What is the primary purpose of a transformer in a power system?
A Fault isolation
B Voltage conversion
C Voltage regulation
D Power distribution
The primary function of a transformer is to convert voltage levels. It steps up voltage for efficient long distance transmission and steps down voltage for safe consumption by households and industries, making it a crucial component in power systems.
What causes voltage drop in long distance transmission lines?
A Faults
B High voltage
C Low frequency
D Line resistance
Voltage drop in transmission lines occurs due to the resistance of the conductors, which causes energy loss in the form of heat as the electric current flows through the line. This effect increases over longer distances.
What is the function of a step up transformer in a power system?
A Fault isolation
B Decrease voltage
C Increase voltage
D Increase current
A step up transformer increases the voltage from the generator level to a higher level for transmission. Higher voltage reduces the current, which in turn minimizes energy losses during transmission over long distances.
What type of transformer is used to reduce voltage for household consumption?
A Step down transformer
B Auto transformer
C Isolation transformer
D Step up transformer
A step down transformer reduces the voltage from transmission levels to lower, safer levels for use in homes and businesses. It ensures that the voltage is within a safe range for household appliances.
Why are transmission lines typically operated at high voltage?
A To increase current
B To reduce power losses
C To increase power
D To reduce current
Transmission lines operate at high voltage to reduce power losses. Increasing voltage reduces current flow, which decreases resistive losses (I²R losses) in transmission lines, making long distance transmission more efficient.
What does a transmission line’s impedance consist of?
A Reactance
B Resistance
C None of the above
D Both resistance and reactance
Impedance is the total opposition to the flow of alternating current in a transmission line. It consists of both resistance (the opposition to current flow) and reactance (the opposition due to inductive and capacitive components).
What is the main function of a busbar in a substation?
A Fault detection
B Voltage transformation
C Power distribution
D Power generation
A busbar is a metal bar that serves as a central point for distributing electrical power in substations. It connects incoming and outgoing circuits, ensuring the smooth transfer of power throughout the system.
What is the role of a tap changer in a transformer?
A Power storage
B Change voltage
C Increase current
D Change frequency
A tap changer in a transformer allows for adjustment of the voltage ratio by selecting different taps on the transformer winding. This helps regulate output voltage to maintain stability in the power system under varying load conditions.
What happens when the current in a transmission line increases?
A Frequency increases
B Voltage increases
C Voltage drops
D Power loss increases
As current increases in a transmission line, the power loss (I²R loss) increases. Higher current results in more heat generation due to resistance in the transmission line, leading to higher energy losses.
Why are transformers made with laminated cores?
A To reduce losses
B To increase power
C To increase resistance
D To increase voltage
Transformers use laminated cores to reduce eddy current losses. The lamination minimizes the flow of circulating currents within the core, improving the efficiency of the transformer by reducing heat loss and increasing performance.
What is the purpose of an isolation transformer?
A Fault detection
B Electrical isolation
C Voltage transformation
D Power generation
An isolation transformer electrically isolates two circuits to prevent a direct electrical connection. This is typically used for safety purposes, protecting against electric shock and preventing ground loops in sensitive equipment.
What is the key advantage of using a high voltage transmission system?
A Increases efficiency
B Increases current
C Reduces losses
D Both A and B
A high voltage transmission system reduces energy losses and increases transmission efficiency. Higher voltage allows lower current, which reduces resistive losses and improves the overall effectiveness of the power grid over long distances.
How is power transmitted over long distances in a power system?
A Using low frequency
B Using high current
C Using high voltage
D Using low voltage
Power is transmitted over long distances using high voltage to minimize energy losses. High voltage reduces current, which decreases resistive losses (I²R losses) in transmission lines, making long distance transmission more efficient.
What is the typical function of a transmission line’s conductor?
A Voltage conversion
B Power transmission
C Voltage regulation
D Power storage
The primary function of the conductor in a transmission line is to carry electrical power over long distances. The conductor is designed to handle high currents while minimizing losses and maintaining the integrity of the power flow.
What is the role of the core in a transformer?
A Magnetic flux transfer
B Voltage regulation
C Power generation
D Power transmission
The core of a transformer is made of laminated steel and serves to guide the magnetic flux between the primary and secondary windings. This flux transfer allows energy to be efficiently transferred between the windings, enabling voltage transformation.