WorksheetsOvervoltage in Power Systems Quiz
Total questions: 25
Worksheet time: 13mins
Which of the following is a natural cause of overvoltage in power systems?
Switching of capacitor banks
Lightning
Load variations
Tap-changing operations
Switching surges occur mainly due to ________.
Voltage regulation
Closing and opening of circuit breakers
Temperature variations
Conductor sag
Temporary overvoltages are usually associated with ________.
Insulator pollution
Resonance and ground faults
Load shedding
Harmonics
Lightning overvoltage is characterized by ________.
High magnitude and long duration
Low magnitude and long duration
High magnitude and short duration
Low magnitude and short duration
The term "impulse voltage" refers to a voltage with ________.
Slow rise and slow fall
Fast rise and slow fall
Slow rise and fast fall
Fast rise and fast fall
Corona occurs when ________.
Insulation resistance increases
Voltage drops below threshold
Air surrounding the conductor ionizes
Frequency decreases
One common effect of corona is ________.
Increase in insulation strength
Radio interference
Improved power quality
Reduced line reactance
Power loss due to corona increases with ________.
Decrease in humidity
Increase in conductor diameter
Increase in voltage
Decrease in frequency
Bewley Lattice Diagram is used to analyze ________.
Load flow
Travelling waves
Corona inception
Fault currents
For an open-circuited line termination, the travelling wave is ________.
Fully absorbed
Reflected with same polarity
Reflected with opposite polarity
Completely attenuated
Surge arresters protect the system by ________.
Storing energy
Reducing frequency
Limiting overvoltages
Grounding the neutral point
Metal Oxide Varistor (MOV) is commonly used in ________.
Lightning arresters
Circuit breakers
Grounding systems
Transformers
Corona onset voltage depends mainly on ________.
Type of insulator
Conductor diameter and surface condition
Reactive power
Load current
Switching overvoltages are higher in ________.
Low-voltage distribution systems
Underground cables
EHV/UHV transmission lines
LV control circuits
Temporary overvoltages are dangerous mainly because they ________.
Cause fast insulation breakdown
Last longer
Occur at low frequency
Are highly oscillatory
Lightning strokes to transmission lines are minimized by ________.
Bundled conductors
Shield wires
Spacers
Damping resistors
Which component diverts surge currents safely to earth?
Fuse
Reactor
Earthing system
Coupling capacitor
A direct lightning stroke refers to ________.
Lightning hitting a tree
Lightning striking the ground near a substation
Lightning hitting a phase conductor
Induced voltage due to nearby strike
Travelling waves on a line are described by ________.
Maxwell’s equations
Circuit breaker switching curve
Conductivity profile
Generator regulation
Spark gaps are used in surge protection because they ________.
Block DC
Provide a controlled breakdown path
Reduce load current
Increase insulation level
Corona can be reduced by ________.
Using small-diameter conductors
Using bundled conductors
Increasing line frequency
Reducing conductor spacing
The major effect of switching surges in transformers is ________.
Core saturation
Winding insulation stress
Voltage regulation improvement
Increase in efficiency
Overvoltages due to lightning are minimized using ________ on towers.
Anti-vibration dampers
Ground wires
Interphase spacers
Optical cables
In a Bewley diagram, horizontal lines represent ________.
Resistance
Time intervals
Fault current
Magnetic flux
Which of the following does NOT cause temporary overvoltages?
Resonance
Sudden load rejection
Lightning strike
Ungrounded system faults
