Electricity Level 4 Section 7 Questions
and Answers | Latest Version | 2024/2025
| Correct & Verified
What is the primary purpose of a programmable logic controller (PLC) in electrical systems?
✔✔ A PLC is used to automate control processes in industrial applications, replacing traditional
relay-based systems.
How does a variable frequency drive (VFD) control motor speed?
✔✔ A VFD adjusts the frequency and voltage of the power supplied to the motor, allowing
precise speed and torque control.
What is the significance of reactive power in an AC electrical system?
✔✔ Reactive power is necessary for maintaining the voltage levels required to power magnetic
components like transformers and motors.
What is the purpose of a load calculation in electrical design?
✔✔ Load calculations determine the total electrical demand of a system to ensure proper sizing
of conductors, breakers, and transformers.
1
, Why is harmonics mitigation important in electrical systems?
✔✔ Harmonics mitigation reduces distortions in the power waveform, improving power quality
and preventing overheating of equipment.
What is a common use for fiber optic cables in electrical systems?
✔✔ Fiber optic cables are used for high-speed data communication and signal transmission with
minimal interference.
How does a three-phase motor differ from a single-phase motor?
✔✔ A three-phase motor is more efficient, provides constant torque, and is used in industrial
applications, while a single-phase motor is suitable for smaller loads.
What is the role of a current transformer (CT) in power monitoring?
✔✔ A current transformer steps down high current levels to a measurable value for monitoring
and protection purposes.
Why are synchronous motors used in specific applications?
✔✔ Synchronous motors provide precise speed control and can improve power factor in
electrical systems.
2
and Answers | Latest Version | 2024/2025
| Correct & Verified
What is the primary purpose of a programmable logic controller (PLC) in electrical systems?
✔✔ A PLC is used to automate control processes in industrial applications, replacing traditional
relay-based systems.
How does a variable frequency drive (VFD) control motor speed?
✔✔ A VFD adjusts the frequency and voltage of the power supplied to the motor, allowing
precise speed and torque control.
What is the significance of reactive power in an AC electrical system?
✔✔ Reactive power is necessary for maintaining the voltage levels required to power magnetic
components like transformers and motors.
What is the purpose of a load calculation in electrical design?
✔✔ Load calculations determine the total electrical demand of a system to ensure proper sizing
of conductors, breakers, and transformers.
1
, Why is harmonics mitigation important in electrical systems?
✔✔ Harmonics mitigation reduces distortions in the power waveform, improving power quality
and preventing overheating of equipment.
What is a common use for fiber optic cables in electrical systems?
✔✔ Fiber optic cables are used for high-speed data communication and signal transmission with
minimal interference.
How does a three-phase motor differ from a single-phase motor?
✔✔ A three-phase motor is more efficient, provides constant torque, and is used in industrial
applications, while a single-phase motor is suitable for smaller loads.
What is the role of a current transformer (CT) in power monitoring?
✔✔ A current transformer steps down high current levels to a measurable value for monitoring
and protection purposes.
Why are synchronous motors used in specific applications?
✔✔ Synchronous motors provide precise speed control and can improve power factor in
electrical systems.
2
