What is the typical voltage range for medium voltage systems?
A 0-1 kV
B 1-33 kV
C 33-110 kV
D Above 110 kV
Medium voltage systems typically operate between 1 kV and 33 kV and are used for industrial and commercial power distribution.
Which type of insulator is commonly used for low-voltage distribution lines?
A Pin insulator
B Suspension insulator
C Strain insulator
D Shackle insulator
Shackle insulators are used in low-voltage distribution systems because they are compact, easy to install, and cost-effective.
What is the purpose of a line trap in a power transmission system?
A To improve power factor
B To filter out high-frequency communication signals
C To protect the system from overvoltage
D To regulate voltage
Line traps are used to block high-frequency signals that are used in power line communication systems, preventing them from entering undesired sections of the transmission network.
What type of fault occurs when a conductor comes into contact with the ground?
A Line-to-line fault
B Double line-to-ground fault
C Line-to-ground fault
D Three-phase fault
A line-to-ground fault occurs when one conductor comes into contact with the ground or a grounded object, leading to current flow through the earth.
What is the term for the distance between a conductor and the supporting structure?
A Clearance
B Span
C Sag
D Tension
Clearance is the distance between the conductor and the supporting structure or ground, ensuring safety and preventing accidental contact.
What is the primary function of a distribution transformer?
A To step up voltage
B To reduce transmission losses
C To step down voltage for end users
D To increase power factor
Distribution transformers step down the high transmission voltage to lower voltages suitable for use by consumers, either residential or industrial.
What is the unit of transmission line capacitance?
A Ohm
B Henry
C Farad
D Ampere
Capacitance is measured in farads and refers to the ability of a transmission line to store electrical energy in an electric field.
What is the main advantage of using underground cables over overhead lines?
A Lower cost
B Better protection from environmental factors
C Higher power capacity
D Easier maintenance
Underground cables are less exposed to environmental hazards like wind, lightning, and falling trees, making them more reliable than overhead lines.
What is the primary purpose of load balancing in a power system?
A To increase voltage levels
B To evenly distribute electrical load across the system
C To reduce conductor size
D To eliminate reactive power
Load balancing ensures that power is evenly distributed across the system, preventing overloading of specific components and enhancing overall system efficiency.
What is the typical range of voltage for high-voltage transmission lines?
A 11-33 kV
B 33-110 kV
C 110-765 kV
D Above 765 kV
High-voltage transmission lines typically operate between 110 kV and 765 kV, facilitating the efficient transmission of electricity over long distances with minimal losses.
What is the purpose of using dampers on overhead transmission lines?
A To reduce sag
B To minimize wind-induced vibrations
C To increase conductivity
D To prevent corona discharge
Dampers are used to minimize the mechanical vibrations induced by wind or other environmental conditions, preventing conductor damage or wear.
Which type of relay is commonly used for overcurrent protection in distribution systems?
A Distance relay
B Overcurrent relay
C Differential relay
D Buchholz relay
Overcurrent relays are used in distribution systems to detect excessive current flow and disconnect the faulty section to prevent damage to the equipment.
What is the purpose of a ground wire in transmission lines?
A To carry load current
B To protect the system from lightning strikes
C To reduce sag
D To regulate voltage
Ground wires are used to provide a safe path for lightning surges to be conducted away from the power lines and to protect the transmission system from damage caused by lightning strikes.
What is the main factor affecting corona discharge?
A Conductor size
B Voltage level
C Air pressure
D Humidity
Corona discharge is significantly affected by the voltage level and the electric field intensity around conductors. Higher voltage levels increase the likelihood of corona discharge.
Which parameter increases in a transmission line when its length increases?
A Voltage
B Resistance
C Frequency
D Power factor
As the length of a transmission line increases, its resistance increases, leading to higher power losses and reduced efficiency in power delivery.
What is the purpose of using oil in transformers?
A To reduce magnetic losses
B To insulate and cool the transformer
C To increase efficiency
D To regulate voltage
Oil in transformers provides both insulation between windings and cooling to dissipate heat generated during the transformation of electrical energy.
What is the term for the vertical distance between an overhead conductor and the ground?
A Clearance
B Sag
C Tension
D Span
Sag is the vertical distance between the conductor’s lowest point and the ground or a reference point, influenced by temperature, conductor weight, and environmental conditions.
What is the main disadvantage of overhead lines compared to underground cables?
A Higher installation cost
B Vulnerability to environmental factors
C More difficult to maintain
D Higher transmission losses
Overhead lines are more exposed to environmental hazards such as storms, lightning, and falling trees, making them more vulnerable compared to underground cables.
Which type of fault occurs most frequently in power systems?
A Three-phase fault
B Line-to-line fault
C Line-to-ground fault
D Double line-to-ground fault
Line-to-ground faults occur most frequently because they involve one conductor coming into contact with the ground or a grounded object, which is relatively common in power systems.
What is the main advantage of smart meters in distribution systems?
A Higher voltage levels
B Accurate energy measurement and monitoring
C Reduced transmission losses
D Increased load capacity
Smart meters provide real-time data on energy consumption, allowing better energy management, accurate billing, and improved operational efficiency in distribution systems.
What is the primary purpose of transmission lines in a power system?
A To distribute power locally
B To transmit power over long distances
C To generate power
D To store power
Transmission lines are used to carry electrical power from generation plants to substations over long distances with minimal losses.
What type of conductor is commonly used for high-voltage transmission lines?
A Aluminum Conductor Steel Reinforced (ACSR)
B Twisted pair cables
C Coaxial cables
D Fiber optic cables
ACSR conductors are used for high-voltage transmission lines due to their high tensile strength and good conductivity.
Which device is used to prevent voltage fluctuations in a distribution system?
A Transformer
B Voltage regulator
C Circuit breaker
D Capacitor bank
Voltage regulators maintain a constant output voltage despite variations in load or input voltage.
What is the purpose of a transmission line’s shield wire?
A To transmit power
B To protect against lightning strikes
C To improve efficiency
D To reduce sag
Shield wires (ground wires) provide a path for lightning strikes to safely flow to the ground, protecting the conductors.
Why are transmission lines installed at a height from the ground?