What is the primary function of a transformer in a power system?
A Power generation
B Voltage regulation
C Fault isolation
D Voltage conversion
Transformers are used to convert voltage levels in a power system. They step up voltage for efficient long distance transmission and step it down for safe use in homes and industries. They do not generate power.
What is the purpose of using high voltage in transmission lines?
A Increase power generation
B Reduce power loss
C Increase current flow
D Improve voltage stability
High voltage is used in transmission lines to reduce power loss. When voltage is increased, the current decreases, which minimizes the I²R losses in the transmission lines, making the system more efficient.
What type of transformer is used to reduce voltage levels for consumer use?
A Step down transformer
B Auto transformer
C Isolation transformer
D Step up transformer
A step down transformer reduces the high voltage from the transmission system to a lower, safer level suitable for consumer use. It is commonly found in substations before electricity is distributed to homes and businesses.
What is the main function of a transmission line in a power system?
A Fault isolation
B Voltage transformation
C Power transmission
D Power distribution
Transmission lines are responsible for carrying electrical power over long distances from power plants to substations. They use high voltage to minimize energy losses during transmission and ensure efficient delivery to distribution systems.
What happens to the current when the voltage is increased in a power system?
A Remains the same
B Increases
C Fluctuates
D Decreases
According to Ohm’s law, when voltage increases and resistance remains constant, the current decreases. This is why high voltage is used in transmission lines to reduce the current and minimize energy losses.
What is the purpose of using an isolation transformer in a power system?
A Increase voltage
B Electrical isolation
C Prevent faults
D Improve efficiency
An isolation transformer is used to isolate the primary and secondary circuits. It provides electrical isolation between the input and output to protect equipment and reduce the risk of electric shock in certain applications.
What is a common cause of voltage drop in transmission lines?
A High frequency
B High voltage
C Long distance
D Low current
Voltage drop occurs when electrical energy travels long distances through transmission lines. As current flows, resistance in the lines causes a reduction in voltage, which is why voltage is stepped up for long distance transmission.
What type of losses occur in transmission lines due to resistance?
A Copper losses
B Dielectric losses
C Core losses
D Iron losses
Copper losses occur due to the resistance in the transmission lines, where some energy is lost as heat. These losses are proportional to the square of the current (I²R) and increase with higher current.
What is the function of a tap changer in a transformer?
A Power distribution
B Fault detection
C Voltage conversion
D Voltage regulation
A tap changer is used in transformers to regulate the output voltage by selecting different tapping points on the transformer’s winding. This helps to maintain a stable voltage in the system, particularly under varying load conditions.
What is the role of transmission towers in a power system?
A Power storage
B Support for transmission lines
C Power generation
D Voltage regulation
Transmission towers are structures that support overhead transmission lines, ensuring that the lines are kept at the required height and tension for safe and efficient power delivery over long distances.
What does the primary winding of a transformer do?
A Increases voltage
B Decreases voltage
C Receives the input power
D Converts current to voltage
The primary winding of a transformer receives input power, which is typically at high voltage. It generates a magnetic field that induces voltage in the secondary winding, which is then transformed to the desired level.
What is the primary purpose of a transformer’s core?
A Power generation
B Voltage conversion
C Fault detection
D Magnetic flux transfer
The transformer core is made of magnetic materials and serves to transfer the magnetic flux between the primary and secondary windings. It plays a crucial role in efficiently transferring energy in the transformer.
What is the role of the secondary winding of a transformer?
A Supplies input power
B Decreases voltage
C Generates electricity
D Increases voltage
The secondary winding of a transformer delivers the output power after the voltage has been transformed from the primary winding. Depending on the transformer type, it either steps up or steps down the voltage.
What is the term for the resistance of a transmission line to the flow of alternating current?
A Impedance
B Reactance
C Conductance
D Resistance
Impedance is the total opposition to the flow of alternating current (AC) in a transmission line, which includes both resistance and reactance. It affects the efficiency and the voltage drop along the transmission line.
What does power system modeling help to simulate?
A Generation fuel costs
B System behavior under different conditions
C Renewable energy generation
D Power losses during transmission
Power system modeling simulates how the system behaves under various operating conditions, such as load changes, faults, or system expansions. It helps engineers plan, optimize, and ensure the reliable operation of the grid under different scenarios.