Transmission and Distribution Systems MCQs (Part-10)
What is the primary purpose of line impedance in a transmission line?
A To regulate voltage
B To resist the flow of current and control power transfer
C To step up voltage
D To reduce capacitance
Line impedance, comprising resistance and reactance, governs how current flows through the line, affecting power transfer and voltage regulation.
What is the effect of inductance in a transmission line?
A Increases line resistance
B Opposes changes in current
C Reduces voltage drop
D Improves power factor
Inductance opposes rapid changes in current due to the magnetic field created around the conductor, affecting system stability.
How does capacitance affect a transmission line?
A Increases power losses
B Causes voltage rise at light loads
C Reduces conductor resistance
D Eliminates inductance
Capacitance causes the Ferranti effect, where the receiving-end voltage becomes higher than the sending-end voltage under low load conditions.
What is corona discharge?
A A fault in the conductor
B The ionization of air around high-voltage conductors
C A type of short circuit
D An insulation failure
Corona discharge occurs when the electric field strength around a conductor exceeds the breakdown strength of air, causing energy loss and ionization of air.
Which factor increases corona loss?
A Decreasing voltage
B Increasing conductor size
C Decreasing atmospheric pressure
D Increasing conductor spacing
Lower atmospheric pressure reduces the breakdown strength of air, increasing the likelihood of corona discharge.
What is the primary purpose of sag in a transmission line?
A To improve power quality
B To allow for thermal expansion and contraction of the conductor
C To reduce inductive reactance
D To stabilize capacitance
Sag allows conductors to expand and contract with temperature changes, ensuring mechanical stability and preventing excessive tension.
What is the impact of excessive sag in a transmission line?
A Increases line resistance
B Decreases ground clearance
C Reduces capacitance
D Increases voltage
Excessive sag reduces the clearance between the conductor and the ground, increasing the risk of accidents and reducing safety.
What is earthing’s primary role in a power system?
A To increase capacitance
B To provide a safe path for fault currents to the ground
C To reduce inductance
D To stabilize frequency
Earthing ensures safety by directing fault currents into the ground, preventing hazardous voltages from causing damage to equipment and personnel.
What is the purpose of fault current analysis in power systems?
A To measure voltage stability
B To determine the magnitude and location of faults
C To reduce conductor resistance
D To increase capacitance
Fault current analysis identifies the magnitude and location of faults, which helps in designing protection systems to isolate faults and protect equipment.
Which protection device detects faults and triggers a circuit breaker?
A Capacitor
B Relay
C Lightning arrester
D Transformer
Relays monitor the power system for faults and abnormal conditions, signaling circuit breakers to disconnect faulty sections and prevent damage.
What is grid integration in power systems?
A Combining multiple loads in a grid
B Connecting renewable energy sources to the power grid
C Isolating renewable energy sources from the grid
D Increasing voltage levels
Grid integration involves connecting renewable energy sources like solar and wind to the main power grid, ensuring reliable energy distribution.
What is the role of a smart meter in a distribution system?
A To step up voltage levels
B To measure energy usage and provide real-time data
C To reduce power losses
D To improve line capacitance
Smart meters provide real-time data on energy consumption, allowing for accurate billing, demand-side management, and improved energy efficiency.
What is Advanced Metering Infrastructure (AMI)?
A A system for manual meter reading
B A technology for remote monitoring and control of energy usage
C A type of energy storage system
D A transformer control mechanism
AMI integrates smart meters and communication systems, enabling remote monitoring, energy management, and efficient billing processes.
What is a microgrid?
A A power grid for long-distance transmission
B A localized energy system that can operate independently or with the main grid
C A control system for transformers
D A device for voltage regulation
Microgrids are small-scale power systems that can function independently or be connected to the larger grid, providing localized energy solutions.
What is the primary cause of reactive power in a power system?
A Inductive and capacitive loads
B Inductive and capacitive loads
C Resistance of conductors
D Low system voltage
Reactive power is required by inductive and capacitive loads to create and sustain electric and magnetic fields, helping in the operation of motors, transformers, etc.
How does capacitance affect high-voltage, long-distance transmission lines?
A Increases line resistance
B Leads to Ferranti effect under light loads
C Reduces power losses
D Eliminates voltage fluctuations
Capacitance in long-distance transmission lines causes a voltage rise at the receiving end under light load conditions, known as the Ferranti effect.
What is the primary purpose of a lightning arrester?
A To reduce line impedance
B To protect the system from overvoltage due to lightning
C To step down voltage levels
D To store energy
Lightning arresters are used to protect the power system from lightning-induced surges by directing the high-voltage surge safely to the ground.
What is the main advantage of microgrids?
A They reduce power factor
B They improve energy reliability and integrate renewables
C They increase line losses
D They eliminate voltage fluctuations
Microgrids enhance the reliability of local power supplies and allow for efficient integration of renewable energy sources, such as solar and wind.
What is the primary cause of reactive power in a power system?
A Inductive and capacitive loads
B Inductive and capacitive loads
C Resistance of conductors
D Low system voltage
Reactive power is required by inductive and capacitive loads, like motors and transformers, to create and sustain electric and magnetic fields.
What is the purpose of reactive power compensation in a transmission system?
A To increase active power
B To stabilize voltage levels and improve power factor
C To reduce system losses
D To increase system frequency
Reactive power compensation ensures that voltage levels are maintained within acceptable limits and improves the overall power factor, making the system more efficient.