Q.1 What is the most common method to measure a high voltage (up to 100 kV) in a laboratory setting?
Direct connection to a standard multimeter
Use of a high‑voltage probe with a voltage divider
Measuring with a low‑voltage oscilloscope only
Using a thermocouple
Explanation - A high‑voltage probe uses a precision voltage divider to step down the voltage to a safe, measurable level while providing isolation.
Correct answer is: Use of a high‑voltage probe with a voltage divider
Q.2 Which component is typically used to provide electrical isolation when measuring high voltage signals?
Ferrite core
Isolation transformer
Capacitor
Resistor divider
Explanation - An isolation transformer provides galvanic isolation between input and output, preventing high‑voltage transients from reaching measurement instruments.
Correct answer is: Isolation transformer
Q.3 A high‑voltage divider rated at 200 kV uses a 1 MΩ resistor at its top. What is the most suitable resistor value for the bottom resistor to achieve a 1000:1 division ratio?
1 kΩ
1 Ω
1 MΩ
10 kΩ
Explanation - Division ratio R_top / (R_top + R_bottom) = 200kV/200kV = 1/1000, so R_bottom ≈ 1 MΩ / 999 ≈ 1 kΩ.
Correct answer is: 1 kΩ
Q.4 Which of the following is NOT a typical cause of corona discharge in high‑voltage conductors?
Insufficient surface roughness
High ambient humidity
Excessive voltage gradient
Low current carrying capacity
Explanation - Corona is caused by high electric field gradients, surface imperfections, or humidity, not directly by low current capability.
Correct answer is: Low current carrying capacity
Q.5 What is the primary advantage of a Rogowski coil for measuring high‑current pulses?
It provides absolute current measurement without a core
It is insensitive to magnetic field orientation
It can measure DC current directly
It requires no calibration
Explanation - A Rogowski coil integrates the voltage induced by the changing magnetic field, giving a direct measurement of current with high bandwidth.
Correct answer is: It provides absolute current measurement without a core
Q.6 In a high‑current transformer (HCT), what is the purpose of the magnetic core?
To increase the voltage
To focus the electric field
To reduce the effective resistance
To concentrate magnetic flux for accurate measurement
Explanation - The core guides magnetic flux, enabling efficient coupling between primary and secondary windings for precise current sensing.
Correct answer is: To concentrate magnetic flux for accurate measurement
Q.7 Which safety class is required for equipment that may experience high‑voltage arcing up to 500 kV?
Class I
Class II
Class III
Class IV
Explanation - Class IV equipment is designed for extremely high‑voltage environments where arcing can occur at levels up to 500 kV.
Correct answer is: Class IV
Q.8 A voltage divider chain is exposed to a 100 kV spike. Which design element helps protect the measuring instrument?
Adding a shunt resistor
Using a resistive film with high ESR
Installing a gas‑filled spark gap
Increasing the number of taps in the divider
Explanation - A spark gap provides a controlled path for excess voltage, protecting sensitive components.
Correct answer is: Installing a gas‑filled spark gap
Q.9 What is the main principle behind a Hall‑effect current sensor?
Induction of voltage in a winding
Change in resistance under magnetic field
Deflection of charged particles
Generation of a voltage proportional to magnetic flux density
Explanation - A Hall‑effect sensor produces a voltage across a conductor perpendicular to the applied magnetic field, which relates to the current producing that field.
Correct answer is: Generation of a voltage proportional to magnetic flux density
Q.10 Which parameter is NOT typically monitored in a partial discharge (PD) analysis?
Amplitude of the discharge pulse
Frequency spectrum of PD signals
Thermal imaging of insulation
Time between successive discharge events
Explanation - PD analysis focuses on electrical characteristics; thermal imaging is a separate diagnostic method.
Correct answer is: Thermal imaging of insulation
Q.11 In a high‑voltage measurement setup, what does the term 'voltage coefficient of accuracy' refer to?
The percentage error at a specified reference voltage
The maximum voltage the instrument can measure
The speed at which voltage changes can be recorded
The isolation resistance between instrument and ground
Explanation - Voltage coefficient of accuracy quantifies how the measurement error varies with input voltage.
Correct answer is: The percentage error at a specified reference voltage
Q.12 Which of the following is a typical application of a high‑voltage test apparatus?
Testing transformer insulation
Measuring low‑frequency audio signals
Calibrating a standard thermometer
Generating digital logic signals
Explanation - High‑voltage testers apply controlled surges to evaluate the dielectric strength of insulation.
Correct answer is: Testing transformer insulation
Q.13 What is the typical purpose of a voltage limiter (or snubber) in high‑voltage circuits?
To increase voltage swing
To smooth out current spikes
To clamp voltage transients within safe limits
To measure current flow
Explanation - Snubbers limit voltage overshoot, protecting components from high‑voltage spikes.
Correct answer is: To clamp voltage transients within safe limits
Q.14 In high‑voltage measurement, why is the use of a differential amplifier advantageous?
It reduces the need for shielding
It eliminates common‑mode noise between two high‑voltage nodes
It increases the input impedance to infinity
It allows direct measurement of absolute voltage
Explanation - Differential amplifiers amplify the voltage difference while rejecting common‑mode signals, essential for accurate HV measurements.
Correct answer is: It eliminates common‑mode noise between two high‑voltage nodes
Q.15 Which of the following is a safety precaution when handling a high‑voltage test rig?
Work in a dry environment
Wear conductive gloves for better grounding
Ignore the isolation rating of cables
Use metal tools to avoid sparks
Explanation - Low humidity reduces the risk of arcing; conductive gloves can create a fault path, and metal tools increase spark risk.
Correct answer is: Work in a dry environment
Q.16 What is the key function of a high‑voltage probe’s input impedance?
To store charge during measurement
To provide a reference ground
To isolate the measurement circuit and minimize loading
To amplify the input signal
Explanation - High input impedance ensures that the probe does not significantly load the circuit under test.
Correct answer is: To isolate the measurement circuit and minimize loading
Q.17 In a voltage divider, what determines the voltage division ratio?
Only the total resistance
Only the input voltage
The ratio of individual resistances
The temperature of resistors
Explanation - Voltage division depends on the relative sizes of the resistors, not on the absolute values or temperature (though temperature effects exist).
Correct answer is: The ratio of individual resistances
Q.18 Which material is commonly used in high‑voltage insulators for power transmission lines?
Glass
Copper
Aluminium
Steel
Explanation - Glass insulators provide high dielectric strength, low weight, and environmental resistance.
Correct answer is: Glass
Q.19 What does the IEC 60076 standard address?
High‑voltage cable installation
Electrical safety for households
High‑voltage switchgear and circuit breakers
Low‑voltage power distribution
Explanation - IEC 60076 covers the design and testing of high‑voltage switchgear and circuit breakers.
Correct answer is: High‑voltage switchgear and circuit breakers
Q.20 Which of the following is NOT a type of spark gap used for high‑voltage protection?
Air spark gap
Gas‑filled spark gap
Vacuum spark gap
Resistor‑based spark gap
Explanation - Resistors are not spark gaps; they dissipate power as heat rather than allow a controlled arc.
Correct answer is: Resistor‑based spark gap
Q.21 Why is a series resistor added before a high‑voltage probe?
To increase the measured voltage
To provide additional isolation and limit current
To reduce the probe’s input impedance
To calibrate the probe automatically
Explanation - The series resistor limits the current that can flow into the probe, protecting it from surges.
Correct answer is: To provide additional isolation and limit current
Q.22 In a high‑voltage testing rig, what is the purpose of a surge‑voltage generator?
To produce low‑frequency signals
To test the mechanical strength of conductors
To simulate lightning‑induced surges for insulation testing
To calibrate meters for DC voltage
Explanation - Surge generators mimic the high‑current, high‑voltage transients of lightning strikes.
Correct answer is: To simulate lightning‑induced surges for insulation testing
Q.23 Which parameter is crucial for selecting a resistor in a high‑voltage divider?
Its nominal resistance value only
Its temperature coefficient of resistance
Its physical size
Its power rating and voltage rating
Explanation - Resistors must tolerate the voltage across them and dissipate the heat generated without failure.
Correct answer is: Its power rating and voltage rating
Q.24 What is the primary measurement challenge when detecting high‑frequency partial discharge?
Low signal amplitude and high bandwidth requirements
High noise from power lines
Difficulty in mounting the probe
The need for a large measurement area
Explanation - PD pulses are nanosecond in duration and low in amplitude, requiring sensitive, wide‑bandwidth instrumentation.
Correct answer is: Low signal amplitude and high bandwidth requirements
Q.25 Which of the following best describes a 'high‑voltage transformer'?
A transformer with a very low secondary voltage
A transformer that can handle voltages in the kilovolt to megavolt range
A transformer with a core made of copper
A transformer used only for AC to DC conversion
Explanation - High‑voltage transformers are designed for use in power transmission and industrial equipment.
Correct answer is: A transformer that can handle voltages in the kilovolt to megavolt range
Q.26 Which safety device should be used to protect personnel from accidental contact with live high‑voltage conductors?
Arc‑flash suit
Ground‑fault circuit interrupter (GFCI)
Thermocouple
Low‑voltage battery
Explanation - Arc‑flash suits protect against burns from arc flashes during high‑voltage incidents.
Correct answer is: Arc‑flash suit
Q.27 What does 'high‑frequency measurement' of voltage primarily involve?
Using a standard analog meter
Using a digital oscilloscope with high‑bandwidth probes
Using a thermometer
Using a mechanical voltmeter
Explanation - High‑frequency voltages require bandwidth‑capable equipment for accurate capture.
Correct answer is: Using a digital oscilloscope with high‑bandwidth probes
Q.28 In a current‑transformer (CT) circuit, what is the purpose of the burden resistor?
To provide a path for neutral current
To limit the secondary current to safe levels for measuring instruments
To increase the current in the primary winding
To stabilize the temperature of the transformer
Explanation - The burden resistor sets the load on the secondary and defines the output voltage for the meter.
Correct answer is: To limit the secondary current to safe levels for measuring instruments
Q.29 Which of these is a disadvantage of using a metal‑oxide varistor (MOV) for high‑voltage suppression?
It has a high leakage current at low voltage
It can only be used for DC applications
It is very expensive per unit
It cannot handle repetitive surges
Explanation - MOVs have a measurable leakage current which can affect sensitive measurements.
Correct answer is: It has a high leakage current at low voltage
Q.30 What is the function of a 'guard ring' in high‑voltage probe design?
To improve mechanical strength
To shield the probe from magnetic fields
To reduce stray capacitance and leakage currents
To increase the input resistance
Explanation - Guard rings provide a controlled path for leakage, improving accuracy.
Correct answer is: To reduce stray capacitance and leakage currents
Q.31 Which parameter is NOT measured by a typical high‑voltage data acquisition system?
Voltage waveform
Current waveform
Mechanical stress
Temperature of the measuring device
Explanation - Electrical measurement systems record electrical signals; mechanical stress requires separate sensors.
Correct answer is: Mechanical stress
Q.32 Why is a high‑voltage measurement system often designed with a differential input rather than single‑ended?
Because it can handle higher currents
To increase the input impedance to infinite
To reject common‑mode noise and increase accuracy
It simplifies calibration procedures
Explanation - Differential input removes shared noise, critical for high‑voltage environments.
Correct answer is: To reject common‑mode noise and increase accuracy
Q.33 Which component is essential for protecting a high‑voltage probe from dielectric breakdown?
A series capacitor
A gas‑filled spark gap
An inductive choke
A voltage divider with a high ESR resistor
Explanation - Gas‑filled spark gaps safely redirect excess voltage, preventing breakdown.
Correct answer is: A gas‑filled spark gap
Q.34 In a high‑voltage testing facility, what does the term 'breakdown voltage' refer to?
The maximum current the system can carry
The voltage at which insulation fails and arc forms
The voltage at which a spark gap triggers
The maximum temperature the system can handle
Explanation - Breakdown voltage is the threshold where dielectric material can no longer withstand the electric field.
Correct answer is: The voltage at which insulation fails and arc forms
Q.35 What is the main advantage of using a 'floating' measurement system?
It eliminates the need for shielding
It allows measurement without a return path
It provides galvanic isolation from ground, reducing risk of shock
It increases measurement bandwidth
Explanation - A floating system isolates the measurement path from the mains, enhancing safety.
Correct answer is: It provides galvanic isolation from ground, reducing risk of shock
Q.36 Which of the following is a common error source when using a high‑voltage divider chain?
The resistors are too small in value
The chain is over‑tuned for frequency response
The resistors’ tolerance and temperature coefficient
The resistors are placed too close together
Explanation - Resistor tolerances and temperature drift directly affect the accuracy of the division ratio.
Correct answer is: The resistors’ tolerance and temperature coefficient
Q.37 Which of these is an essential safety feature of a high‑voltage test cabinet?
An open side for easy access
An unprotected ventilation system
A lockable, grounded enclosure with interlocked doors
A built‑in heater
Explanation - Interlocked doors prevent accidental access while the test is running.
Correct answer is: A lockable, grounded enclosure with interlocked doors
Q.38 In the context of high‑voltage measurement, what does the 'time constant' of a voltage divider refer to?
The product of its resistance and capacitance
The maximum input voltage it can handle
The resistance ratio between its taps
The frequency response of the measurement instrument
Explanation - The RC time constant determines the response speed and bandwidth of the divider network.
Correct answer is: The product of its resistance and capacitance
Q.39 What is a primary benefit of using a 'high‑voltage probe' versus a standard oscilloscope probe?
It can measure DC voltage directly
It has higher input resistance and built‑in isolation
It eliminates the need for shielding cables
It can handle any waveform without filtering
Explanation - High‑voltage probes are designed to handle large potentials safely.
Correct answer is: It has higher input resistance and built‑in isolation
Q.40 Which of the following is a typical characteristic of a 'spark gap' used in high‑voltage circuits?
It is a passive resistor with low voltage drop
It provides a fixed voltage threshold for triggering arcing
It acts as a transformer
It can be used to step down voltage
Explanation - Spark gaps are designed to ignite at a predetermined breakdown voltage.
Correct answer is: It provides a fixed voltage threshold for triggering arcing
Q.41 Which measurement device is suitable for capturing short‑duration voltage spikes in a high‑voltage environment?
Standard analog voltmeter
High‑frequency digital oscilloscope
Thermocouple
Mechanical ammeter
Explanation - Oscilloscopes with high sampling rates are required to resolve nanosecond transients.
Correct answer is: High‑frequency digital oscilloscope
Q.42 A 'Rogowski coil' measures current by detecting the magnetic field. Which law does it rely on?
Ohm's Law
Faraday's Law of Induction
Kirchhoff's Voltage Law
Coulomb's Law
Explanation - The coil converts time‑varying magnetic flux into voltage, as described by Faraday’s Law.
Correct answer is: Faraday's Law of Induction
Q.43 Which of the following is a common method to calibrate a high‑voltage probe?
Using a precision low‑voltage standard
Applying a known high‑voltage step and measuring output
Measuring the temperature coefficient
Using a mechanical lever
Explanation - Calibration involves applying a known reference voltage and adjusting the probe response.
Correct answer is: Applying a known high‑voltage step and measuring output
Q.44 What is the typical purpose of a 'high‑voltage relay' in a test circuit?
To provide isolation between low and high voltage circuits
To increase the voltage output
To serve as a primary measurement instrument
To reduce the current flowing through the test equipment
Explanation - High‑voltage relays switch high‑voltage circuits safely without direct electrical contact.
Correct answer is: To provide isolation between low and high voltage circuits
Q.45 Which component is typically used to terminate a high‑voltage transmission line at its end?
Shunt resistor
High‑voltage termination resistor
Capacitor
Inductor
Explanation - Terminating resistors match the line impedance, preventing reflections and arcing.
Correct answer is: High‑voltage termination resistor
Q.46 Which of the following is an example of a 'current‑sense resistor' used in high‑current measurement?
A 0.1 Ω, 10 W shunt resistor
A 1 MΩ precision resistor
A 100 kΩ resistor divider
A 50 Ω termination resistor
Explanation - A low‑value, high‑power resistor provides a measurable voltage drop proportional to the current.
Correct answer is: A 0.1 Ω, 10 W shunt resistor
Q.47 Which of the following safety devices is used to prevent over‑voltage transients from reaching measurement equipment?
Surge protector
Thermocouple
Resistive load
Capacitor bank
Explanation - Surge protectors clamp high voltage spikes, shielding sensitive instruments.
Correct answer is: Surge protector
Q.48 In high‑voltage measurement, why is the use of a 'shielded cable' essential?
It increases the cable’s voltage rating
It prevents external electromagnetic interference
It reduces the cable’s mechanical strength
It makes the cable more flexible
Explanation - Shielding keeps external noise from corrupting the measured signal.
Correct answer is: It prevents external electromagnetic interference
Q.49 A high‑voltage measurement system is designed for up to 500 kV. Which insulation class is required for the cables?
Class I
Class II
Class III
Class IV
Explanation - Class IV insulation can withstand extremely high voltages and is used for HV systems.
Correct answer is: Class IV
Q.50 What is a key characteristic of a 'metal‑oxide varistor (MOV)' used in high‑voltage suppression?
It has a constant resistance at all voltages
It acts as a capacitor at low voltage
It rapidly changes resistance above a threshold voltage
It is a linear resistor
Explanation - MOVs become highly conductive when the applied voltage exceeds their breakdown threshold.
Correct answer is: It rapidly changes resistance above a threshold voltage
Q.51 Which of the following is a typical measurement method for high‑frequency currents?
Hall‑effect sensor
Shunt resistor and differential amplifier
Potentiometer
Mechanical ammeter
Explanation - Shunt + differential amplifier can capture fast current variations when properly designed.
Correct answer is: Shunt resistor and differential amplifier
Q.52 What does the term 'voltage divider ratio' describe?
The ratio of the output voltage to the input voltage
The ratio of the current in the two branches
The temperature coefficient of the resistors
The maximum voltage the divider can withstand
Explanation - It quantifies how much of the input voltage appears across the divider’s output.
Correct answer is: The ratio of the output voltage to the input voltage
Q.53 Which of the following is NOT typically used as an insulating material in high‑voltage cables?
Cross‑linked polyethylene (XLPE)
EPR (ethylene propylene rubber)
PVC (polyvinyl chloride)
Copper
Explanation - Copper is conductive; it is used for conductors, not insulation.
Correct answer is: Copper
Q.54 In a high‑voltage testing rig, the surge‑voltage generator is typically characterized by its
Peak voltage, pulse width, rise time, and energy
DC voltage output only
Capacitive coupling
Mechanical displacement
Explanation - Surge generators must specify these parameters to match real‑world lightning transients.
Correct answer is: Peak voltage, pulse width, rise time, and energy
Q.55 Which of the following measurement instruments can directly measure high‑frequency voltage transients?
Standard DMM
High‑speed digital oscilloscope
Analog voltmeter
Thermistor
Explanation - Only high‑speed oscilloscopes have the bandwidth required for transients.
Correct answer is: High‑speed digital oscilloscope
Q.56 Which type of probe is used to measure the magnetic field generated by a high‑current conductor?
Electric field probe
Hall‑effect probe
Thermocouple probe
Voltage probe
Explanation - Hall probes sense magnetic fields and are commonly used for current measurement.
Correct answer is: Hall‑effect probe
Q.57 In the context of high‑voltage measurement, what is a 'burden' resistor?
A resistor used to reduce the voltage across the probe
A resistor placed across the measurement instrument to define its loading
A resistor that limits current in the primary winding
A resistor that dissipates heat from the probe
Explanation - Burden resistors set the load on the secondary of a current transformer.
Correct answer is: A resistor placed across the measurement instrument to define its loading
Q.58 Which component is typically used to provide a return path for high‑voltage measurement circuits?
Ground electrode
Neutral conductor
High‑voltage transformer secondary
All of the above
Explanation - A return path is essential for completing the circuit and is achieved via any of these options.
Correct answer is: All of the above
Q.59 What is a common cause of measurement drift in high‑voltage resistive dividers?
Mechanical vibration
Temperature changes affecting resistor values
Air pressure variations
Light exposure
Explanation - Resistors’ values vary with temperature, affecting accuracy over time.
Correct answer is: Temperature changes affecting resistor values
Q.60 Which of the following is a typical feature of a 'high‑voltage oscilloscope probe'?
Input resistance of 1 kΩ
Built‑in voltage divider with high isolation
No shielding
Direct DC coupling only
Explanation - High‑voltage probes include isolation and a precision divider for safe measurement.
Correct answer is: Built‑in voltage divider with high isolation
Q.61 What is the main function of an 'arcing test' in high‑voltage engineering?
To test mechanical strength of conductors
To evaluate the insulation’s ability to withstand arcing
To measure the exact breakdown voltage
To calibrate measurement instruments
Explanation - An arcing test intentionally applies a high‑voltage arc to assess insulation durability.
Correct answer is: To evaluate the insulation’s ability to withstand arcing
Q.62 Which of the following best describes a 'high‑frequency current probe'?
A probe that measures current in DC only
A probe that uses a magnetic core for low‑frequency currents
A probe that uses a Rogowski coil or Hall sensor for rapid current changes
A probe that directly measures voltage
Explanation - High‑frequency probes rely on magnetic field sensing for fast currents.
Correct answer is: A probe that uses a Rogowski coil or Hall sensor for rapid current changes
Q.63 Which of the following is a key design consideration for high‑voltage measurement cabling?
Low dielectric constant to reduce capacitance
High current capacity only
High mechanical flexibility only
Low resistance regardless of insulation
Explanation - Low dielectric constant reduces stray capacitance, improving measurement accuracy.
Correct answer is: Low dielectric constant to reduce capacitance
Q.64 Which of the following statements is true regarding a 'high‑voltage isolation transformer'?
It offers no protection against voltage transients
It allows high voltage to be stepped up or down while maintaining isolation
It is used only for DC applications
It can be directly connected to mains without protection
Explanation - Isolation transformers isolate the primary and secondary electrically while providing voltage transformation.
Correct answer is: It allows high voltage to be stepped up or down while maintaining isolation
Q.65 Which of the following is a typical method to detect a breakdown event in a high‑voltage test?
Observing the color of the conductor
Measuring the drop in the supply voltage
Listening to a high‑frequency sound
Using a pressure sensor
Explanation - A breakdown often causes a sudden voltage drop, which can be monitored with a high‑speed instrument.
Correct answer is: Measuring the drop in the supply voltage
Q.66 In high‑voltage measurement, why are 'guarding' techniques employed?
To increase the measurement bandwidth
To reduce stray capacitance and leakage currents
To lower the cost of instrumentation
To improve the visual appearance of equipment
Explanation - Guarding provides a controlled path for leakage, improving accuracy and safety.
Correct answer is: To reduce stray capacitance and leakage currents
Q.67 What is the function of a 'transient voltage surge suppressor (TVSS)'?
To increase the peak voltage of the system
To limit transient voltage surges to a safe level
To transform voltage levels
To measure the voltage accurately
Explanation - TVSS devices clamp excessive voltage, protecting downstream equipment.
Correct answer is: To limit transient voltage surges to a safe level
Q.68 Which of the following best describes a 'high‑voltage probe' input impedance?
10 kΩ
1 MΩ
10 GΩ or higher
100 Ω
Explanation - High‑voltage probes require extremely high impedance to avoid loading the circuit.
Correct answer is: 10 GΩ or higher
Q.69 Which measurement method uses a 'shunt resistor' to determine current?
Capacitive coupling
Resistive division with voltage measurement across the resistor
Optical isolation
Mechanical lever
Explanation - Current is derived from the voltage drop across a known resistance using Ohm’s law.
Correct answer is: Resistive division with voltage measurement across the resistor
Q.70 What does 'high‑voltage test bench' typically refer to?
A bench that provides low‑voltage DC for hobby projects
A setup that can generate and measure high voltages for equipment testing
A portable measurement instrument for AC only
A device used for mechanical testing of conductors
Explanation - High‑voltage test benches are used to validate insulation, surge tolerance, and more.
Correct answer is: A setup that can generate and measure high voltages for equipment testing
Q.71 Which of the following is NOT a typical function of a 'voltage transformer' in high‑voltage measurements?
Providing a reference ground
Isolating the measurement system from the high‑voltage source
Stepping up voltage for measurement
Stepping down voltage to a safe level
Explanation - Voltage transformers are used primarily for isolation and stepping down, not up.
Correct answer is: Stepping up voltage for measurement
Q.72 Which of the following is a common cause for voltage measurement errors at high frequencies?
Resistor tolerance
Capacitive coupling between probe and ground
Temperature changes
Mechanical wear
Explanation - Capacitance introduces phase shifts and amplitude errors at high frequencies.
Correct answer is: Capacitive coupling between probe and ground
Q.73 Which component is used to provide a high‑frequency current measurement for power electronics?
Hall‑effect sensor
Rogowski coil
Thermocouple
Resistor divider
Explanation - Rogowski coils are designed for high‑bandwidth, high‑frequency current measurements.
Correct answer is: Rogowski coil
Q.74 The 'voltage coefficient of accuracy' is typically expressed as a percentage. What does a coefficient of 0.5% at 100 kV mean?
The measurement error is ±0.5 kV at 100 kV
The measurement error is ±0.5 V at 100 kV
The voltage divider has a 0.5% tolerance
The instrument can measure up to 0.5% of 100 kV
Explanation - A coefficient of 0.5% indicates an absolute error of 0.5% of the input voltage.
Correct answer is: The measurement error is ±0.5 kV at 100 kV
Q.75 Which safety device is crucial for detecting ground faults in high‑voltage circuits?
Ground‑fault circuit interrupter (GFCI)
Thermocouple
Voltage divider
Isolation transformer
Explanation - A GFCI detects imbalance and trips the circuit to prevent electric shock.
Correct answer is: Ground‑fault circuit interrupter (GFCI)
Q.76 In a high‑voltage measurement, which of the following is a typical use of a 'burden resistor'?
To limit the voltage across a shunt resistor
To set the output voltage of a current transformer
To provide mechanical support
To increase the current flowing through the sensor
Explanation - The burden resistor defines the secondary voltage for a CT.
Correct answer is: To set the output voltage of a current transformer
Q.77 What is the primary function of a 'gas‑filled spark gap' in high‑voltage circuits?
To increase the resistance of the circuit
To provide a controlled arcing path when a certain voltage is exceeded
To measure voltage directly
To step down voltage
Explanation - Gas‑filled spark gaps act as voltage limiters by allowing current to flow when breakdown occurs.
Correct answer is: To provide a controlled arcing path when a certain voltage is exceeded
Q.78 Which of the following measurement tools is commonly used to determine the dielectric strength of an insulating material?
High‑voltage test generator
Low‑frequency oscilloscope
Mechanical stress tester
Capacitive meter
Explanation - A high‑voltage generator applies controlled surges to test insulation.
Correct answer is: High‑voltage test generator
Q.79 What is the effect of temperature on a high‑voltage resistor used in a voltage divider?
No effect
It changes the resistance value, altering the division ratio
It reduces the insulation resistance
It increases the voltage rating
Explanation - Temperature coefficients cause drift in resistance values, impacting accuracy.
Correct answer is: It changes the resistance value, altering the division ratio
Q.80 Which of the following is an advantage of using a 'floating' high‑voltage measurement system?
No need for grounding
Eliminates the need for shielding
Provides galvanic isolation and reduces shock risk
Allows for higher measurement bandwidth
Explanation - A floating system isolates measurement circuits from ground.
Correct answer is: Provides galvanic isolation and reduces shock risk
Q.81 Which device is used to measure the phase difference between high‑voltage and current waveforms?
Phase meter
Capacitive coupler
Thermocouple
Resistor divider
Explanation - Phase meters detect the relative phase between voltage and current signals.
Correct answer is: Phase meter
Q.82 What is the main purpose of a 'high‑voltage shunt resistor'?
To reduce voltage across the load
To provide a low‑impedance path for current measurement
To step down voltage to a measurable level
To act as a current transformer
Explanation - The shunt resistor creates a small voltage drop proportional to the current.
Correct answer is: To provide a low‑impedance path for current measurement
Q.83 Which safety class is appropriate for a 600 kV transmission line?
Class I
Class II
Class III
Class IV
Explanation - Class IV insulation is designed for extremely high voltages such as 600 kV.
Correct answer is: Class IV
Q.84 In a high‑voltage test system, why is a 'low‑leakage current' path important?
To reduce noise in measurement
To ensure safety by limiting stray currents
To increase the measurement bandwidth
To improve mechanical stability
Explanation - Low leakage currents reduce the risk of electric shock and measurement errors.
Correct answer is: To ensure safety by limiting stray currents
Q.85 Which of the following is a typical high‑voltage measurement configuration for AC mains?
Direct connection to the meter
Use of a potential transformer and isolation transformer
Use of a current shunt only
Use of a DC voltage divider
Explanation - Transformers provide isolation and stepping down of AC mains for measurement.
Correct answer is: Use of a potential transformer and isolation transformer
Q.86 What is the key difference between a 'voltage divider' and a 'potential divider' in high‑voltage measurement?
The former uses resistors, the latter uses capacitors
There is no difference; they are the same
The potential divider provides a safe reference potential for measurement
The potential divider is only used for DC
Explanation - Potential dividers are designed with isolation and safety in mind.
Correct answer is: The potential divider provides a safe reference potential for measurement
Q.87 Which of the following best describes the purpose of a 'surge arrestor' in a high‑voltage system?
To amplify high‑frequency signals
To clamp excessive voltage spikes to a safe level
To provide mechanical support
To step down voltage for measurement
Explanation - Surge arrestors protect equipment by limiting transient voltages.
Correct answer is: To clamp excessive voltage spikes to a safe level
Q.88 Which of the following is a key parameter of a 'high‑voltage probe' that must be calibrated?
Input impedance
Voltage ratio
Temperature coefficient
All of the above
Explanation - Probe accuracy depends on impedance, ratio, and temperature behavior.
Correct answer is: All of the above
Q.89 Which of the following is NOT a typical characteristic of a 'high‑voltage transformer'?
High insulation resistance
Large core size to reduce saturation
Low voltage rating
Ability to handle high currents
Explanation - High‑voltage transformers are designed for high voltage, not low voltage.
Correct answer is: Low voltage rating
Q.90 What is the purpose of a 'ground‑plane' in a high‑voltage test setup?
To provide a reference for all measurements
To act as a heat sink
To increase the system's capacitance
To eliminate the need for isolation
Explanation - Ground planes serve as a stable potential reference for accurate measurements.
Correct answer is: To provide a reference for all measurements
Q.91 Which type of measurement is most appropriate for detecting nanosecond partial discharge events?
Low‑frequency oscilloscope
High‑bandwidth oscilloscope with specialized PD probe
Standard DMM
Mechanical sensor
Explanation - Nanosecond PD signals require high sampling rates and specialized probes.
Correct answer is: High‑bandwidth oscilloscope with specialized PD probe
Q.92 Which component in a high‑voltage measurement system helps to reduce electromagnetic interference?
Unshielded cable
Ferrite bead
High‑temperature resistor
Metal‑oxide varistor
Explanation - Ferrite beads suppress high‑frequency noise in cables.
Correct answer is: Ferrite bead
Q.93 In a high‑voltage test, the 'breakdown voltage' is measured as 350 kV. What does this mean?
The circuit can handle 350 kV continuously
At 350 kV, the insulation fails and arcing occurs
The maximum current at 350 kV is 350 A
The system operates at 350 V only
Explanation - Breakdown voltage indicates the threshold for insulation failure.
Correct answer is: At 350 kV, the insulation fails and arcing occurs
Q.94 Which of the following is a typical feature of a 'high‑voltage oscilloscope probe'?
Input resistance of 10 kΩ
Built‑in isolation transformer
No shielding
Direct DC coupling only
Explanation - High‑voltage probes incorporate isolation transformers for safety.
Correct answer is: Built‑in isolation transformer
Q.95 What is the primary advantage of using a 'high‑voltage shunt resistor' over a current transformer?
Higher bandwidth for rapid signals
Lower cost and simpler installation
Greater isolation from high voltage
Higher accuracy at low frequencies
Explanation - Shunt resistors are inexpensive and easy to install but have lower bandwidth than CTs.
Correct answer is: Lower cost and simpler installation
Q.96 Which of the following is a typical safety requirement for a high‑voltage laboratory?
No protective gear required
Use of grounded gloves only
Strict isolation of test equipment and clear signage
Allowing work in open air
Explanation - Safety in HV labs demands isolation, signage, and protective gear.
Correct answer is: Strict isolation of test equipment and clear signage
Q.97 What role does a 'voltage probe’s' guard ring play?
To increase the input capacitance
To provide a low‑impedance path for leakage current
To reduce stray capacitance and improve isolation
To measure the current
Explanation - Guard rings help maintain isolation and reduce leakage paths.
Correct answer is: To reduce stray capacitance and improve isolation
Q.98 Which of the following is a typical application for a 'current transformer'?
Measuring DC current only
Measuring high‑frequency AC current only
Measuring alternating current in power systems
Measuring voltage across a resistor
Explanation - CTs are used to sense AC current for monitoring and protection.
Correct answer is: Measuring alternating current in power systems
Q.99 Which of the following best describes a 'high‑voltage spark gap'?
A resistor used for voltage stepping
A device that triggers arcing when a threshold voltage is reached
An inductive choke for high frequency
A type of transformer
Explanation - Spark gaps break down at a predetermined voltage, allowing current to flow.
Correct answer is: A device that triggers arcing when a threshold voltage is reached
Q.100 Which component is typically used to measure high‑voltage pulse rise time?
High‑speed oscilloscope with a high‑voltage probe
Standard DMM
Thermocouple
Capacitor
Explanation - Accurate rise‑time measurements require high bandwidth equipment.
Correct answer is: High‑speed oscilloscope with a high‑voltage probe
Q.101 What is the main purpose of a 'high‑frequency current probe' in power electronics?
To step down voltage
To measure fast transients in current
To provide isolation for DC circuits
To measure temperature
Explanation - High‑frequency probes capture rapid changes in current for analysis.
Correct answer is: To measure fast transients in current
Q.102 Which of the following is a typical method for measuring high‑frequency voltage spikes?
Using a standard analog meter
Using a digital oscilloscope with a high‑bandwidth probe
Using a mechanical ammeter
Using a thermometer
Explanation - High‑frequency spikes require instruments capable of high sampling rates.
Correct answer is: Using a digital oscilloscope with a high‑bandwidth probe
Q.103 Which of the following is NOT a characteristic of a 'high‑voltage isolation transformer'?
Provides voltage isolation
Stepping up voltage only
Can handle high power
Has high insulation resistance
Explanation - Isolation transformers can step up or step down voltages while maintaining isolation.
Correct answer is: Stepping up voltage only
Q.104 What is a common test for evaluating partial discharge in high‑voltage equipment?
Visual inspection
High‑frequency impedance measurement
Partial discharge measurement with a PD detector
Thermal imaging
Explanation - PD detectors capture the electrical signatures of partial discharges.
Correct answer is: Partial discharge measurement with a PD detector
Q.105 Which of the following best describes the purpose of a 'voltage probe's' input capacitance?
To store charge for measurement
To limit the probe’s bandwidth
To provide isolation
To increase the input impedance
Explanation - Input capacitance, together with resistance, forms an RC filter limiting bandwidth.
Correct answer is: To limit the probe’s bandwidth
Q.106 In high‑voltage measurement, which of the following is a typical use of a 'burden resistor'?
To provide a low‑impedance path for current measurement
To define the output voltage of a current transformer
To increase the voltage across the probe
To step down voltage to a safe level
Explanation - The burden resistor sets the load on the CT secondary and defines the measured voltage.
Correct answer is: To define the output voltage of a current transformer
Q.107 Which of the following is a key requirement for a high‑voltage test cabinet?
Open design for easy access
Grounded enclosure with interlocked doors
No ventilation required
Low insulation rating
Explanation - Interlocked, grounded enclosures protect operators during HV tests.
Correct answer is: Grounded enclosure with interlocked doors
Q.108 Which of the following is a common method for measuring high‑voltage pulses in power electronics?
Using a standard multimeter
Using a high‑speed oscilloscope and a high‑voltage probe
Using a mechanical ammeter
Using a thermocouple
Explanation - High‑speed oscilloscope + probe captures fast voltage transients.
Correct answer is: Using a high‑speed oscilloscope and a high‑voltage probe
Q.109 Which component is used to provide a controlled path for current during a surge in a high‑voltage system?
Capacitor
Resistor
Surge arrestor (e.g., TVS)
Inductor
Explanation - Surge arrestors clamp over‑voltage spikes to protect equipment.
Correct answer is: Surge arrestor (e.g., TVS)
Q.110 What is the primary advantage of using a 'high‑voltage isolation transformer' for measurement?
To provide high bandwidth
To step up the voltage
To isolate the measurement from the mains
To reduce the voltage
Explanation - Isolation transformers keep the measurement system electrically separate from mains.
Correct answer is: To isolate the measurement from the mains
Q.111 Which of the following is a common technique to reduce stray capacitance in a high‑voltage measurement chain?
Using thick cables
Adding ferrite beads
Increasing the number of turns in the transformer
Using low‑temperature resistors
Explanation - Ferrite beads suppress high‑frequency noise and reduce stray capacitance.
Correct answer is: Adding ferrite beads
Q.112 What is the main role of a 'high‑voltage probe' input resistance?
To lower the input impedance
To provide high impedance, minimizing loading effects
To increase the probe’s bandwidth
To reduce the probe's cost
Explanation - High impedance ensures the probe does not alter the measured voltage.
Correct answer is: To provide high impedance, minimizing loading effects
Q.113 Which of the following is an important consideration when selecting a resistive voltage divider for 500 kV measurement?
Resistor tolerance only
Power rating and voltage rating of the resistors
Capacitance of the resistors
Physical color of the resistors
Explanation - Resistors must handle both the voltage across them and the power dissipation.
Correct answer is: Power rating and voltage rating of the resistors
Q.114 What does the 'time constant' of a voltage divider influence?
Maximum voltage it can handle
Bandwidth and response time of the divider
Temperature coefficient of resistors
Physical size of the divider
Explanation - Time constant (RC) determines how quickly the divider reacts to voltage changes.
Correct answer is: Bandwidth and response time of the divider
Q.115 Which of the following is NOT a typical use of a 'high‑frequency current probe'?
Measuring fast current spikes in power converters
Measuring DC current in a battery
Monitoring transient currents in motor drives
Diagnosing EMI sources
Explanation - High‑frequency probes are designed for AC and transients, not DC.
Correct answer is: Measuring DC current in a battery
Q.116 Which safety device is designed to detect and disconnect ground faults in high‑voltage circuits?
Ground‑fault circuit interrupter (GFCI)
High‑voltage transformer
Rogowski coil
Isolation resistor
Explanation - GFCI monitors imbalance and trips the circuit to prevent shock.
Correct answer is: Ground‑fault circuit interrupter (GFCI)
Q.117 What is the most common method to calibrate a high‑voltage probe?
By applying a known DC voltage only
By measuring the temperature coefficient
By applying a known high‑voltage step and measuring the output
By using a mechanical lever system
Explanation - Calibration involves applying a reference voltage and adjusting probe response.
Correct answer is: By applying a known high‑voltage step and measuring the output
Q.118 Which of the following is a typical use for a 'high‑voltage surge generator'?
Measuring DC current
Simulating lightning‑induced surges for insulation testing
Calibrating a digital multimeter
Generating low‑frequency AC signals
Explanation - Surge generators produce high‑voltage, short‑duration pulses resembling lightning.
Correct answer is: Simulating lightning‑induced surges for insulation testing
Q.119 Which of the following best describes a 'high‑voltage shunt resistor'?
A high‑impedance resistor used to step down voltage
A low‑value resistor providing a measurable voltage drop proportional to current
A capacitor used in high‑voltage circuits
A transformer used for isolation
Explanation - A shunt resistor creates a voltage drop used to calculate current.
Correct answer is: A low‑value resistor providing a measurable voltage drop proportional to current
Q.120 What is the primary function of a 'voltage transformer' in high‑voltage measurement?
To increase voltage to dangerous levels
To step down high voltage to a safe measurement range while isolating
To measure current directly
To provide mechanical support
Explanation - Voltage transformers reduce high voltage to levels safe for measurement instruments.
Correct answer is: To step down high voltage to a safe measurement range while isolating
Q.121 Which of the following is a typical safety feature of a high‑voltage test cabinet?
Open top design
Interlocked doors and grounded enclosure
No ventilation
No isolation from mains
Explanation - Interlocked doors prevent accidental access during testing.
Correct answer is: Interlocked doors and grounded enclosure
Q.122 Which of the following is not a typical component used in a high‑voltage measurement system?
Isolation transformer
High‑voltage probe
Shunt resistor
Thermocouple
Explanation - Thermocouples measure temperature, not voltage or current directly.
Correct answer is: Thermocouple
Q.123 Which of the following is a key requirement for resistors in high‑voltage dividers?
High temperature coefficient
Low ESR only
High power rating and voltage rating
Large physical size only
Explanation - Resistors must tolerate the high voltage and dissipate the heat generated.
Correct answer is: High power rating and voltage rating
Q.124 What is the main benefit of using a 'floating' measurement system in a high‑voltage environment?
Eliminates the need for grounding
Reduces measurement bandwidth
Provides galvanic isolation and lowers shock risk
Increases the voltage rating
Explanation - Floating systems isolate the measurement from ground, enhancing safety.
Correct answer is: Provides galvanic isolation and lowers shock risk
Q.125 Which of the following is a typical characteristic of a 'high‑voltage isolation transformer'?
No isolation
Low insulation resistance
High isolation resistance
Low voltage rating
Explanation - Isolation transformers are designed with high isolation resistance to protect equipment.
Correct answer is: High isolation resistance
Q.126 Which of the following is NOT a common method for measuring partial discharge?
PD detector
High‑bandwidth oscilloscope with a PD probe
Standard DMM
High‑frequency impedance measurement
Explanation - Standard DMMs cannot resolve the fast pulses associated with partial discharge.
Correct answer is: Standard DMM
Q.127 What is the most common method to measure high‑frequency current pulses in power electronics?
Using a shunt resistor only
Using a Rogowski coil or high‑frequency current probe
Using a standard ammeter
Using a mechanical lever
Explanation - These devices are designed for rapid current measurement.
Correct answer is: Using a Rogowski coil or high‑frequency current probe
Q.128 Which safety class is appropriate for equipment that may experience high‑voltage arcing up to 500 kV?
Class I
Class II
Class III
Class IV
Explanation - Class IV insulation can handle up to 500 kV and is used in HV applications.
Correct answer is: Class IV
Q.129 Which of the following is a typical use for a 'high‑voltage surge suppressor'?
Stepping down voltage only
Clamping voltage spikes to a safe level
Measuring current directly
Increasing the bandwidth
Explanation - Surge suppressors protect equipment by limiting transients.
Correct answer is: Clamping voltage spikes to a safe level
Q.130 In high‑voltage testing, which of the following is NOT a typical measurement device?
High‑voltage probe
Current transformer
Thermocouple
Voltage transformer
Explanation - Thermocouples measure temperature, not voltage or current directly.
Correct answer is: Thermocouple
Q.131 Which component provides a controlled path for a surge in a high‑voltage system?
Capacitor
Resistor
Surge arrestor
Inductor
Explanation - Surge arrestors clamp over‑voltage spikes to protect downstream components.
Correct answer is: Surge arrestor
Q.132 Which of the following is a typical safety requirement for a high‑voltage lab?
No protective gear
Strict isolation and clear signage
Work in open air
No ventilation needed
Explanation - Safety in HV labs demands isolation, signage, and protective gear.
Correct answer is: Strict isolation and clear signage
Q.133 In a high‑voltage measurement system, what is a key benefit of a 'voltage probe’s' guard ring?
Increases input capacitance
Provides a low‑impedance path for leakage
Reduces stray capacitance and improves isolation
Measures current
Explanation - Guard rings help maintain isolation and reduce leakage paths.
Correct answer is: Reduces stray capacitance and improves isolation
Q.134 Which of the following is a typical application for a current transformer?
Measuring DC current only
Measuring AC current in power systems
Measuring voltage across a resistor
Measuring temperature
Explanation - CTs provide an isolated, scaled representation of AC current for monitoring.
Correct answer is: Measuring AC current in power systems
Q.135 Which component is used to measure high‑frequency current pulses in power electronics?
High‑frequency current probe
Thermocouple
Resistor
Capacitor
Explanation - High‑frequency probes are designed for rapid current measurement.
Correct answer is: High‑frequency current probe
Q.136 What is the primary advantage of a high‑voltage probe with a built‑in isolation transformer?
It increases bandwidth
It isolates the probe from the high‑voltage source, improving safety
It reduces the input impedance
It allows direct measurement of DC voltage
Explanation - Isolation transformers prevent high‑voltage transients from reaching the measurement device.
Correct answer is: It isolates the probe from the high‑voltage source, improving safety
Q.137 Which of the following is a typical characteristic of a high‑voltage surge generator?
Produces continuous sinusoidal waveforms
Simulates lightning‑induced surges with short pulses
Measures DC voltage only
Used for mechanical testing only
Explanation - Surge generators deliver high‑voltage, short‑duration transients for testing.
Correct answer is: Simulates lightning‑induced surges with short pulses
Q.138 Which of the following best describes the use of a 'high‑frequency current probe' in power electronics?
Measuring DC current in a battery
Monitoring fast transient currents
Stepping down voltage for measurement
Measuring temperature
Explanation - High‑frequency probes capture rapid current changes for analysis.
Correct answer is: Monitoring fast transient currents
Q.139 Which of the following is a common safety precaution when working with high‑voltage equipment?
Use metal gloves for better contact
Work in a dry environment
Ignore cable ratings
Keep the work area open
Explanation - Dry conditions reduce the risk of arcing.
Correct answer is: Work in a dry environment
Q.140 What is a primary function of a 'voltage probe's' input capacitance?
To store charge for measurement
To limit the probe's bandwidth
To provide isolation
To increase the input impedance
Explanation - Input capacitance forms an RC filter limiting bandwidth.
Correct answer is: To limit the probe's bandwidth
Q.141 Which of the following is NOT a typical safety feature in a high‑voltage test cabinet?
Interlocked doors
Grounded enclosure
Open top for easy access
Ventilation system
Explanation - Open tops expose operators to hazards; cabinets are typically closed.
Correct answer is: Open top for easy access
Q.142 Which of the following is a key consideration when designing a high‑voltage resistor chain?
Power rating and voltage rating of each resistor
Color coding only
Resistance tolerance only
Physical size only
Explanation - Resistors must handle voltage across them and dissipate heat.
Correct answer is: Power rating and voltage rating of each resistor
Q.143 Which of the following is a common use for a high‑voltage probe in a lab?
Measuring high‑voltage waveforms safely
Measuring DC current only
Measuring temperature only
Measuring mechanical vibrations
Explanation - High‑voltage probes provide safe access to high‑voltage signals.
Correct answer is: Measuring high‑voltage waveforms safely
Q.144 What is the main advantage of using a 'high‑voltage shunt resistor' in a measurement circuit?
It provides isolation from the main circuit
It offers a simple, low‑cost method to measure high currents
It steps down voltage automatically
It acts as a voltage transformer
Explanation - A shunt resistor creates a known voltage drop proportional to current.
Correct answer is: It offers a simple, low‑cost method to measure high currents
Q.145 Which of the following is a typical safety requirement for a high‑voltage laboratory?
Open, unshielded work area
Strict isolation and clear signage
No need for personal protective equipment
Work in wet conditions
Explanation - Safety in HV labs demands isolation, signage, and protective gear.
Correct answer is: Strict isolation and clear signage
Q.146 Which of the following is NOT a typical application for a high‑frequency current probe?
Monitoring transient currents in power electronics
Measuring DC current in a battery
Diagnosing EMI sources
Measuring fast current spikes in motor drives
Explanation - High‑frequency probes are designed for AC and transient measurements.
Correct answer is: Measuring DC current in a battery