Transmission and Distribution Systems MCQs (Part-9)
What is the primary goal of energy efficiency in electrical systems?
A Increase voltage
B Reduce losses
C Control power
D Improve insulation
The primary goal of energy efficiency in electrical systems is to reduce losses during power transmission and distribution. This involves minimizing energy wastage through methods like high‐voltage transmission, proper insulation, and using efficient transformers.
What is reactive power used for in a power system?
A Increase power flow
B Reduce losses
C Maintain voltage
D Stabilize frequency
Reactive power does not perform useful work but is essential for maintaining voltage levels in a power system. It helps to balance the system and ensure proper functioning of devices such as motors and transformers by supporting the electric fields in the network.
What is the effect of low power factor in a transmission system?
A Increased losses
B Improved efficiency
C Reduced current
D Increased voltage
A low power factor means that more current is required to deliver the same amount of useful power, leading to higher losses in the transmission lines. This inefficiency can cause overheating and excessive energy consumption, reducing system reliability.
How can reactive power be managed in a power system?
A Increase resistance
B Decrease voltage
C Reduce frequency
D Use of capacitors
Reactive power can be managed by using capacitors, which provide leading reactive power to offset the lagging reactive power caused by inductive loads. This improves voltage regulation and reduces system losses by balancing the power supply.
What is the role of transformers in improving energy efficiency?
A Decrease losses
B Increase voltage
C Stabilize frequency
D Reduce current
Transformers improve energy efficiency by reducing the energy losses during voltage conversion. Efficient transformers operate with minimal core and copper losses, ensuring that most of the electrical energy is transferred without wastage.
What does the term “load shedding” refer to in power distribution systems?
A Voltage regulation
B Power consumption adjustment
C Balancing current
D Power supply interruption
Load shedding refers to the intentional reduction of electrical power supply to certain areas to prevent the entire system from overloading. It is a measure used during periods of high demand or when there is an insufficient power supply.
What is the impact of using energy‐efficient conductors in transmission lines?
A Reduced losses
B Increased voltage
C Higher current
D Increased sag
Energy‐efficient conductors, such as those made with better materials or lower resistance, reduce power losses in transmission lines. This improves overall system efficiency by minimizing energy dissipation as heat during electricity transmission.
What does power factor correction aim to achieve in an electrical system?
A Increase voltage
B Increase efficiency
C Reduce current
D Decrease frequency
Power factor correction aims to increase system efficiency by reducing the phase difference between voltage and current. This helps in reducing the amount of reactive power, which decreases energy losses and improves the overall performance of the system.
Which of the following is a common method of improving power factor?
A Reducing voltage
B Adding inductors
C Using capacitors
D Using transformers
Capacitors are commonly used for power factor correction because they provide leading reactive power, which compensates for the lagging reactive power from inductive loads. This balances the power factor and improves system efficiency.
How does high voltage transmission contribute to energy efficiency?
A Reduces losses
B Increases resistance
C Increases current
D Reduces voltage
High voltage transmission is more energy‐efficient because it reduces the current for the same power level. Since power loss is proportional to the square of the current (I²R), lowering current reduces energy loss in the transmission lines.
What is the main disadvantage of a low power factor in electrical systems?
A Increased voltage instability
B Higher operational costs
C Reduced equipment lifespan
D Increased load balancing
A low power factor leads to inefficient use of electrical power, requiring higher current to deliver the same amount of useful power. This results in higher operational costs, as more energy is consumed and more equipment is needed to handle the increased load.
How do synchronous condensers help with reactive power management?
A Increase voltage
B Provide lagging power
C Decrease power losses
D Provide leading power
Synchronous condensers help manage reactive power by providing leading reactive power to offset the lagging power from inductive loads. This balances the system, improves voltage regulation, and reduces the demand for reactive power from the grid.
What is the effect of overloading on energy efficiency in transmission systems?
A Improved system performance
B Increased losses
C Reduced power loss
D Stable voltage regulation
Overloading a transmission system causes an increase in current, leading to higher resistive losses (I²R losses) and reduced system efficiency. It can also cause overheating, equipment damage, and potential system failures if not managed properly.
What is the purpose of using energy‐efficient transformers?
A To reduce current
B To improve insulation
C To reduce energy loss
D To increase voltage
Energy‐efficient transformers are designed to minimize core and copper losses during power conversion. They are optimized to deliver electrical power with minimal energy wastage, reducing overall system losses and improving the efficiency of the power system.
What is a common indicator of poor power quality in a system?
A Harmonics
B Stable voltage
C High frequency
D Low impedance
Harmonics are unwanted frequencies in the power system that distort the voltage and current waveforms. They can cause overheating in electrical equipment, interfere with communication systems, and degrade overall power quality in a distribution network.