Transmission and Distribution Systems MCQs (Part-14)
What is the main function of a transmission line?
A Power transfer
B Voltage control
C Load balancing
D Power regulation
The primary function of transmission lines is to transfer electrical power from generation plants to substations. These lines carry high‐voltage electricity over long distances, enabling efficient power distribution to consumers.
What is the typical voltage range for medium voltage distribution systems?
A 230 V
B 110 kV
C 11 kV
D 400 V
Medium voltage distribution systems typically operate around 11 kV. This voltage is suitable for transferring power over relatively short distances, from substations to homes and businesses, before it is stepped down for use.
What type of conductor is most commonly used for overhead transmission lines?
A Steel
B Aluminum
C Iron
D Copper
Aluminum is widely used in overhead transmission lines due to its lightweight, good conductivity, and lower cost. Its properties make it ideal for long‐distance transmission, where weight and efficiency are critical factors.
What does a step‐down transformer do in a power system?
A Regulate frequency
B Decrease current
C Increase voltage
D Decrease voltage
A step‐down transformer reduces the high voltage from transmission lines to a lower, usable voltage. This ensures the voltage is suitable for local distribution to homes and businesses, maintaining safety and efficiency.
What is the primary purpose of insulators in overhead transmission lines?
A Support conductors
B Reduce sag
C Voltage regulation
D Protect against faults
Insulators support transmission line conductors and prevent them from coming into contact with other structures or the ground. They also provide electrical insulation, ensuring safe operation by preventing short circuits or faults.
What is the primary cause of power loss in transmission lines?
A Poorearthing
B High resistance
C High voltage
D Insulation breakdown
Power loss in transmission lines is caused primarily by resistance in the conductors, which converts electrical energy into heat. This results in energy loss, especially over long distances, making it important to use conductors with low resistance.
How does voltage regulation improve power system efficiency?
A Increases load
B Increases power factor
C Maintains consistent voltage
D Reduces current
Voltage regulation ensures that voltage remains within acceptable levels, even with varying loads. By maintaining a consistent voltage, it prevents equipment damage and enhances the overall efficiency of the power system, reducing losses and improving reliability.
What is the purpose of a substation in power distribution?
A Step‐up voltage
B Control current
C Step‐down voltage
D Store power
A substation’s primary function is to step down high transmission voltage to lower levels suitable for distribution to consumers. This ensures that the voltage is safe and usable for residential and commercial applications.
What is the impact of using underground cables in power distribution?
A Increased losses
B Reduced voltage
C Higher cost
D Increased efficiency
Underground cables are more expensive to install and maintain than overhead lines. However, they are less vulnerable to environmental damage, offering a safer, more reliable solution, especially in urban areas where aesthetics and safety are priorities.
What is the role of earthing in electrical systems?
A Prevent electric shock
B Control reactive power
C Protect from overload
D Improve insulation
Earthing provides a safe path for fault currents to flow into the ground. This minimizes the risk of electric shock and ensures safety by directing excess electrical energy away from users and equipment during fault conditions.
How does a fault current analysis aid in system protection?
A Optimizes energy storage
B Identifies protection device settings
C Determines voltage regulation
D Prevents grid integration
Fault current analysis helps determine the magnitude of fault currents in a system. This information is crucial for selecting and setting the correct protection devices, such as circuit breakers, to prevent damage during fault conditions.
What does a protection relay do in a power system?
A Control voltage
B Detect faults
C Improve efficiency
D Increase power flow
Protection relays monitor the system for fault conditions, such as short circuits or overloads. When a fault is detected, the relay sends a signal to disconnect the faulty section, preventing further damage and maintaining system stability.
What is grid integration of renewable energy?
A Storing energy
B Power generation
C Combining energy sources
D Power distribution
Grid integration of renewable energy involves connecting renewable energy sources, such as wind or solar, to the main power grid. This allows for the sharing of clean energy and helps balance supply and demand by leveraging diverse energy sources.
What is the primary advantage of using smart meters in electrical systems?
A Reduced power consumption
B Increased energy production
C Reduced voltage
D Accurate energy billing
Smart meters provide real‐time data on energy usage, enabling accurate billing and helping both consumers and utilities monitor consumption patterns. They also enable dynamic pricing, which can improve grid efficiency and encourage energy conservation.
What is the main benefit of using microgrids in power systems?
A Independent operation
B Increased voltage
C Increased frequency
D Reduced current
Microgrids can operate independently from the main grid, providing a localized power supply. They often use renewable energy sources and can enhance energy security, especially during grid outages, by offering reliable power to communities or critical infrastructure.