across each motor winding?
A. 277 V
B. 480 V
C. 831 V
D. 240 V
B. 480 V
Rationale: In a Delta connection, phase voltage equals line voltage, so
each winding sees 480V.
9. Which of the following is a symptom of a shorted turn in a
transformer winding?
A. Increased secondary voltage
B. Excessive heating and decreased secondary voltage
C. No change in operation
D. Increased insulation resistance
B. Excessive heating and decreased secondary voltage
200 PRACTICE QUESTIONS WITH VERIFIED ANSWERS AND
RATIONALES
TABLE OF CONTENTS
Section Domain Approx. Page
Questions Reference
Section Machines 34 Page 1
1
Section Control and Switching / PLC 40 Page 6
2
Section Fire Alarm Systems & Red Seal 26 Page 12
3 Program & Industry Network
Section Applications of Electronics 36 Page 16
4
Section Canadian Electrical Code Part 64 Page 22
5 1 / Applications and Safety
SECTION 1: MACHINES
(Questions 1–34)
1. Which of the following describes the primary function of a
commutator in a DC machine?
A. To convert DC to AC internally
B. To mechanically rectify the AC induced in the armature
C. To provide a rotating magnetic field
,D. To reduce eddy currents in the core
B. To mechanically rectify the AC induced in the armature
Rationale: The commutator reverses the connection of the armature
coils to the external circuit at the precise moment the current reverses,
producing a unidirectional DC output.
2. In a three-phase alternator, what is the relationship between
mechanical speed and electrical frequency?
A. Frequency is independent of rotor speed
B. Frequency is directly proportional to rotor speed and number of
poles
C. Frequency is inversely proportional to the number of poles
D. Frequency is only determined by excitation voltage
B. Frequency is directly proportional to rotor speed and number of
poles
Rationale: Frequency is determined by f = (P × N) / 120, so it is directly
proportional to both rotor speed and number of poles.
3. A single-phase transformer has 500 primary turns and 100
secondary turns. If the primary is connected to 120V AC, what is the
secondary voltage?
A. 600 V
B. 24 V
C. 120 V
D. 12 V
B. 24 V
Rationale: Turns ratio is 500/100 = 5. Secondary voltage = 120/5 = 24V.
4. What is the primary purpose of a current transformer in a metering
circuit?
,A. To step up voltage for metering
B. To provide a low-current, isolated signal proportional to primary
current
C. To protect the meter from voltage surges
D. To measure power factor directly
B. To provide a low-current, isolated signal proportional to primary
current
Rationale: CTs step down high currents to a safe level (typically 5A or
1A) for metering and protection while providing electrical isolation.
5. Which single-phase motor requires a capacitor in its auxiliary
winding to create a phase shift for starting?
A. Shaded-pole motor
B. Split-phase motor
C. Capacitor-start motor
D. Repulsion motor
C. Capacitor-start motor
Rationale: A capacitor-start motor uses a capacitor in series with the
start winding to create a large phase angle, producing high starting
torque.
6. In a DC motor, what is the effect of increasing field current while
keeping armature voltage constant?
A. Motor speed increases
B. Motor speed decreases
C. Motor torque decreases
D. Motor speed remains unchanged
B. Motor speed decreases
Rationale: Increasing field current increases magnetic flux. Since N ∝ (V
− IaRa)/Φ, an increase in flux decreases motor speed.
, 7. What is the primary difference between a power transformer and a
distribution transformer?
A. Power transformers are only used in substations
B. Distribution transformers are designed for higher voltage ratings
C. Power transformers are typically larger and designed for higher
power ratings
D. Distribution transformers have higher efficiency at full load
C. Power transformers are typically larger and designed for higher
power ratings
Rationale: Power transformers handle transmission-level voltages and
power, while distribution transformers step down voltage for local use
and are generally smaller.
8. A three-phase motor is connected in Delta. The line voltage is 480V.
What is the voltage across each motor winding?
A. 277 V
B. 480 V
C. 831 V
D. 240 V
B. 480 V
Rationale: In a Delta connection, phase voltage equals line voltage, so
each winding sees 480V.
9. Which of the following is a symptom of a shorted turn in a
transformer winding?
A. Increased secondary voltage
B. Excessive heating and decreased secondary voltage
C. No change in operation
D. Increased insulation resistance
B. Excessive heating and decreased secondary voltage
