Q.1 What is the primary function of a surge arrester in a high‑voltage power system?
Increase the voltage level
Reduce the current flow
Provide a low‑impedance path for surge energy
Maintain constant frequency
Explanation - A surge arrester diverts excessive transient over‑voltages to ground or a low‑impedance path, protecting downstream equipment from damage.
Correct answer is: Provide a low‑impedance path for surge energy
Q.2 Which material is commonly used for the cathode in gas‑filled surge arresters?
Silicon
Molybdenum
Graphite
Aluminium
Explanation - Graphite is chosen for its high conductivity, low sputtering tendency, and ability to withstand high temperature during surge events.
Correct answer is: Graphite
Q.3 The characteristic curve of a surge arrester is known as a _____ curve.
V-I
I-V
Z-V
Z-I
Explanation - The surge arrester’s I‑V curve shows how current rises with over‑voltage, indicating its protection capability.
Correct answer is: I-V
Q.4 What does the term 'clamping voltage' refer to in the context of a surge arrester?
The maximum voltage the arrester can withstand
The voltage at which the arrester starts conducting
The voltage after the surge is fully absorbed
The minimum operating voltage of the system
Explanation - Clamping voltage is the threshold over which the arrester switches from high to low impedance to protect equipment.
Correct answer is: The voltage at which the arrester starts conducting
Q.5 Which of the following best describes the 'breakdown voltage' of a surge arrester?
Voltage at which the arrester permanently fails
Voltage at which the arrester turns on and starts conducting
Maximum voltage the arrester can survive without damage
Minimum voltage required for arrester operation
Explanation - Breakdown voltage indicates the point where the arrester’s protective action initiates, allowing current to flow safely.
Correct answer is: Voltage at which the arrester turns on and starts conducting
Q.6 In a metal‑oxide surge arrester, the active layer is typically made of which oxide?
NiO
ZnO
TiO2
SnO2
Explanation - ZnO (zinc oxide) provides the desirable non‑linear conductivity needed for surge protection in metal‑oxide arresters.
Correct answer is: ZnO
Q.7 Which parameter is used to specify the energy absorption capability of a surge arrester?
Clamping voltage
Energy rating
Breakdown voltage
Capacitance
Explanation - Energy rating (in joules) quantifies how much surge energy the arrester can absorb before failure.
Correct answer is: Energy rating
Q.8 A surge arrester’s life is most affected by:
Ambient temperature
Number of surge events
Installation altitude
Voltage rating
Explanation - Each surge event stresses the arrester; cumulative surges degrade its material and reduce lifespan.
Correct answer is: Number of surge events
Q.9 What is the main advantage of using a gas‑filled surge arrester over a metal‑oxide arrester?
Lower cost
Higher clamping voltage
Longer life
Higher energy rating
Explanation - Gas‑filled arresters maintain a higher clamping voltage, making them suitable for very high‑voltage systems.
Correct answer is: Higher clamping voltage
Q.10 Which of the following is NOT a typical application for surge arresters?
Power transmission lines
Consumer electronics
Telecommunication cables
High‑voltage substations
Explanation - Surge arresters are used at high‑voltage levels; consumer electronics typically use smaller, built‑in protection devices.
Correct answer is: Consumer electronics
Q.11 The time delay between a surge event and the activation of a surge arrester is known as:
Rise time
Fall time
Delay time
Pulse width
Explanation - Delay time is the period before the arrester conducts after the over‑voltage threshold is exceeded.
Correct answer is: Delay time
Q.12 Which standard is most relevant for testing high‑voltage surge arresters?
IEEE 141
IEC 62271‑401
IEEE 519
ANSI C84.1
Explanation - IEC 62271‑401 specifies testing procedures for high‑voltage surge arrester devices.
Correct answer is: IEC 62271‑401
Q.13 A surge arrester’s ability to withstand repeated surges without degradation is called its:
Surge capacity
Durability
Reliability
Longevity
Explanation - Durability refers to the arrester’s resilience against multiple surge events over its operational life.
Correct answer is: Durability
Q.14 Which phenomenon is most closely associated with the 'soft break' of a gas‑filled surge arrester?
Thermal runaway
Arcing
Sputtering
Sparking
Explanation - Soft break means the device transitions from high to low impedance through a controlled arc, reducing stress on the material.
Correct answer is: Arcing
Q.15 In designing a surge protection scheme for a transformer, the arrester must be installed:
At the neutral point only
At all terminals and on the grounded side
Only at the high‑voltage side
Only at the low‑voltage side
Explanation - Arresters should protect every point of highest voltage and ground to cover all potential surge paths.
Correct answer is: At all terminals and on the grounded side
Q.16 Which type of surge is most likely to be caused by lightning?
Inductive transient
Capacitive transient
Lightning stroke
Mechanical vibration
Explanation - Lightning generates a high‑energy, high‑frequency transient that manifests as a lightning‑induced surge.
Correct answer is: Lightning stroke
Q.17 The energy absorbed by an arrester during a surge is proportional to the:
Square of the clamping voltage
Clamping voltage times current
Cube of the over‑voltage
Capacitance of the system
Explanation - Energy = ∫ V(t) I(t) dt; during a surge the product of voltage and current over time gives absorbed energy.
Correct answer is: Clamping voltage times current
Q.18 Which of these is a key design consideration for surge arresters in a 400 kV system?
Low impedance at 50 Hz
High resistance to AC
Low clamping voltage
High energy absorption capability
Explanation - High‑voltage systems experience more powerful surges, so arresters must absorb large energy levels.
Correct answer is: High energy absorption capability
Q.19 The 'breakdown voltage' of a surge arrester is measured under:
DC voltage
AC voltage
Fast pulse voltage
Sustained pulse voltage
Explanation - Breakdown is defined under a fast‑pulse (nanosecond) test to simulate lightning‑induced surges.
Correct answer is: Fast pulse voltage
Q.20 What does the term 'soft breaking' refer to in gas‑filled surge arresters?
Gradual increase of impedance
Sudden complete conduction
Controlled arc initiation
No conduction at all
Explanation - Soft breaking describes the controlled, low‑temperature arc that allows the arrester to reset after the surge.
Correct answer is: Controlled arc initiation
Q.21 Which type of surge arrester is most suitable for protecting low‑voltage DC equipment?
Gas‑filled
Metal‑oxide
Silicon avalanche
Magnetic surge arresters
Explanation - Silicon avalanche diodes offer fast response and are commonly used in DC surge protection circuits.
Correct answer is: Silicon avalanche
Q.22 The 'clamping voltage' of a surge arrester must be:
Below the normal operating voltage
Equal to the system voltage
Higher than the normal operating voltage but below the equipment rating
Higher than the equipment rating
Explanation - It protects equipment by clamping surges without interfering with normal operation.
Correct answer is: Higher than the normal operating voltage but below the equipment rating
Q.23 Which parameter indicates the arrester's capability to handle repeated surges?
Clamping voltage
Energy rating
Surge endurance
Breakdown voltage
Explanation - Surge endurance is a measure of how many surges a device can survive without failing.
Correct answer is: Surge endurance
Q.24 When a surge arrester fails, it typically shows which of the following symptoms?
Increased resistance
Decreased clamping voltage
Permanent short circuit
Complete disconnection
Explanation - Failure often reduces clamping voltage due to material degradation, allowing higher transients to reach equipment.
Correct answer is: Decreased clamping voltage
Q.25 Which of the following is a major safety hazard if surge arresters are installed incorrectly?
Over‑voltage
Under‑voltage
Short‑circuit
Ground fault
Explanation - Incorrect installation may leave high‑voltage paths unprotected, exposing equipment to surges.
Correct answer is: Over‑voltage
Q.26 In high voltage transmission lines, surge arresters are often connected to:
The neutral point
The ground rods
Both high‑voltage and low‑voltage sides
Only the high‑voltage side
Explanation - They protect all accessible points and maintain system integrity during transients.
Correct answer is: Both high‑voltage and low‑voltage sides
Q.27 Which of these is NOT a characteristic of a good surge arrester?
Fast response time
Low DC impedance
High breakdown voltage
Low energy absorption
Explanation - High energy absorption is essential; low absorption would let harmful surges pass through.
Correct answer is: Low energy absorption
Q.28 The design of a surge arrester must consider the system's:
Voltage rating only
Frequency only
Load profile only
Voltage rating, frequency, and surge characteristics
Explanation - All three aspects influence arrester selection and performance.
Correct answer is: Voltage rating, frequency, and surge characteristics
Q.29 Which test is used to verify the clamping voltage of a surge arrester?
DC voltage test
AC voltage test
Fast pulse test
Thermal test
Explanation - Fast pulse tests simulate real transient conditions and confirm clamping voltage performance.
Correct answer is: Fast pulse test
Q.30 Which of the following best describes a 'soft break' in the context of surge arresters?
Immediate discharge of stored energy
Gradual discharge through controlled arc
No discharge occurs
Arrester burns out
Explanation - Soft break refers to a controlled arc that reduces the temperature rise during surge dissipation.
Correct answer is: Gradual discharge through controlled arc
Q.31 The energy rating of a surge arrester is typically expressed in:
Volts
Amperes
Watts
Joules
Explanation - Energy rating (Joules) quantifies how much transient energy the arrester can absorb without damage.
Correct answer is: Joules
Q.32 Which of the following best explains why surge arresters are installed near the neutral point of a transformer?
To increase voltage
To provide a low‑impedance path for surges to ground
To reduce current
To regulate frequency
Explanation - The neutral point offers a direct path to earth, enabling the arrester to divert surge energy.
Correct answer is: To provide a low‑impedance path for surges to ground
Q.33 Which parameter is most critical when selecting surge arresters for a 765 kV substation?
Clamping voltage
Energy rating
Physical size
Color
Explanation - High‑voltage substations experience large surges; arrester energy rating ensures protection.
Correct answer is: Energy rating
Q.34 In which scenario would a metal‑oxide arrester be preferred over a gas‑filled arrester?
Very high voltage applications
Low‑voltage DC applications
Systems requiring long life cycles
Systems with high frequency operation
Explanation - Metal‑oxide arresters have a longer operational life and lower maintenance in many power system applications.
Correct answer is: Systems requiring long life cycles
Q.35 The main purpose of a 'surge path' in a power distribution system is to:
Reduce line losses
Provide a low‑impedance route for lightning surges
Increase voltage levels
Regulate frequency
Explanation - A surge path directs high‑energy transients safely to ground, protecting equipment.
Correct answer is: Provide a low‑impedance route for lightning surges
Q.36 Which of the following best describes the function of an air‑gap in surge arrester installation?
Increase capacitance
Reduce current flow during surges
Create a path to ground
None of the above
Explanation - The air‑gap limits the current through the arrester during a surge, protecting the device.
Correct answer is: Reduce current flow during surges
Q.37 During a surge event, the temperature inside a surge arrester rises mainly due to:
Electrical resistance
Induction
Conduction
Magnetic flux
Explanation - Resistive heating from high currents causes the surge arrester’s temperature to rise.
Correct answer is: Electrical resistance
Q.38 Which of the following is a typical failure mode for a surge arrester?
Thermal cracking
Mechanical deformation
Electrochemical corrosion
All of the above
Explanation - Thermal, mechanical, and chemical stresses can all lead to arrester failure.
Correct answer is: All of the above
Q.39 The characteristic 'breakdown voltage' for a surge arrester is defined at which time interval?
1 ms
10 μs
1 μs
100 μs
Explanation - The standard fast‑pulse test uses a 10 microsecond rise time to evaluate breakdown voltage.
Correct answer is: 10 μs
Q.40 Which of the following is a common material used for the internal cathode of metal‑oxide surge arresters?
Titanium
Molybdenum
Aluminium
Copper
Explanation - Molybdenum offers high conductivity and good sputtering resistance for the cathode.
Correct answer is: Molybdenum
Q.41 Why is it important to match the surge arrester clamping voltage to the system voltage?
To avoid over‑clamping
To ensure normal operation is not interrupted
To prevent equipment damage
All of the above
Explanation - Matching ensures proper protection, normal operation, and equipment safety.
Correct answer is: All of the above
Q.42 Which of these tests is used to evaluate the arrester’s response to high‑frequency transients?
Fast pulse test
Low frequency test
High frequency test
Thermal test
Explanation - High‑frequency tests simulate transients like switching surges that occur at higher frequencies.
Correct answer is: High frequency test
Q.43 A surge arrester that uses a metallic mesh in its construction is designed to:
Increase inductance
Provide a low‑impedance path for surge currents
Reduce capacitance
Limit DC currents
Explanation - The mesh offers a conductive path to quickly divert surges to ground.
Correct answer is: Provide a low‑impedance path for surge currents
Q.44 In a typical surge arrest system for a power transformer, the arrester is connected to:
The high‑voltage winding only
The low‑voltage winding only
Both windings and the neutral
The ground only
Explanation - Arresters protect all accessible points, including both windings and the neutral.
Correct answer is: Both windings and the neutral
Q.45 Which of the following best explains the 'soft break' behavior in gas‑filled arresters?
Rapid thermal expansion
Controlled arc formation
Immediate conduction
No conduction at all
Explanation - Soft break refers to an arc that allows the arrester to reset after a surge, limiting stress on the device.
Correct answer is: Controlled arc formation
Q.46 A surge arrester’s 'surge endurance' is defined as the maximum:
Voltage it can withstand
Energy it can absorb per event
Number of surges it can survive
Duration of each surge
Explanation - Surge endurance indicates how many transient events the arrester can handle before failure.
Correct answer is: Number of surges it can survive
Q.47 Which type of surge arrester is commonly used in high‑frequency, low‑voltage applications?
Metal‑oxide
Gas‑filled
Silicon avalanche
Magnetic surge arresters
Explanation - Silicon avalanche diodes offer fast response and are suitable for high‑frequency surges.
Correct answer is: Silicon avalanche
Q.48 Which parameter is not directly related to a surge arrester’s performance?
Clamping voltage
Breakdown voltage
Color of the enclosure
Energy rating
Explanation - Color has no effect on arrester performance; only electrical parameters matter.
Correct answer is: Color of the enclosure
Q.49 The 'energy absorption capability' of a surge arrester is typically measured under:
DC voltage
Fast pulse voltage
AC voltage
High temperature
Explanation - Fast pulse tests evaluate the arrester’s ability to absorb high‑energy surges.
Correct answer is: Fast pulse voltage
Q.50 Which of the following is a primary concern when installing surge arresters on a tower?
Wind loading
Lightning attachment points
Thermal insulation
Cable routing
Explanation - The tower must be designed to safely conduct lightning energy through the surge arrester network.
Correct answer is: Lightning attachment points
Q.51 Which of these best describes a surge arrester’s 'reset' capability?
Permanent conduction after a surge
Return to high‑impedance state after the surge
Continuous discharge of stored energy
Immediate failure after a surge
Explanation - A good arrester should revert to its normal high‑impedance state after handling a surge.
Correct answer is: Return to high‑impedance state after the surge
Q.52 In the design of high‑voltage surge protection, which of the following is NOT a typical requirement?
Low cost
High reliability
Low maintenance
High energy absorption
Explanation - While cost is important, performance and reliability often take priority in high‑voltage systems.
Correct answer is: Low cost
Q.53 Which of the following tests is performed to ensure a surge arrester’s compliance with IEC 62271‑401?
DC breakdown test
Thermal cycling test
Fast pulse test
Insulation resistance test
Explanation - The fast pulse test verifies clamping voltage and energy absorption under realistic surge conditions.
Correct answer is: Fast pulse test
Q.54 A surge arrester designed for 13.8 kV systems typically has a clamping voltage:
Above 20 kV
Between 20 kV and 30 kV
Below 10 kV
Between 30 kV and 40 kV
Explanation - Clamping voltage is chosen to stay above normal operating voltage but below equipment limits.
Correct answer is: Between 20 kV and 30 kV
Q.55 What is the main advantage of a 'soft‑break' arrester over a 'hard‑break' arrester?
Lower cost
Longer life due to reduced thermal stress
Higher clamping voltage
Higher energy absorption
Explanation - Soft‑break arresters dissipate energy with less heat, extending their service life.
Correct answer is: Longer life due to reduced thermal stress
Q.56 Which of the following statements about surge arrester placement is true?
Only the highest voltage point needs protection
All points with the highest potential should be protected
Only the neutral point needs protection
Protection is not necessary in underground cables
Explanation - Every point that can experience the highest over‑voltage must be shielded to avoid damage.
Correct answer is: All points with the highest potential should be protected
Q.57 Which of these is NOT a typical component of a surge protection system?
Surge arrester
Grounding electrode
Current transformer
Surge relay
Explanation - Current transformers are for measurement, not surge protection.
Correct answer is: Current transformer
Q.58 What is the main reason for using a gas‑filled surge arrester in a lightning protection system?
High cost
High clamping voltage
Low maintenance
None of the above
Explanation - Gas‑filled arresters can handle higher voltage surges typical of lightning strikes.
Correct answer is: High clamping voltage
Q.59 During a surge event, the surge arrester’s resistance:
Increases
Decreases
Remains constant
Oscillates randomly
Explanation - At high voltage, the arrester becomes conductive, lowering its resistance dramatically.
Correct answer is: Decreases
Q.60 The term 'surge' in high‑voltage engineering refers to:
A steady increase in voltage
A short, high‑amplitude transient voltage
A long‑duration voltage drop
A constant current flow
Explanation - Surges are brief, high‑energy voltage spikes that can damage equipment if uncontrolled.
Correct answer is: A short, high‑amplitude transient voltage
Q.61 Which type of surge arrester uses a dielectric material between the anode and cathode?
Metal‑oxide
Gas‑filled
Silicon avalanche
Magnetic
Explanation - Metal‑oxide arresters have a solid dielectric that becomes conductive during surges.
Correct answer is: Metal‑oxide
Q.62 In a high‑voltage cable, surge arresters are installed:
At the ends only
At the middle only
At every 500 meters
Only where the cable is above ground
Explanation - Regular intervals ensure continuous protection along the cable length.
Correct answer is: At every 500 meters
Q.63 Which of the following best defines the 'fast pulse test' for surge arresters?
A DC voltage test
A slow rise time voltage test
A test with a 10 µs rise time
A high‑temperature test
Explanation - Fast pulse tests mimic lightning and switching surges, using a 10 microsecond rise time.
Correct answer is: A test with a 10 µs rise time
Q.64 The 'energy rating' of an arrester is often specified as:
Joules
Watt‑hours
Volts
Amps
Explanation - Joules quantify the amount of energy the arrester can absorb safely.
Correct answer is: Joules
Q.65 Which of the following statements about 'breakdown voltage' is true?
It is the voltage at which the arrester starts conducting
It is the maximum voltage the arrester can survive
It is unrelated to surge protection
It is the minimum operating voltage
Explanation - Breakdown voltage marks the transition to low impedance during a surge.
Correct answer is: It is the voltage at which the arrester starts conducting
Q.66 Which component of a surge arrester provides the initial resistance to current during normal operation?
Cathode
Anode
Dielectric
Ground rod
Explanation - The dielectric blocks current until the voltage exceeds the breakdown threshold.
Correct answer is: Dielectric
Q.67 The 'clamping voltage' of a surge arrester is usually expressed as a multiple of:
System operating voltage
System voltage plus margin
System voltage minus margin
System voltage divided by margin
Explanation - Clamping voltage is set above normal operating voltage to avoid nuisance tripping.
Correct answer is: System voltage plus margin
Q.68 The 'surge path' network in a power distribution system is designed to:
Reduce line losses
Provide a safe route for surges to earth
Increase voltage
Control frequency
Explanation - It directs transient over‑voltages safely to ground, protecting equipment.
Correct answer is: Provide a safe route for surges to earth
Q.69 What is the typical lifetime of a metal‑oxide surge arrester under normal operating conditions?
1–2 years
5–10 years
20–30 years
50–60 years
Explanation - Under standard load, metal‑oxide arresters generally last 5–10 years before replacement.
Correct answer is: 5–10 years
Q.70 Which of these is a direct consequence of a surge arrester failure?
Lower system voltage
Increased risk of equipment damage
Reduced system frequency
Increased capacitance
Explanation - If the arrester fails, surges can reach and damage downstream equipment.
Correct answer is: Increased risk of equipment damage
Q.71 In surge protection, the term 'soft break' primarily refers to:
A sudden increase in impedance
A gradual transition from high to low impedance
The failure of the arrester
The increase in clamping voltage
Explanation - Soft break allows the arrester to reset after the surge with less thermal shock.
Correct answer is: A gradual transition from high to low impedance
Q.72 The 'energy absorption capability' of a surge arrester is largely dependent on:
Dielectric strength
Number of connected lines
Physical size only
Grounding resistance
Explanation - Dielectric properties determine how much energy can be absorbed before breakdown.
Correct answer is: Dielectric strength
Q.73 Which type of surge arrester typically requires the least maintenance?
Metal‑oxide
Gas‑filled
Silicon avalanche
All require equal maintenance
Explanation - Metal‑oxide arresters are generally robust and need minimal upkeep compared to gas‑filled units.
Correct answer is: Metal‑oxide
Q.74 The 'fast pulse test' voltage for a 345 kV arrester is:
10 kV
50 kV
200 kV
300 kV
Explanation - Fast pulse test voltage is typically around 0.6 times the system voltage.
Correct answer is: 200 kV
Q.75 What is the primary benefit of using a 'soft‑break' arrester in a high‑voltage system?
Higher clamping voltage
Longer lifespan
Lower cost
Reduced installation time
Explanation - Soft‑break devices dissipate energy with less heat, extending their service life.
Correct answer is: Longer lifespan
Q.76 In the context of surge protection, 'over‑voltage' most commonly refers to:
A voltage below the normal operating level
A voltage spike that exceeds the system rating
A steady voltage increase over months
The voltage required to power a device
Explanation - Over‑voltage transients are sudden spikes that can damage equipment.
Correct answer is: A voltage spike that exceeds the system rating
Q.77 Which of the following is NOT a standard test method for high‑voltage surge arresters?
Fast pulse test
Thermal cycling test
High frequency test
Low frequency test
Explanation - Standard tests focus on high‑frequency surges; low frequency tests are not typically used.
Correct answer is: Low frequency test
Q.78 Which of these is a typical parameter used in the design of surge arresters for transmission lines?
Line resistance
Line inductance
Expected surge energy
Load factor
Explanation - Designing for expected surge energy ensures arrester effectiveness.
Correct answer is: Expected surge energy
Q.79 A surge arrester's 'breakdown voltage' is typically:
Lower than the system voltage
Higher than the system voltage
Exactly equal to the system voltage
Independent of system voltage
Explanation - It must stay above the normal operating voltage to avoid nuisance conduction.
Correct answer is: Higher than the system voltage
Q.80 The 'surge path' network is designed to be:
High impedance
Low impedance
Neutral
Unconnected
Explanation - Low impedance paths allow surges to be safely dissipated to ground.
Correct answer is: Low impedance
Q.81 Which of the following best explains why surge arresters are commonly placed at transformer bushings?
To increase voltage
To reduce line losses
To provide a low‑impedance path to ground for surges
To control frequency
Explanation - Bushings are high‑voltage points; arresters protect them by diverting surges.
Correct answer is: To provide a low‑impedance path to ground for surges
Q.82 Which of these is a major disadvantage of gas‑filled surge arresters?
High cost
Lower clamping voltage
Short lifespan
Limited energy absorption
Explanation - Gas‑filled arresters are more expensive than metal‑oxide alternatives.
Correct answer is: High cost
Q.83 In a surge protection system, the 'breakdown' event of a surge arrester occurs at:
The system voltage
The clamping voltage
The maximum rated voltage
The minimum voltage
Explanation - Breakdown occurs when the over‑voltage exceeds the clamping voltage, triggering conduction.
Correct answer is: The clamping voltage
Q.84 What is the main purpose of a surge arrester in a power grid?
To increase current flow
To reduce voltage spikes
To regulate frequency
To store energy
Explanation - Surge arresters protect equipment by diverting transient over‑voltages to ground.
Correct answer is: To reduce voltage spikes
Q.85 The 'surge endurance' of a surge arrester is typically expressed in:
Joules
Surges
Watts
Volts
Explanation - Surge endurance is the maximum number of surges the arrester can withstand.
Correct answer is: Surges
Q.86 Which of the following best describes the 'clamping voltage' of a metal‑oxide arrester?
The maximum voltage the arrester can withstand
The voltage at which it starts to conduct
The minimum voltage for operation
The voltage drop across the arrester
Explanation - Clamping voltage is the threshold where the arrester reduces its impedance.
Correct answer is: The voltage at which it starts to conduct
Q.87 In a typical high‑voltage surge protection system, surge arresters are connected to:
Only the high‑voltage side
Only the low‑voltage side
Both high‑voltage and low‑voltage sides
Neither side
Explanation - Protection is required on all voltage levels to guard against surges.
Correct answer is: Both high‑voltage and low‑voltage sides
Q.88 Which of the following is NOT a factor in determining the size of a surge arrester?
System voltage
Expected surge energy
Ground resistance
Color of the housing
Explanation - The housing color has no effect on the arrester’s performance.
Correct answer is: Color of the housing
Q.89 The 'energy rating' of a surge arrester is expressed as:
Volts
Amps
Joules
Watt‑hours
Explanation - Energy rating indicates how much transient energy the arrester can absorb.
Correct answer is: Joules
Q.90 Which of the following best describes the 'fast pulse test' for surge arresters?
A high‑frequency AC test
A slow rise time voltage test
A test that applies a rapid voltage pulse
A thermal cycling test
Explanation - Fast pulse tests simulate lightning surges by applying a fast‑rise voltage.
Correct answer is: A test that applies a rapid voltage pulse
Q.91 The 'breakdown voltage' of a surge arrester is:
The voltage at which it starts conducting
The maximum voltage the arrester can withstand
The minimum operating voltage
The voltage drop across the arrester
Explanation - Breakdown voltage is the point where the arrester’s impedance drops dramatically.
Correct answer is: The voltage at which it starts conducting
Q.92 In surge protection, the 'surge path' network is designed to:
Reduce line losses
Provide a low‑impedance route to ground
Increase voltage
Control frequency
Explanation - It ensures surges are safely directed to earth.
Correct answer is: Provide a low‑impedance route to ground
Q.93 Which of the following is a typical failure mode for surge arresters?
Permanent short circuit
Increased clamping voltage
Low thermal resistance
Reduced impedance
Explanation - Failure can lead to a permanent low‑impedance path, compromising protection.
Correct answer is: Permanent short circuit
Q.94 The 'energy absorption capability' of a surge arrester is primarily dependent on:
Dielectric strength
System voltage
Grounding resistance
Color of the enclosure
Explanation - Dielectric properties determine how much energy can be absorbed before breakdown.
Correct answer is: Dielectric strength
Q.95 Which of these is a characteristic of a 'soft‑break' arrester?
Rapid thermal rise
Gradual transition from high to low impedance
High clamping voltage
None of the above
Explanation - Soft‑break devices reduce thermal shock by slowly transitioning during a surge.
Correct answer is: Gradual transition from high to low impedance
Q.96 The 'surge endurance' of a surge arrester is typically expressed in:
Surges
Joules
Voltage
Frequency
Explanation - It indicates the maximum number of surges the device can survive.
Correct answer is: Surges
Q.97 Which of the following best explains the function of a surge arrester in a power system?
To increase system voltage
To provide a low‑impedance path for surges to ground
To regulate frequency
To store energy for later use
Explanation - The arrester protects equipment by diverting transient over‑voltages to earth.
Correct answer is: To provide a low‑impedance path for surges to ground
Q.98 What does the term 'clamping voltage' refer to in surge arrester terminology?
The maximum voltage the arrester can withstand
The voltage at which the arrester starts conducting
The minimum operating voltage
The voltage drop across the arrester
Explanation - Clamping voltage is the threshold that triggers the arrester’s protective action.
Correct answer is: The voltage at which the arrester starts conducting
Q.99 Which type of surge arrester uses a dielectric material that becomes conductive at high voltage?
Metal‑oxide
Gas‑filled
Silicon avalanche
Magnetic
Explanation - Metal‑oxide arresters rely on a dielectric that turns conductive when over‑voltage occurs.
Correct answer is: Metal‑oxide
Q.100 In a high‑voltage system, a surge arrester’s 'breakdown voltage' is measured under:
DC voltage
Fast pulse voltage
AC voltage
High temperature
Explanation - Fast pulse tests mimic real transients and determine the breakdown threshold.
Correct answer is: Fast pulse voltage