What is the primary function of reactive power in a power system?
A Frequency regulation
B Power storage
C Power generation
D Voltage support
Reactive power does not perform useful work but is essential for maintaining voltage levels in the power system. It supports the operation of inductive loads like motors and transformers, helping to stabilize the voltage across the grid.
What is the main difference between active power and reactive power?
A Active power does work, reactive power does not
B Active power is used in transmission, reactive power in generation
C Reactive power is always higher than active power
D Active power stores energy, reactive power does not
Active power (measured in watts) is the power that performs useful work, such as lighting or heating, while reactive power (measured in VARs) does not perform any work but is necessary for maintaining voltage levels in the system.
What is the main goal of power factor correction?
A Increase voltage
B Increase power generation
C Improve efficiency
D Reduce power losses
Power factor correction is used to improve the efficiency of a power system by reducing the phase difference between voltage and current. This leads to a more efficient use of electrical power and reduces transmission losses.
What happens when the power factor is too low in a power system?
A Voltage drop
B Increased transmission losses
C Better power generation
D Improved system stability
A low power factor means that the system is inefficient because more current is needed to deliver the same amount of active power. This increases losses in the transmission lines and reduces overall system efficiency.
What does active power represent in a power system?
A Power used to perform work
B Total power
C Power lost in the system
D Power used to maintain voltage
Active power, measured in watts, represents the actual power used to perform useful work in the system, such as running motors, lighting, and heating. It is the power that does real work in an electrical circuit.
What device is commonly used for power factor correction?
A Transformer
B Capacitor bank
C Generator
D Circuit breaker
Capacitor banks are commonly used for power factor correction. They provide reactive power to the system, helping to reduce the phase difference between current and voltage, which improves the overall power factor and system efficiency.
What effect does improving the power factor have on a power system?
A Decreases the load
B Increases losses
C Increases voltage
D Increases the efficiency of the system
Improving the power factor reduces the amount of reactive power in the system, which decreases current flow and transmission losses. This leads to a more efficient system, reducing energy waste and enhancing system capacity.
Which type of load typically consumes reactive power?
A Capacitive load
B Active load
C Inductive load
D Resistive load
Inductive loads, such as motors, transformers, and coils, consume reactive power. These loads create magnetic fields that require reactive power to sustain them, which is essential for their operation but does no useful work.
How is power factor corrected in an industrial setting?
A By reducing transmission voltage
B By increasing active power generation
C By using reactive power compensation equipment
D By increasing current
In industrial settings, power factor is corrected by using reactive power compensation equipment, such as capacitor banks or synchronous condensers. These devices provide the necessary reactive power to balance the inductive loads and improve the power factor.
What does a lagging power factor indicate?
A High system efficiency
B Excessive active power
C Voltage stability
D Excessive reactive power
A lagging power factor typically indicates the presence of inductive loads in the system, which consume excessive reactive power. This leads to inefficiencies and increased losses, as the current lags behind the voltage in the system.
What is the consequence of a leading power factor in a power system?
A Reduced efficiency
B Voltage instability
C Increased losses
D Overvoltage
A leading power factor occurs when the current leads the voltage, usually due to capacitive loads. This can cause overvoltage conditions, which may damage equipment and lead to instability in the power system.
Which type of power is responsible for performing work in an electrical system?
A Active power
B Complex power
C Reactive power
D Apparent power
Active power is the power that performs useful work in an electrical system, such as running motors, lighting lamps, and heating. It is the real power measured in watts and is essential for most electrical applications.
What does the power factor correction mainly improve in a power system?
A System capacity
B Frequency regulation
C Power transmission efficiency
D Voltage stability
Power factor correction improves the efficiency of power transmission by reducing the amount of reactive power needed. This decreases the total current in the system, reducing losses and improving the overall transmission efficiency.
What is the impact of reactive power on the overall power system?
A Decreases system efficiency
B Helps maintain voltage levels
C Increases total power output
D Reduces transmission losses
Reactive power does not perform useful work but is essential for maintaining voltage levels in the power system. It helps sustain the voltage needed for the system to function properly, especially for inductive loads like motors.
What is the typical unit of measurement for active power?
A Watts
B Ampere
C Volt amps reactive
D Volt amps
Active power is measured in watts (W) and represents the actual power used to perform work. It is the real power in an electrical system and is the product of voltage, current, and the cosine of the phase angle between them.