Transmission and Distribution Systems MCQs (Part-7)
What is the primary role of a transmission system in a power network?
A To generate power
B To distribute power locally
C To transmit power over long distances
D To step down voltage levels
The transmission system is responsible for carrying electricity over long distances from power plants to substations, reducing losses during the journey.
Which property of a conductor minimizes power loss in a transmission line?
A High resistance
B High conductivity
C High tensile strength
D High weight
Conductors with high conductivity reduce resistive losses, improving efficiency in power transmission.
What type of transformer is installed in substations for voltage regulation?
A Step-up transformer
B Step-down transformer
C Tap-changing transformer
D Auto-transformer
Tap-changing transformers allow for voltage regulation by adjusting the turns ratio of the transformer, maintaining stable output voltage.
What is the purpose of neutral grounding in a power system?
A To step up voltage
B To improve power factor
C To provide a path for fault currents
D To reduce current
Neutral grounding ensures safety by providing a controlled path for fault currents to return to the ground, protecting equipment and personnel.
What is the significance of power factor in a power system?
A It indicates the frequency stability
B It measures the efficiency of power usage
C It determines the voltage regulation
D It calculates the current capacity
Power factor is the ratio of active power to apparent power, indicating how effectively electrical power is being used in the system.
Which component is responsible for protecting a power system from short circuits?
A Capacitor
B Circuit breaker
C Transformer
D Lightning arrester
Circuit breakers detect and disconnect the faulty sections of a power system during short circuits, preventing equipment damage.
What is the main advantage of high-voltage transmission?
A Higher conductor resistance
B Reduced transmission losses
C Increased power factor
D Lower system frequency
High voltage transmission reduces current, which minimizes power losses in the transmission lines due to resistance.
Which type of insulator is commonly used in distribution systems with sharp bends or terminations?
A Suspension insulator
B Strain insulator
C Pin insulator
D Shackle insulator
Strain insulators are used in areas of high tension, such as at bends and terminations in the transmission and distribution systems.
What is the purpose of a substation transformer?
A To step up or step down voltage levels
B To generate electrical power
C To store energy
D To increase system frequency
Substation transformers adjust the voltage levels to appropriate levels for transmission or distribution.
What is reactive power used for in a power system?
A To perform useful work
B To establish magnetic fields in inductive loads
C To reduce power losses
D To increase active power
Reactive power helps to create the magnetic fields required for the operation of inductive devices like motors and transformers.
What is the function of a voltage regulator in a distribution network?
A To increase current flow
B To maintain constant voltage levels
C To step up voltage
D To protect against short circuits
Voltage regulators ensure stable voltage levels across the distribution network, preventing fluctuations that could damage equipment or affect performance.
Which type of conductor arrangement reduces skin effect?
A Solid conductor
B Stranded conductor
C Twisted pair
D Coaxial cable
Stranded conductors distribute the current more uniformly across the conductor’s surface, minimizing the impact of the skin effect at higher frequencies.
What is the typical frequency of AC power in most countries?
A 30 Hz
B 50 Hz
C 75 Hz
D 90 Hz
Most countries use 50 Hz as the standard frequency for AC power, though some, like the United States, use 60 Hz.
What is the purpose of earthing in a substation?
A To increase voltage levels
B To provide a path for fault currents
C To reduce conductor resistance
D To increase system efficiency
Earthing provides a safe route for fault currents to return to the ground, protecting both people and equipment from electrical hazards.
What is the primary advantage of using high-voltage transmission for long distances?
A Higher conductor resistance
B Reduced transmission losses
C Increased power factor
D Lower system frequency
High-voltage transmission reduces current for the same amount of power, minimizing I²R losses in the transmission lines.
Which type of insulator is commonly used in distribution systems with sharp bends or terminations?
A Suspension insulator
B Strain insulator
C Pin insulator
D Shackle insulator
Strain insulators are used in high-tension areas, such as sharp bends or terminations, to handle mechanical stress.
What is the purpose of a substation transformer?
A To step up or step down voltage levels
B To generate electrical power
C To store energy
D To increase system frequency
Substation transformers adjust voltage levels either by stepping up or stepping down to ensure power reaches consumers at safe and usable levels.
What is reactive power used for in a power system?
A To perform useful work
B To establish magnetic fields in inductive loads
C To reduce power losses
D To increase active power
Reactive power is necessary to create magnetic fields required for the operation of devices like transformers and motors.
What is the function of a capacitor bank in a power distribution system?
A To reduce voltage levels
B To improve power factor by providing reactive power
C To increase current flow
D To reduce insulation requirements
Capacitor banks provide leading reactive power, helping to correct power factor and improve system efficiency.
What is the primary advantage of underground cables over overhead lines?
A Lower cost
B Better protection from environmental factors
C Higher current-carrying capacity
D Easier maintenance
Underground cables are protected from weather conditions like storms, lightning, and falling trees, ensuring greater reliability.