BOC Electrical Systems Efficiency &
Controls Module Exam Practice
Questions And Correct Answers
(Verified Answers) Plus Rationales 2026
Q&A | Instant Download Pdf
1. Which measure most directly improves electrical system efficiency in
commercial buildings?
A. Increasing breaker sizes
B. Reducing power factor
C. Power factor correction
D. Adding more transformers
Answer: C
Power factor correction reduces reactive power demand, improving
overall system efficiency and reducing losses in electrical distribution.
2. What is the primary function of a variable frequency drive (VFD)?
A. Convert AC to DC only
B. Control motor speed by varying frequency and voltage
, C. Increase motor torque permanently
D. Eliminate harmonics completely
Answer: B
A VFD controls motor speed and torque by adjusting the supply
frequency and voltage, improving energy efficiency in motor-driven
systems.
3. In electrical systems, low power factor typically results in:
A. Reduced current draw
B. Increased system efficiency
C. Higher line losses and demand charges
D. Lower voltage levels at source only
Answer: C
Low power factor increases current draw for the same useful power,
leading to higher I²R losses and utility penalties.
4. Which device is commonly used to correct lagging power factor?
A. Inductors
B. Capacitors
C. Transformers
D. Resistors
Answer: B
Capacitors supply reactive power locally, offsetting inductive loads
and improving power factor.
,5. Which control system is most commonly used for centralized building
energy management?
A. PLC only
B. BAS (Building Automation System)
C. Manual relay panels
D. Analog timers
Answer: B
A BAS integrates and automates HVAC, lighting, and electrical
systems for optimized energy performance.
6. Harmonic distortion in electrical systems is primarily caused by:
A. Resistive loads
B. Linear inductive loads only
C. Non-linear loads such as VFDs and computers
D. Overhead transmission lines
Answer: C
Non-linear loads draw current in non-sinusoidal waveforms,
introducing harmonic distortion into the system.
7. The main purpose of demand response programs is to:
A. Increase peak energy consumption
B. Reduce electricity usage during peak periods
C. Eliminate reactive power
D. Increase transformer losses
Answer: B
, Demand response reduces load during peak grid demand, improving
system stability and reducing energy costs.
8. Which lighting technology is generally most energy efficient?
A. Incandescent
B. Halogen
C. LED
D. Fluorescent T12
Answer: C
LED lighting provides the highest efficacy and longest lifespan among
common lighting technologies.
9. Electrical energy consumption is measured in:
A. Volts
B. Watts
C. Kilowatt-hours
D. Amperes
Answer: C
Kilowatt-hours represent the total energy used over time, combining
power and duration of usage.
10. What does a current transformer (CT) primarily do?
A. Increase voltage
B. Measure high current by scaling it down
C. Store electrical energy
D. Filter harmonics
Controls Module Exam Practice
Questions And Correct Answers
(Verified Answers) Plus Rationales 2026
Q&A | Instant Download Pdf
1. Which measure most directly improves electrical system efficiency in
commercial buildings?
A. Increasing breaker sizes
B. Reducing power factor
C. Power factor correction
D. Adding more transformers
Answer: C
Power factor correction reduces reactive power demand, improving
overall system efficiency and reducing losses in electrical distribution.
2. What is the primary function of a variable frequency drive (VFD)?
A. Convert AC to DC only
B. Control motor speed by varying frequency and voltage
, C. Increase motor torque permanently
D. Eliminate harmonics completely
Answer: B
A VFD controls motor speed and torque by adjusting the supply
frequency and voltage, improving energy efficiency in motor-driven
systems.
3. In electrical systems, low power factor typically results in:
A. Reduced current draw
B. Increased system efficiency
C. Higher line losses and demand charges
D. Lower voltage levels at source only
Answer: C
Low power factor increases current draw for the same useful power,
leading to higher I²R losses and utility penalties.
4. Which device is commonly used to correct lagging power factor?
A. Inductors
B. Capacitors
C. Transformers
D. Resistors
Answer: B
Capacitors supply reactive power locally, offsetting inductive loads
and improving power factor.
,5. Which control system is most commonly used for centralized building
energy management?
A. PLC only
B. BAS (Building Automation System)
C. Manual relay panels
D. Analog timers
Answer: B
A BAS integrates and automates HVAC, lighting, and electrical
systems for optimized energy performance.
6. Harmonic distortion in electrical systems is primarily caused by:
A. Resistive loads
B. Linear inductive loads only
C. Non-linear loads such as VFDs and computers
D. Overhead transmission lines
Answer: C
Non-linear loads draw current in non-sinusoidal waveforms,
introducing harmonic distortion into the system.
7. The main purpose of demand response programs is to:
A. Increase peak energy consumption
B. Reduce electricity usage during peak periods
C. Eliminate reactive power
D. Increase transformer losses
Answer: B
, Demand response reduces load during peak grid demand, improving
system stability and reducing energy costs.
8. Which lighting technology is generally most energy efficient?
A. Incandescent
B. Halogen
C. LED
D. Fluorescent T12
Answer: C
LED lighting provides the highest efficacy and longest lifespan among
common lighting technologies.
9. Electrical energy consumption is measured in:
A. Volts
B. Watts
C. Kilowatt-hours
D. Amperes
Answer: C
Kilowatt-hours represent the total energy used over time, combining
power and duration of usage.
10. What does a current transformer (CT) primarily do?
A. Increase voltage
B. Measure high current by scaling it down
C. Store electrical energy
D. Filter harmonics
