Q.1 What is the typical peak voltage of a direct lightning strike on a high‑tension tower?
0.5–1 kV
5–10 kV
50–100 kV
500–1 000 kV
Explanation - Lightning channels carry mega‑volt potentials, often exceeding 500 kV.
Correct answer is: 500–1 000 kV
Q.2 Which component is most effective at limiting surge voltage to equipment during a lightning strike?
Metal‑oxide varistor (MOV)
Fuse
Capacitor bank
Resistor ladder
Explanation - MOVs clamp voltage spikes by changing resistance quickly.
Correct answer is: Metal‑oxide varistor (MOV)
Q.3 Switch‑on overvoltage is primarily caused by:
Capacitive voltage rise
Inductive voltage rise
Dielectric breakdown
Resistive heating
Explanation - Opening a switch abruptly releases stored magnetic energy, raising voltage.
Correct answer is: Inductive voltage rise
Q.4 The time constant of an RC surge arrester determines:
Maximum voltage it can block
Rise time of the surge
Current rating
Power dissipation
Explanation - RC time constant defines how quickly voltage rises before the arrester conducts.
Correct answer is: Rise time of the surge
Q.5 Which phenomenon causes a high‑voltage line to become charged during a cloud‑to‑ground flash?
Corona discharge
Capacitive coupling
Inductive coupling
Triboelectric charging
Explanation - The lightning channel capacitively couples energy to nearby conductors.
Correct answer is: Capacitive coupling
Q.6 A surge protector with a clamping voltage of 4 kV will:
Never allow voltages above 4 kV to reach the load
Clamp to 4 kV only when current exceeds threshold
Operate only for DC surges
Protect only the power source
Explanation - The device conducts when voltage exceeds its breakdown threshold.
Correct answer is: Clamp to 4 kV only when current exceeds threshold
Q.7 Which of the following is a key parameter for designing a lightning protection system?
Ground rod length
Line voltage
Switching frequency
Capacitance per meter
Explanation - Longer rods lower resistance, improving discharge path to earth.
Correct answer is: Ground rod length
Q.8 In a lightning strike, the air above the channel behaves as a:
High‑resistance plasma
Low‑resistance plasma
Superconductor
Perfect insulator
Explanation - Ionization creates a conductive path, lowering resistance dramatically.
Correct answer is: Low‑resistance plasma
Q.9 What is the primary purpose of a surge‑gap in high‑voltage lines?
To increase voltage
To provide a controlled discharge path
To reduce current
To filter noise
Explanation - Surge gaps safely divert excess energy to earth.
Correct answer is: To provide a controlled discharge path
Q.10 Which parameter is most critical for a MOV’s longevity?
Rated voltage
Capacitance
Number of surge cycles
Physical size
Explanation - Each surge slightly degrades the MOV, reducing life expectancy.
Correct answer is: Number of surge cycles
Q.11 During a switching surge, the voltage spike primarily follows which relationship?
V = L × di/dt
V = C × dI/dt
V = R × I
V = 1/LC
Explanation - The inductance generates voltage when current changes rapidly.
Correct answer is: V = L × di/dt
Q.12 Lightning-induced overvoltage can be mitigated by:
Installing fuses only
Using high‑voltage transformers
Employing surge arresters
Increasing conductor resistance
Explanation - Arresters clamp excess voltage to safe levels.
Correct answer is: Employing surge arresters
Q.13 The term 'surge impedance ratio' (SIR) refers to:
The ratio of surge voltage to surge current
The ratio of voltage to current in a surge arrester
The ratio of the surge path impedance to system impedance
The ratio of the rated voltage to clamping voltage
Explanation - SIR indicates how effectively a surge can be diverted.
Correct answer is: The ratio of the surge path impedance to system impedance
Q.14 Which of the following is not a typical lightning protection component?
Air terminals
Ground conductors
Surge arresters
Heat sinks
Explanation - Heat sinks are unrelated to lightning protection.
Correct answer is: Heat sinks
Q.15 A lightning strike can generate a shockwave that produces which acoustic phenomenon?
Boom
Whistle
Click
Ring
Explanation - The rapid expansion creates a loud thunderous boom.
Correct answer is: Boom
Q.16 The rise time of a typical lightning surge is:
10 ns
100 µs
1 ms
10 s
Explanation - Lightning rise times are extremely fast, on the order of nanoseconds.
Correct answer is: 10 ns
Q.17 In high‑voltage engineering, the breakdown voltage of air is approximately:
3 kV/m
3 V/m
3 MV/m
3 GV/m
Explanation - Standard breakdown occurs at about 3 kV per meter of air.
Correct answer is: 3 kV/m
Q.18 Which safety class for surge arresters provides the lowest clamping voltage?
Class A
Class B
Class C
Class D
Explanation - Class A arresters clamp at the lowest voltages, offering tighter protection.
Correct answer is: Class A
Q.19 A high‑voltage line is susceptible to lightning induced transients mainly because:
It has high resistance
It is electrically isolated
It acts as an antenna
It contains capacitors
Explanation - Long conductors couple to lightning fields like an antenna.
Correct answer is: It acts as an antenna
Q.20 Which device is used to protect electronic equipment from overvoltage during switching?
Switching regulator
Surge protector
Isolation transformer
Diode bridge
Explanation - Surge protectors clamp transient surges to safe levels.
Correct answer is: Surge protector
Q.21 The energy stored in a capacitor used for surge protection is given by:
E = ½ CV²
E = CV
E = I²R
E = V/R
Explanation - Standard capacitor energy formula applies.
Correct answer is: E = ½ CV²
Q.22 Which law explains why lightning prefers the lowest resistance path?
Gauss’s Law
Kirchhoff’s Voltage Law
Kirchhoff’s Current Law
Ohm’s Law
Explanation - Current follows paths of lowest resistance per Ohm’s Law.
Correct answer is: Ohm’s Law
Q.23 A surge arrester’s clamping voltage is typically higher than its:
Rated voltage
Surge current rating
Breakdown voltage
Operating temperature
Explanation - Clamping voltage is set above rated to avoid accidental tripping.
Correct answer is: Rated voltage
Q.24 During a lightning strike, the air temperature can rise to:
100 °C
1 000 °C
10 000 °C
100 000 °C
Explanation - Lightning channels reach temperatures near 30 000 °C, but 10 000 °C is typical for surge.
Correct answer is: 10 000 °C
Q.25 A key design parameter for a lightning rod is its:
Length relative to tower height
Material conductivity
Electrical resistance
Color
Explanation - Rod height determines effective coupling to air and safety distance.
Correct answer is: Length relative to tower height
Q.26 What is the function of a spark gap in high‑voltage surge protection?
To store energy
To limit current
To provide a controlled discharge path
To filter AC noise
Explanation - Spark gaps allow rapid arcing to ground when voltage exceeds threshold.
Correct answer is: To provide a controlled discharge path
Q.27 Switch‑off surges are often mitigated by:
Adding series resistance
Using soft‑start circuits
Installing reverse‑polarization protection
Increasing supply voltage
Explanation - Soft‑start controls the rate of current change, reducing voltage spikes.
Correct answer is: Using soft‑start circuits
Q.28 Which of the following is NOT a characteristic of lightning?
High current
High voltage
Long duration
Short duration
Explanation - Lightning is brief, typically a few microseconds to milliseconds.
Correct answer is: Long duration
Q.29 The clamping voltage of a surge arrester is measured under a:
Low‑frequency test
High‑frequency test
Standard surge test
Temperature test
Explanation - Industry standards specify test conditions for clamping voltage.
Correct answer is: Standard surge test
Q.30 When designing a lightning protection system, the spacing between conductors must account for:
Capacitive coupling
Resistive heating
Mechanical vibration
Electrical insulation
Explanation - Close conductors increase coupling, raising surge risk.
Correct answer is: Capacitive coupling
Q.31 Which of the following best describes a switching overvoltage?
A sustained high voltage
A transient voltage spike
A drop in voltage
A constant AC ripple
Explanation - Switching surges are brief, high‑amplitude transients.
Correct answer is: A transient voltage spike
Q.32 The maximum surge current that a MOV can absorb is called its:
Peak surge current rating
Continuous current rating
Short‑circuit current rating
Surge endurance rating
Explanation - This rating limits the instantaneous current the MOV can tolerate.
Correct answer is: Peak surge current rating
Q.33 What is the purpose of a grounding rod in a lightning protection system?
To increase voltage
To provide a low‑resistance path to earth
To store energy
To reflect lightning
Explanation - Grounding rods safely dissipate lightning energy into earth.
Correct answer is: To provide a low‑resistance path to earth
Q.34 Which of the following is a common consequence of unprotected switching surges?
Thermal runaway
Increased efficiency
Reduced noise
Improved reliability
Explanation - Surges can damage insulation, causing overheating and failure.
Correct answer is: Thermal runaway
Q.35 Lightning can produce which of these electromagnetic phenomena?
Electromagnetic pulse (EMP)
Static electricity
Magnetostatic field
Acoustic wave
Explanation - Lightning generates a strong, short EM pulse.
Correct answer is: Electromagnetic pulse (EMP)
Q.36 The energy of a typical lightning strike can reach:
10 kJ
10 MJ
10 GJ
10 TJ
Explanation - Lightning energies are on the order of mega‑joules.
Correct answer is: 10 MJ
Q.37 Which type of transformer is most vulnerable to lightning-induced surges?
Step‑down transformer
Isolation transformer
Step‑up transformer
Regulating transformer
Explanation - High voltage side is exposed to surge paths.
Correct answer is: Step‑up transformer
Q.38 In surge arresters, the breakdown voltage is primarily determined by:
Material bandgap
Arrester geometry
Ambient temperature
Operating frequency
Explanation - Geometry controls electric field concentration, affecting breakdown.
Correct answer is: Arrester geometry
Q.39 The term 'storm‑surge' refers to:
A surge from a lightning strike
A surge from a power line
A surge from a transformer fault
A surge from a generator fault
Explanation - Storm surges are caused by atmospheric electrical events.
Correct answer is: A surge from a lightning strike
Q.40 What is a characteristic of a corona discharge?
Occurs at high voltage
Generates a bright flash
Requires a spark gap
Occurs only in vacuum
Explanation - Corona appears when electric field exceeds ionization threshold.
Correct answer is: Occurs at high voltage
Q.41 Which parameter is used to express the ability of a surge arrester to withstand multiple surges?
Surge endurance rating
Voltage rating
Current rating
Temperature rating
Explanation - It indicates how many surges the arrester can absorb before failure.
Correct answer is: Surge endurance rating
Q.42 A high‑voltage line’s susceptibility to lightning can be reduced by:
Installing isolation transformers
Adding series resistors
Using thicker conductors
Shortening the line
Explanation - Larger cross‑section reduces inductance, lowering surge magnitude.
Correct answer is: Using thicker conductors
Q.43 Which of these is NOT a typical component of a lightning protection system?
Air terminal
Surge arrester
Ground rod
Capacitor bank
Explanation - Capacitor banks are not standard for lightning protection.
Correct answer is: Capacitor bank
Q.44 When a high‑voltage conductor is struck by lightning, the surge travels:
Only along the conductor
Only into the earth
Both conductor and earth
Only through air
Explanation - Energy splits between the conductor path and the ground.
Correct answer is: Both conductor and earth
Q.45 The speed of a lightning discharge is comparable to:
The speed of sound
The speed of light
The speed of a car
The speed of a boat
Explanation - Lightning propagates near light speed along the channel.
Correct answer is: The speed of light
Q.46 The term 'breakdown voltage' refers to:
The maximum voltage a conductor can handle
The voltage at which a dielectric fails
The voltage at which a fuse blows
The voltage at which a transformer saturates
Explanation - Breakdown causes a sudden increase in current.
Correct answer is: The voltage at which a dielectric fails
Q.47 Which device is designed to clamp transient overvoltages to protect equipment?
Resistor
Capacitor
Varistor
Inductor
Explanation - Varistors are voltage‑dependent resistors that conduct under high voltage.
Correct answer is: Varistor
Q.48 In surge arrester design, the term 'clamping voltage' refers to:
The highest voltage allowed on the arrester
The voltage at which the arrester starts to conduct
The maximum voltage the arrester can withstand
The voltage drop across the arrester
Explanation - Clamping voltage marks the onset of protective conduction.
Correct answer is: The voltage at which the arrester starts to conduct
Q.49 Which of the following is a main advantage of using a spark gap over a varistor?
Higher energy absorption
Lower cost
Lower clamping voltage
Smaller size
Explanation - Spark gaps can handle very high surge energies.
Correct answer is: Higher energy absorption
Q.50 A lightning strike can induce a surge voltage of up to how many kilovolts?
10 kV
100 kV
1 000 kV
10 000 kV
Explanation - Lightning can generate up to a million volts.
Correct answer is: 1 000 kV
Q.51 The most common frequency of switching surges in power systems is:
50–60 Hz
1–10 Hz
10–100 Hz
1–10 kHz
Explanation - Switching surges are superimposed on the AC mains frequency.
Correct answer is: 50–60 Hz
Q.52 Lightning protection requires a minimum distance from:
The nearest building
The nearest person
The ground rod
The highest point of the structure
Explanation - Ensures safe path for discharge.
Correct answer is: The highest point of the structure
Q.53 The capacitance between a lightning rod and ground is usually:
Very low
Moderate
Very high
Zero
Explanation - Large spacing reduces capacitance to limit surge energy.
Correct answer is: Very low
Q.54 Which of the following is an effect of a lightning strike on a power transformer?
Reversible heating
Permanent magnetization
Mechanical deformation
All of the above
Explanation - Lightning can damage transformers in multiple ways.
Correct answer is: All of the above
Q.55 The speed at which a surge propagates along a conductor is:
Speed of light
Speed of sound
Speed of electricity
Speed of water
Explanation - Surge travels at close to light speed along conductors.
Correct answer is: Speed of light
Q.56 Which of the following is not a typical characteristic of a surge arrester?
High reverse voltage
Low series resistance
High surge current rating
Low energy absorption
Explanation - Surge arresters must absorb large surge energies.
Correct answer is: Low energy absorption
Q.57 Lightning is most likely to strike:
Water bodies
Tall structures
Low‑lying areas
All of the above
Explanation - Tall structures present lower resistance paths to ground.
Correct answer is: Tall structures
Q.58 The rate of rise of voltage in a switching surge is often expressed as:
dV/dt
dI/dt
V/I
I/V
Explanation - Rate of voltage rise is a key design parameter.
Correct answer is: dV/dt
Q.59 The primary reason for using a grounding electrode in a lightning system is to:
Increase the system voltage
Provide a low‑impedance discharge path
Reduce current flow
Store energy
Explanation - Grounding ensures safe dissipation of lightning energy.
Correct answer is: Provide a low‑impedance discharge path
Q.60 A surge arrester's effectiveness depends on its:
Breakdown voltage
Physical size
Ambient temperature
Color
Explanation - Breakdown voltage sets the threshold for protection.
Correct answer is: Breakdown voltage
Q.61 Which of the following best describes a lightning-induced surge?
A continuous high voltage
A transient spike
A low frequency oscillation
A DC offset
Explanation - Lightning surges are short, high‑magnitude transients.
Correct answer is: A transient spike
Q.62 The term 'clamping voltage' is used for:
The maximum voltage a device can withstand
The voltage at which a protective device starts to conduct
The voltage across a resistor
The voltage across a capacitor
Explanation - Clamping voltage defines the protective threshold.
Correct answer is: The voltage at which a protective device starts to conduct
Q.63 During a lightning strike, the induced voltage on an isolated conductor is due to:
Capacitive coupling
Inductive coupling
Resistive coupling
Chemical coupling
Explanation - Lightning creates a changing electric field that induces voltage.
Correct answer is: Capacitive coupling
Q.64 A high‑voltage surge can damage electronic equipment by:
Increasing resistance
Breaking down insulation
Reducing current
Enhancing efficiency
Explanation - Surges exceed insulation voltage, causing arcing.
Correct answer is: Breaking down insulation
Q.65 Which component is most suitable for protecting low‑voltage electronics from surges?
Metal‑oxide varistor (MOV)
Fuse
Transformer
Inductor
Explanation - MOVs clamp surges to safe levels for low‑voltage circuits.
Correct answer is: Metal‑oxide varistor (MOV)
Q.66 The energy of a lightning surge can be calculated using:
E = ½ CV²
E = V/I
E = I²R
E = P × t
Explanation - Standard capacitor energy formula applies to surge storage.
Correct answer is: E = ½ CV²
Q.67 The most common form of lightning is:
Cloud‑to‑ground
Intra‑cloud
Ground‑to‑ground
All of the above
Explanation - It is the type that most frequently interacts with structures.
Correct answer is: Cloud‑to‑ground
Q.68 The surge impedance ratio (SIR) is a parameter used to:
Determine the size of a conductor
Design lightning rods
Assess surge protection effectiveness
Calculate line resistance
Explanation - SIR compares surge path impedance to system impedance.
Correct answer is: Assess surge protection effectiveness
Q.69 Which type of lightning damage is caused by a high‑voltage transient?
Physical cracking
Electromagnetic interference
Thermal burns
All of the above
Explanation - Surges can damage equipment mechanically, electrically, and thermally.
Correct answer is: All of the above
Q.70 The standard test for MOV clamping voltage is conducted at:
1 kV
10 kV
100 kV
1 MV
Explanation - Testing simulates realistic surge conditions.
Correct answer is: 1 kV
Q.71 Which component can provide a surge path with low impedance during a lightning strike?
Spark gap
Resistor
Inductor
Capacitor
Explanation - Spark gaps short the surge to ground.
Correct answer is: Spark gap
Q.72 A surge arrester’s energy absorption rating is expressed in:
Watts
Joules
Volts
Amperes
Explanation - Energy is measured in joules for surge protection.
Correct answer is: Joules
Q.73 Which of the following is a direct result of a lightning strike on a high‑voltage line?
Permanent voltage drop
Temporary voltage surge
Permanent line break
All of the above
Explanation - Surges are temporary and often recover after the strike.
Correct answer is: Temporary voltage surge
Q.74 The typical peak current of a lightning flash can reach:
10 A
1 kA
100 kA
1 MA
Explanation - Lightning currents are in the tens to hundreds of kilo‑amps.
Correct answer is: 100 kA
Q.75 Which of the following is not a typical protective measure against switching surges?
Snubber circuits
Soft‑start devices
Thermal fuses
Varistors
Explanation - Thermal fuses protect against overheating, not surges.
Correct answer is: Thermal fuses
Q.76 In high‑voltage systems, a surge’s energy is often stored in the:
Line inductance
Line capacitance
Both inductance and capacitance
Neither
Explanation - Both electrical properties store surge energy.
Correct answer is: Both inductance and capacitance
Q.77 Which parameter is crucial for a lightning rod’s effectiveness?
Length
Material
Color
Shape
Explanation - Rod length determines the height above the structure for effective discharge.
Correct answer is: Length
Q.78 Which of the following describes a switching surge?
A continuous high voltage
A short‑duration high voltage spike
A low voltage drop
A steady DC voltage
Explanation - Switching surges are brief transients.
Correct answer is: A short‑duration high voltage spike
Q.79 A surge protector’s clamping voltage should be:
Lower than the device’s operating voltage
Higher than the device’s operating voltage
Equal to the device’s operating voltage
Unrelated to the operating voltage
Explanation - It must allow normal operation while protecting from transients.
Correct answer is: Higher than the device’s operating voltage
Q.80 A lightning strike can cause:
Ground potential rise
Voltage spikes
Both A and B
Neither
Explanation - Both effects are common in lightning events.
Correct answer is: Both A and B
Q.81 The speed of a surge traveling through a transmission line is close to:
Speed of light in vacuum
Speed of sound
Speed of water
Speed of a car
Explanation - Surges propagate at a fraction of light speed in conductors.
Correct answer is: Speed of light in vacuum
Q.82 Which of the following is an essential feature of a surge arrester?
High reverse voltage
Low series resistance
Low surge current rating
Low capacitance
Explanation - Low series resistance allows fast energy dissipation.
Correct answer is: Low series resistance
Q.83 Which of these is a common type of lightning protection device?
Air terminal
Ground rod
Surge arrester
All of the above
Explanation - All devices are used in protection systems.
Correct answer is: All of the above
Q.84 The maximum voltage a surge arrester can tolerate before conduction begins is:
Breakdown voltage
Clamping voltage
Operating voltage
Rated voltage
Explanation - Breakdown voltage triggers conduction.
Correct answer is: Breakdown voltage
Q.85 Lightning is primarily an example of:
Electrostatic discharge
Electromagnetic induction
Electrochemical reaction
Thermal conduction
Explanation - It is a discharge of static electricity.
Correct answer is: Electrostatic discharge
Q.86 Which of these is an effect of a surge on a power transformer?
Core saturation
Insulation breakdown
Cooling loss
All of the above
Explanation - Surges can cause multiple failures.
Correct answer is: All of the above
Q.87 Which component in a high‑voltage system is most likely to be damaged by a lightning strike?
Capacitor bank
Resistor
Transformer core
Inductor
Explanation - Transformers are vulnerable to high voltage transients.
Correct answer is: Transformer core
Q.88 The typical duration of a lightning strike is:
10 ns
1 µs
10 µs
1 s
Explanation - Lightning lasts on the order of microseconds.
Correct answer is: 10 µs
Q.89 The principle that allows a lightning rod to safely direct a strike to ground is:
Faraday cage effect
Electrostatic shielding
Potential gradient reduction
Inductive coupling
Explanation - The rod lowers the electric field near the structure.
Correct answer is: Potential gradient reduction
Q.90 Which device is used to protect against both lightning surges and switching surges?
Varistor
Fuse
Relay
Capacitor bank
Explanation - Varistors clamp a wide range of transients.
Correct answer is: Varistor
Q.91 The term 'ground potential rise' refers to:
Rise in voltage at the earth surface due to a nearby lightning strike
Increase in voltage of a ground wire
Rise in voltage of a grounded conductor
None of the above
Explanation - Ground potential rise is caused by the lightning channel’s charge transfer.
Correct answer is: Rise in voltage at the earth surface due to a nearby lightning strike
Q.92 A surge arrester typically has:
Low reverse voltage
High clamping voltage
Low surge current rating
High energy absorption capacity
Explanation - It must handle large surge energies.
Correct answer is: High energy absorption capacity
Q.93 Which of the following best describes a cloud‑to‑ground lightning strike?
It originates from ground and goes to cloud
It originates from cloud and goes to ground
It stays within the cloud
It does not involve charge transfer
Explanation - Classic lightning type.
Correct answer is: It originates from cloud and goes to ground
Q.94 The energy dissipated in a surge arrester during a surge is:
E = ½ CV²
E = I²R
E = VI
E = P × t
Explanation - Joule heating dominates energy dissipation.
Correct answer is: E = I²R
Q.95 What is the primary function of a spark gap?
Store energy
Conduct energy to ground
Limit current
Filter noise
Explanation - It provides a low‑resistance path during surges.
Correct answer is: Conduct energy to ground
Q.96 Which parameter is NOT used in specifying a surge arrester?
Clamping voltage
Surge energy absorption
Rated current
Color
Explanation - Color is irrelevant to performance.
Correct answer is: Color
Q.97 A lightning strike can induce a surge that lasts:
Seconds
Milliseconds
Microseconds
Days
Explanation - Surge duration is very brief.
Correct answer is: Microseconds
Q.98 Which of the following is a typical measure to mitigate lightning damage to power lines?
Installing surge arresters
Using thicker conductors
Adding more fuses
All of the above
Explanation - All measures help reduce damage.
Correct answer is: All of the above
Q.99 In high‑voltage systems, a switching surge is caused by:
Rapid change in current
Slow change in voltage
Constant current
Constant voltage
Explanation - Fast dI/dt induces voltage spikes.
Correct answer is: Rapid change in current
Q.100 The term 'surge impedance' refers to:
The resistance of a surge arrester
The impedance of the surge path
The impedance of the load
The impedance of the power source
Explanation - It determines how surges travel through the system.
Correct answer is: The impedance of the surge path
Q.101 Which of the following is not a typical characteristic of lightning?
High current
High voltage
Long duration
Rapid rise time
Explanation - Lightning events are brief.
Correct answer is: Long duration
Q.102 A surge arrester’s energy rating is expressed in:
Joules
Watts
Volts
Amperes
Explanation - Energy absorption is measured in joules.
Correct answer is: Joules
Q.103 The most common type of lightning rod used on power towers is:
Metal tip
Metal cylinder
Metal strip
All of the above
Explanation - Metal tips concentrate electric field.
Correct answer is: Metal tip
Q.104 In a lightning protection system, the term 'ground electrode' refers to:
The conductor that connects the system to the earth
The lightning rod itself
The protective device
The transformer
Explanation - Ground electrodes provide a low‑impedance path.
Correct answer is: The conductor that connects the system to the earth
Q.105 Which of the following devices is used to protect electronic equipment from switching surges?
Varistor
Fuse
Relay
Capacitor
Explanation - Varistors clamp surges effectively.
Correct answer is: Varistor
Q.106 The peak voltage of a lightning channel can exceed:
1 kV
10 kV
100 kV
1 000 kV
Explanation - Lightning peaks in the hundreds of kilovolts to millions of volts range.
Correct answer is: 1 000 kV
Q.107 The clamping voltage of a surge arrester is usually:
Lower than the device’s operating voltage
Higher than the device’s operating voltage
Equal to the device’s operating voltage
Unrelated to the device’s operating voltage
Explanation - Allows normal operation while protecting from transients.
Correct answer is: Higher than the device’s operating voltage
Q.108 A lightning strike can produce a surge that lasts for:
Nanoseconds
Microseconds
Milliseconds
Seconds
Explanation - Surge durations are extremely short.
Correct answer is: Microseconds
Q.109 Which of the following is a typical consequence of an unprotected switching surge?
Equipment failure
Increased efficiency
Lower voltage
All of the above
Explanation - Surges can damage components.
Correct answer is: Equipment failure
Q.110 The main purpose of a spark gap is to:
Store energy
Conduct current to ground during surges
Limit current
Filter noise
Explanation - It provides a low‑resistance path for surges.
Correct answer is: Conduct current to ground during surges
Q.111 The energy of a lightning strike is typically on the order of:
10 kJ
10 MJ
10 GJ
10 TJ
Explanation - Lightning energies reach mega‑joule levels.
Correct answer is: 10 MJ
Q.112 Which of the following best describes a lightning-induced transient?
Long‑duration voltage rise
Short‑duration voltage spike
Constant DC offset
Low‑frequency oscillation
Explanation - Lightning transients are brief and high amplitude.
Correct answer is: Short‑duration voltage spike
Q.113 The primary function of a surge arrester is to:
Absorb surge energy
Amplify voltage
Reduce current
Increase resistance
Explanation - It protects equipment by clamping transients.
Correct answer is: Absorb surge energy
Q.114 Lightning protection systems usually include:
Air terminals
Grounding conductors
Surge arresters
All of the above
Explanation - All are needed for effective protection.
Correct answer is: All of the above
Q.115 Which of the following is a key design parameter for a surge arrester?
Breakdown voltage
Resistive heating
Mechanical strength
Color
Explanation - Breakdown voltage determines protection threshold.
Correct answer is: Breakdown voltage
Q.116 A lightning strike on a high‑voltage line can cause:
A temporary voltage surge
A permanent voltage drop
A permanent line break
All of the above
Explanation - The line typically recovers after the strike.
Correct answer is: A temporary voltage surge
Q.117 The most common type of lightning protection device used on towers is:
Metal tip rod
Metal strip rod
Metal cylinder rod
All of the above
Explanation - Tips concentrate electric field for safe discharge.
Correct answer is: Metal tip rod
Q.118 The surge impedance ratio (SIR) of a transmission line is defined as:
The ratio of line impedance to surge path impedance
The ratio of surge path impedance to system impedance
The ratio of voltage to current
The ratio of voltage to resistance
Explanation - It indicates how surges will behave in the system.
Correct answer is: The ratio of surge path impedance to system impedance
Q.119 Lightning strikes often produce which type of electromagnetic effect?
EM pulse
EM wave
Static field
Magnetic field only
Explanation - Lightning generates short electromagnetic pulses.
Correct answer is: EM pulse
Q.120 Which device is used to clamp a surge to a safe voltage level?
Varistor
Fuse
Inductor
Capacitor bank
Explanation - Varistors provide voltage‑dependent conduction.
Correct answer is: Varistor
Q.121 A lightning strike can increase ground potential by:
A few millivolts
A few volts
A few hundred volts
A few kilovolts
Explanation - Ground potential rise can reach high levels during strikes.
Correct answer is: A few hundred volts
Q.122 Which of the following is an effect of a lightning strike on power lines?
Insulation damage
Core saturation
Both A and B
None of the above
Explanation - Lightning can damage insulation and cores.
Correct answer is: Both A and B
Q.123 Which component is NOT commonly used to mitigate switching surges?
Varistor
Snubber
Capacitor bank
Resistor ladder
Explanation - Capacitor banks are not typical for surge mitigation.
Correct answer is: Capacitor bank
Q.124 The clamping voltage of a surge arrester is the voltage at which it:
Stops conducting
Begins conducting
Opens the circuit
Releases stored energy
Explanation - At clamping voltage the arrester starts to conduct.
Correct answer is: Begins conducting
Q.125 The peak current of a typical lightning strike is:
10 A
100 A
1 kA
10 kA
Explanation - Lightning currents reach kilo‑amp levels.
Correct answer is: 10 kA
Q.126 Lightning protection for high‑voltage lines often involves:
Surge arresters
Ground rods
Both A and B
None of the above
Explanation - Both devices are required for protection.
Correct answer is: Both A and B
Q.127 The main purpose of a metal‑oxide varistor (MOV) is to:
Clamp voltage spikes
Store energy
Reduce current
Increase resistance
Explanation - MOVs quickly conduct under high voltage.
Correct answer is: Clamp voltage spikes
Q.128 Which of the following is a typical characteristic of a lightning channel?
High resistance
Low resistance plasma
No current
High impedance
Explanation - The channel becomes a low‑resistance plasma path.
Correct answer is: Low resistance plasma
Q.129 A surge arrester’s energy absorption rating is given in:
Joules
Watts
Amperes
Volts
Explanation - Energy absorption is measured in joules.
Correct answer is: Joules
Q.130 Which of the following is NOT a typical protection device against lightning?
Ground rod
Air terminal
Varistor
Transformer core
Explanation - Transformer cores are part of equipment, not protection.
Correct answer is: Transformer core
Q.131 The term 'ground potential rise' refers to:
Rise in voltage at the earth surface due to a nearby lightning strike
Rise in voltage of the grounding conductor
Rise in voltage of the line
Rise in voltage of the transformer core
Explanation - Ground potential rise occurs when lightning strikes near a structure.
Correct answer is: Rise in voltage at the earth surface due to a nearby lightning strike
Q.132 A lightning strike can produce a surge of up to:
10 kV
100 kV
1 000 kV
10 000 kV
Explanation - Lightning peaks in the mega‑volt range.
Correct answer is: 1 000 kV
Q.133 Which device is used to protect against both lightning surges and switching surges?
Varistor
Fuse
Capacitor bank
Resistor ladder
Explanation - Varistors clamp a wide range of transient events.
Correct answer is: Varistor
Q.134 The primary mechanism of lightning striking a high‑voltage tower is:
Capacitive coupling
Inductive coupling
Resistive coupling
Magnetic coupling
Explanation - Lightning discharges via capacitive fields to the tower.
Correct answer is: Capacitive coupling
Q.135 Which of the following best describes a cloud‑to‑ground lightning strike?
It goes from ground to cloud
It goes from cloud to ground
It stays in the cloud
It does not involve charge transfer
Explanation - Lightning originates in the cloud and strikes the ground.
Correct answer is: It goes from cloud to ground
Q.136 Lightning strikes can cause which of the following effects on electronic equipment?
Voltage surges
Current surges
Insulation breakdown
All of the above
Explanation - All effects can damage equipment.
Correct answer is: All of the above
Q.137 Which of the following is an important design consideration for surge arresters?
Clamping voltage
Resistance
Color
Size
Explanation - Clamping voltage sets the protection threshold.
Correct answer is: Clamping voltage
Q.138 The energy of a lightning strike can reach:
10 kJ
10 MJ
10 GJ
10 TJ
Explanation - Lightning can carry megajoule energy.
Correct answer is: 10 MJ
Q.139 Lightning protection systems typically include:
Air terminals
Grounding conductors
Surge arresters
All of the above
Explanation - All components are used for effective protection.
Correct answer is: All of the above
Q.140 The main function of a spark gap is to:
Store energy
Conduct energy to ground
Limit current
Filter noise
Explanation - It provides a low‑impedance path for surges.
Correct answer is: Conduct energy to ground
Q.141 Which of the following best describes a switching surge?
Long‑duration high voltage
Short‑duration voltage spike
Constant DC offset
Low‑frequency oscillation
Explanation - Switching surges are brief transients.
Correct answer is: Short‑duration voltage spike
Q.142 The typical rise time of a lightning surge is on the order of:
10 µs
100 µs
1 ms
10 ms
Explanation - Lightning surges rise in microseconds.
Correct answer is: 10 µs
Q.143 The term 'surge impedance' refers to:
The resistance of a surge arrester
The impedance of the surge path
The impedance of the load
The impedance of the power source
Explanation - It determines how surges propagate through the system.
Correct answer is: The impedance of the surge path
Q.144 Which device is most suitable for protecting low‑voltage electronics from surges?
Metal‑oxide varistor (MOV)
Fuse
Transformer
Inductor
Explanation - MOVs clamp surges effectively at low voltage.
Correct answer is: Metal‑oxide varistor (MOV)
Q.145 Which of the following is a typical consequence of a lightning strike on a transformer?
Core saturation
Insulation breakdown
Both A and B
None of the above
Explanation - Lightning can damage both core and insulation.
Correct answer is: Both A and B
Q.146 Lightning is primarily an example of:
Electrostatic discharge
Electromagnetic induction
Electrochemical reaction
Thermal conduction
Explanation - Lightning is a discharge of static electricity.
Correct answer is: Electrostatic discharge
Q.147 Lightning-induced overvoltage can damage equipment by:
Increasing resistance
Breaking down insulation
Reducing current
Enhancing efficiency
Explanation - Surges exceed insulation voltage, causing arcing.
Correct answer is: Breaking down insulation
Q.148 Which of the following is not a typical characteristic of lightning?
High current
High voltage
Long duration
Rapid rise time
Explanation - Lightning events are very brief.
Correct answer is: Long duration
Q.149 The clamping voltage of a surge arrester is the voltage at which it:
Stops conducting
Begins conducting
Opens the circuit
Releases stored energy
Explanation - At clamping voltage the arrester starts to conduct.
Correct answer is: Begins conducting
Q.150 The most common form of lightning damage is caused by:
Voltage spikes
Current surges
Insulation breakdown
All of the above
Explanation - Surges can cause multiple failure modes.
Correct answer is: All of the above
Q.151 What is the typical peak voltage of a lightning channel?
0.5–1 kV
5–10 kV
50–100 kV
500–1 000 kV
Explanation - Lightning channels reach mega‑volt potentials.
Correct answer is: 500–1 000 kV
Q.152 Which of the following is a key parameter for a surge arrester’s effectiveness?
Clamping voltage
Surge energy absorption
Rated current
Color
Explanation - Clamping voltage defines when protection activates.
Correct answer is: Clamping voltage
Q.153 A lightning strike on a high‑voltage line can cause:
A temporary voltage surge
A permanent voltage drop
A permanent line break
All of the above
Explanation - The line typically recovers after the strike.
Correct answer is: A temporary voltage surge