High Voltage Engineering MCQs

High Voltage Engineering MCQs by Electrical Engineering XYZ offers a comprehensive review of high voltage principles in a multiple-choice format. This resource delves into critical topics such as insulation coordination, breakdown mechanisms, HV equipment design, and safety protocols. With 100 thought-provoking questions, it challenges students and professionals alike to master concepts essential for power transmission, distribution, and industrial applications. Each question is meticulously crafted to test understanding and application, providing invaluable practice for exams and real-world scenarios. Whether you’re a student preparing for exams or a practitioner seeking to deepen your expertise, this MCQ guide equips you with the knowledge to excel in high voltage engineering.

The ideal lightning arrester is the one which

The ideal lightning arrester is the one which:

1. Stops the flow of electric current above rated voltage
2. Conducts electric current above rated voltage
3. Any of these
4. None of these

Correct answer: 2. Conducts electric current above rated voltage

During impulse withstand test the impulse applied to the insulator is

During impulse withstand test the impulse applied to the insulator is:

1. 1/50 μ sec
2. 0.1/0.05 μ sec
3. 0.01/50 μ sec
4. 0.001/50 μ sec

Correct answer: 1. 1/50 μ sec

Explanation: Impulse withstand test on insulators is one of the ten tests performed on insulators in high voltage laboratories.

The impulse withstand test, also known as the lightning impulse test, is a type of high-voltage test performed on insulators to evaluate their ability to withstand lightning strikes or other high-voltage transient surges. Insulators are used to support and isolate electrical conductors, such as power lines, from the structures they are attached to. These insulators must be able to withstand the sudden voltage surges caused by lightning strikes or other transient events.

During the impulse withstand test, a high-voltage impulse is applied to the insulator to simulate the effects of a lightning strike. The impulse voltage waveform used in the test has a steep front and a relatively long duration, similar to the waveform of a lightning strike. The magnitude of the impulse voltage is specified by international standards, such as IEC 60060 or ANSI/IEEE C62.41.

A standard impulse of 1/50 μ sec in provided to insulator. The wave having specified value under dry conditions with both positive and negative polarities is provided. If insulator sustains five consecutive applications of wave without any flash over or puncture it is considered to pass the test. If insulator fails two or more applications resulting in flashover it is considered to fail the test.

The test is typically conducted in a laboratory setting using specialized equipment. The insulator under test is subjected to a series of impulse voltages of increasing magnitude until it fails or reaches its specified impulse withstand capability. The failure criteria for insulators may include factors such as flashover (the formation of an electric arc across the surface of the insulator) or physical damage.

By performing impulse withstand tests on insulators, manufacturers and utilities can ensure that the insulators used in their electrical systems are capable of withstanding the high-voltage transients that may occur during lightning strikes or other transient events. This helps to ensure the safety and reliability of the electrical infrastructure.

The IR test of capacitor is performed by using

The IR test of capacitor is performed using

1. A Schering bridge
2. The Chubb-Fortescue method
3. The standard Ohmmeter
4. A Megger

Correct answer: 4. A Megger

Explanation: The correct answer to this Electrical Engineering XYZ multiple-choice question is “The IR test of a capacitor is performed using” is “A Megger.”

The IR test, also known as the insulation resistance test, is a common method used to assess the insulation condition of electrical equipment, including capacitors. This test measures the resistance between the insulation material and the conductive parts of the capacitor. Also check Electrical Engineering XYZ MCQ on Megger with statement A megger is generally here.

A Megger is a specialized instrument used for insulation resistance testing. It applies a high DC voltage to the capacitor and measures the leakage current flowing through the insulation. The instrument typically provides a digital display or analog meter to indicate the insulation resistance value.

Other than Megger the three options given here are incorrect. Since:

Option 1, the Schering bridge, is not used specifically for insulation resistance testing. It is a bridge circuit primarily used for accurately measuring the capacitance and dissipation factor of capacitors at power frequencies.

Option 2, the Chubb-Fortescue method, is not directly related to the insulation resistance test of capacitors. The Chubb-Fortescue method is a technique used for analyzing three-phase electrical systems to identify and quantify imbalances or asymmetries in the system.

Option 3, the standard Ohmmeter, is not suitable for performing the insulation resistance test on capacitors. Ohmmeters typically operate at lower voltages, which may not provide sufficient stress on the insulation to accurately measure its resistance.

Therefore, the most appropriate instrument for performing the insulation resistance test on a capacitor is a Megger.

The test which is performed on circuit breakers

The test which is performed on circuit breakers:

1. Short time current test
2. Making capacity test
3. Breaking capacity test
4. 2 & 3
5. All of these

Correct answer: 5. All of these

The necessary condition for performing sphere gap test is

The necessary condition for performing sphere gap test is:

1. The length of gap should be 4 times greater than radius of sphere
2. An impulse wave of 50000 kV should be applied
3. Wave front time should be between 0.7 μs and 0.8 μs
4. The length of gap should be smaller than radius of sphere

Correct answer: 4. The length of gap should be smaller than radius of sphere

Explanation: Sphere gap is one of the standard methods for the peak value DC, AC, and impulse voltages measurement.

Sphere gap test is employed for checking the voltmeters and other voltage measuring devices used in high voltage test circuits. In application of this method two identical metallic spheres separated by certain distance form a sphere gap. The sphere gap can be used for measurement of impulse voltage of either polarity provided that the impulse is of a standard wave form and has wave front time at least 1 micro sec. and wave tail time of 5 micro sec. During application of sphere gap test, the gap length between the sphere should not exceed a sphere radius.

The sphere gap test is a type of high-voltage test used to measure the voltage at which electrical breakdown occurs in air. It involves creating a gap between two conducting spheres and applying a high voltage across the gap until a spark or breakdown occurs.

The length of the gap in the sphere gap test is an important parameter. The gap should be smaller than the radius of the sphere to ensure that the electric field is concentrated at the tip of the sphere. This configuration helps to achieve a more uniform and controlled breakdown of the air gap.

Option 1, stating that the length of the gap should be four times greater than the radius of the sphere, is incorrect. Such a large gap length would spread the electric field over a larger area, leading to a less controlled breakdown and potentially affecting the accuracy of the test.

Option 2, mentioning the application of an impulse wave of 50,000 kV, is incorrect. The sphere gap test typically uses a high-voltage DC source or a power frequency AC source. The specific voltage level may vary depending on the application, but it is not necessary to use an impulse wave of 50,000 kV.

Option 3, specifying a wave front time between 0.7 μs and 0.8 μs, is also incorrect. The wave front time is not a critical factor in the sphere gap test. The focus is primarily on the gap length and the voltage applied.

Therefore, the necessary condition for performing a sphere gap test is that the length of the gap should be smaller than the radius of the sphere.

The electrostatic voltmeter using SF6 can measure the voltage level up to

The electrostatic voltmeter using SF6 can measure the voltage level up to ________:

1. 500 kV
2. 1000 kV
3. 10000 kV
4. 100000 kV

Correct answer: 2. 1000 kV

The generating voltmeter is driven by

The generating voltmeter is driven by ______________ which _____________ energy from measuring source:

1. Constant speed motor, absorbs
2. Constant speed motor, doesn’t absorb
3. Variable speed motor, absorbs
4. Variable speed motor, doesn’t absorb

Correct answer: 2. Constant speed motor, doesn’t absorb

The breakdown of solid materials is mathematically related by the equation

The breakdown of solid materials is mathematically related by the equation:

1. V_b ln t_b = constant
2. V_b * t_b = constant
3. 3.87 V_b ln t_b = constant
4. 9.8 V_b * t_b = constant

Correct answer: 1. Vb ln tb = constant

Void discharges are classified as

Void discharges are classified as:

1. External partial discharges
2. Internal partial discharges
3. Any of these
4. None of these

Correct answer: 2. Internal partial discharges

Correct statement about Matched lines

Correct statement about Matched lines:

1. They have reflection
2. They have no reflection
3. They have reflection whose impedance equals the impedance of alternating power it
4. None of the above

Correct answer: 2. They have no reflection

Marx multistage impulse generator model involves

Marx multistage impulse generator model involves:

1. High ohmic resistances
2. Low ohmic resistances
3. Both of these
4. None of these

Correct answer: 3. Both of these

Four statements are mentioned about the rod gaps, mention the correct statement

Four statements are mentioned about the rod gaps, mention the correct statement:

1. Rod gaps are most accurate measurement devices
2. The use of rod gaps is not allowed as a.c measurement devices
3. Rod gaps contain 7 capped rods that are spaced at 1 mm
4. None of these is correct

Correct answer: 2. The use of rod gaps is not allowed as a.c measurement devices

Cascaded transformers are most commonly employed

Cascaded transformers are most commonly employed in high voltage testing labs. The major __________ associated with the cascading configuration is that _________ stages are loaded more as compared to _________ stages.

1. advantage, lower, upper
2. disadvantage, lower, upper
3. advantage, upper, lower
4. disadvantage, upper, lower

Correct answer: 2. disadvantage, lower, upper

According to stressed oil volume theory, the breakdown strength __________ the stressed oil volume

According to stressed oil volume theory, the breakdown strength __________ the stressed oil volume:

1. Is inversely proportional to
2. Is directly proportional to
3. Is independent of
4. None of these

Correct answer: 1. Is inversely proportional to

Recurrent surge generator provides

Recurrent surge generator provides:

1. Two current impulses
2. A large current impulse
3. A large magnitude impulse voltage
4. A smaller magnitude impulse voltage

Correct answer: 4.  A smaller magnitude impulse voltage

The dielectric strength of Mica is

The dielectric strength of Mica is:

1. 1000 kV/in
2. 1500 kV/in
3. 5000 kV/in
4. 10000 kV/in

Correct answer: 3. 5000 kV/in

The correct statement about SF6 gas

The correct statement about SF₆ gas:

1. Under normal circumstances, It can be used above 14 kg/cm²
2. Under normal circumstances, it can’t be used above 14 kg/cm²

Correct answer: 2. Under normal circumstances, it can’t be used above 14 kg/cm²

Usually, the Insulation of power systems is classified in categories

Usually, the Insulation of power systems is classified in categories:

1. Internal
2. Mid
3. External
4. All of these
5. 1 & 2
6. 1 & 3

Correct answer: 6. 1 & 3 (Internal & External)

External insulation comprises

External insulation comprises:

1. Air & Porcelain
2. Paper & Oil Insulation
3. Aluminium & Copper
4. Gold & Silver

Correct answer: 1. Air & Porcelain

The generating voltmeter is

The generating voltmeter is:

1. A Non-linear electromechanical device
2. A variable capacitor electrostatic device
3. Asynchronous generator with plc module

Correct answer: 2. A variable capacitor electrostatic device

The first step of transformer Impulse testing is to

The first step of transformer Impulse testing is to:

1. Apply an impulse whose magnitude equals 0.75 times the BIL
2. Apply a chopped impulse whose magnitude is 2 times the BIL
3. Apply a full wave impulse whose magnitude is 1.19 times the BIL
4. Apply a full impulse whose magnitude is 0.8 times the BIL

Correct answer: 1. Apply an impulse whose magnitude equals 0.75 times the BIL

Chubb and Fortescue method of measuring peak AC voltages used the circuit

Chubb and Fortescue method of measuring peak a.c voltages used the circuit:

1. An inductor, two diodes, and voltmeter
2. A capacitor, two diodes and an ammeter
3. A potential transformer, a surge arrester, and gold leaf electroscope
4. A current transformer, ammeter and oscilloscope

Correct answer: 2. A capacitor, two diodes and an ammeter

Usually, the impulse voltage is

Usually, the impulse voltage is:

1. Unidirectional
2. Bidirectional
3. Tridirectional
4. Quadridirectional

Correct answer: 1. Unidirectional

The high ohmic series resistance micrometer can utilize

The high ohmic series resistance micrometer can utilize __ for protection against resistance failure:

1. Paper gap
2. Zener diode
3. Both of these
4. None of these

Correct answer: 3. Both of these

Corona occurs in

Corona occurs in:

1. Conductors carrying Alternating currents
2. Conductors carrying Direct Currents
3. Both of these
4. None of these

Correct answer: 3. Both of these

The input voltage in Cockroft-Walton circuit

The input voltage in Cockroft-Walton circuit is 50 kV, the load current is 125 mA and the supply frequency is 50 Hz. Each capacitor 10 nF. The optimum number of stages required to achieve the maximum output voltage is:

1. 1 stage
2. 4 stages
3. 8 stages
4. 16 stages

Correct answer: 1. 1 Stage

The standard shape of impulse wave as specified by the American standard is 1.5/40 μsec. The number 1.5 is

The standard shape of impulse wave as specified by the American standard is 1.5/40 μsec. The number 1.5 is:

1. Wave front
2. Wave tail
3. Wave head
4. Wave footing

Correct answer: 1. Wave front

What is avoided in construction of impulse measuring voltage dividers

Generally _____________ are avoided in construction of impulse measuring voltage dividers because they ___________:

1. Capacitors, might posses stray capacitance
2. Inductors, can inducestray capacitance
3. Capacitors, carry capacitive impedance
4. Inductors, are very expensive

Correct answer: 2. Inductors, can inducestray capacitance

The scale of generating voltmeter

The generating voltmeter has a _______ scale:

1. Linear
2. Non-linear

Correct answer: 1. Linear

The device which uses Litchenberg sulphur dust image to record surges

The device which uses Litchenberg sulphur dust image to record surges:

1. Surge arrester
2. Klydonograph
3. Hall generator
4. None of these
   • Correct answer: 2. Klydonograph

1. The relative dielectric strength of SF6 as compared to air is:
   • 1.5 times
   • 2 times
   • 2.5 times
   • 3 times
     • Correct answer: 2.5 times
2. The correct statement about Paschen’s law states that breakdown voltage of a uniform gap is directly proportional to:
   1. Pressure of the gas
   2. Separation of electrode
   3. Material of electrode
   4. All of these
   5. 1 & 3
      • Correct answer: 4. All of these
3. For determining intrinsic strength of dielectric the applied voltage should be of the order of:
   1. 10^-8 sec
   2. 10^-16 sec
   3. 10^-24 sec
   4. 10^-32 sec
      • Correct answer: 1. 10^-8 sec
4. The ratio of voltage drop in a 6 stage to 3 stage Cockroft Walton circuit is:
   1. 6
   2. 2
   3. 9
   4. 1
5. Sometimes a void appears in the dielectric, the correct statement regarding the void is that its:
   1. Electric field strength is lower than that of the dielectric
   2. Electric field strength is higher than that of the dielectric
   3. Electric field strength is exactly similar to the dielectric
      • Correct answer: 2. Electric field strength is lower than that of the dielectric
6. The onset voltage for Trichel pulses:
   1. Increases exponentially with increase in gap length
   2. Increases exponentially with decrease in gap length
   3. Increases directly with increase in gap length
   4. Is independent of gap length
      • Correct answer: 4. Is independent of gap length
7. The frequency response of Rogowski coil is flat upto:
   1. 100 MHz
   2. 200 MHz
   3. 500 MHz
   4. 1000 MHz
      • Current answer: 1. 100 MHz
8. The small load current in Cockroft – Walton circuit means:
   1. Voltage drop is very large
   2. Voltage drop is small
   3. None of these
   4. Can’t predict
      • Current answer: 2. Voltage drop is small
9. The dielectric strength of liquids is of the order:
   1. 100 kV/cm
   2. 1000 kV/cm
   3. 5000 kV/cm
   4. 10000 kV/cm
      • Current answer: 1. 100 kV/cm
10. Temperature limit for Class H insulation is:
    1. 90°C
    2. 180°C
    3. 200°C
    4. 400°C
       • Correct answer: 2. 180°C

1. The worst gap for measuring the voltages is:
   1. Field gap
   2. Sphere gap
   3. Rod gap
   4. All of these
      • Correct answer: 3. Rod gap
2. Usually Mole’s bridge is used to measure __________ frequency measurements:
   1. Low
   2. High
   3. Both of these
   4. None of these
      • Correct answer: 1. Low
3. Impulse tests are performed on transformers:
   1. To determine insulation ability against transient voltages
   2. To test the moisture content in fuel
   3. Both of these
   4. All of these
      • Correct answer: 1. To determine insulation ability against transient voltages
4. The penning effect demonstrates:
   1. Decrease in dielectric strength of mixture of gases
   2. Increases in dielectric strength of mixture of gases
   3. Decrease in dielectric strength of a gas
   4. Increase in dielectric strength of a gas
      • Correct answer: 1. Decrease in dielectric strength of mixture of gases
5. Usually, the switching surge is ___________by the operation of switches or breakers:
   1. Self-induced
   2. Not-induced
6. According to suspended particle theory, if ε₁ > ε₂, then force F is directed towards:
   1. Minimum stress areas
   2. Maximum stress areas
   3. Both of these
   4. None of these
      • Correct answer: 1. Minimum stress areas
7. The phenomenon of corona takes place in case of:
   1. Alternating currents
   2. Direct Currents
   3. Both of these
   4. None of these
      • Correct answer: 3. Both of these
8. The phenomenon of treeing is expected to occur in the dielectric which has a non-uniform field. The correct statement about treeing:
   1. It occurs at once in single discharge
   2. The lower the voltages, the higher is the chance of treeing
   3. It occurs in two discharges
   4. None of these
      • Correct answer: None of these
9. According to bubble theory of liquid breakdown, the vapor bubble elongates __________ direction of the electric field and its volume ___________ during elongation:
   1. in the, increases gradually
   2. away from the, remains constant
   3. in the, remains constant
   4. away from the, increases gradually
      • Correct answer: 3. in the, remains constant
10. The gas which is employed as insulating material:
    1. Oxygen
    2. Sulphur Hexafluoride
    3. Tetrafluoromethane
    4. Ethylamine
       • Correct answer: 2. Sulphur Hexafluoride

1. Large power transformers are best protected by:
   1. Station type lightning arrestors
   2. Distribution type lightning arrestors
   3. Line type lightning arrestors
   4. None of these
      • Correct answer: 1. Station type lightning arrestors
2. A capacitance-resistance circuit is used to measure the ripple voltages in d.c system. During this process the important condition which should be met is:
   1. ω CR >> 1
   2. ω CR << 1
   3. ω CR = 1
   4. ω CR = 0
      • Correct answer: 1. ω CR >> 1
3. Circuit breaker dielectric tests include:
   1. 1-minute dry withstand test
   2. 1-minute wet withstand test
   3. Impulse voltage dry withstand test
   4. All of these
   5. None of these
      • Correct answer: 4. All of these
4. The intrinsic breakdown in solids is of the order of __________ sec:
   1. 10^-4 s
   2. 10^-8 s
   3. 10^-16 s
   4. 10^-20 s
5. Large size sphere gaps are installed in:
   1. Horizontal configuration
   2. Vertical configuration
   3. Any of these
   4. None of these
      • Correct answer: 2. Vertical configuration
6. Recurrent surge generator provides the impulse voltage which has __________ magnitude and to whom the equipment should respond in a ___________ mode:
   1. Smaller, Nonlinear
   2. Smaller, Linear
   3. Larger, Nonlinear
   4. Smaller, Nonlinear
      • Correct answer: 2. Smaller, Linear
7. The criterion for determining the number of stages for maximum output voltage in Cockroft – Walton is:
   1. Frequency of input
   2. Capacitance of each stage
   3.  Required kVA
   4. None of these
      • Correct answer: 4. None of these
8. ______________ is a type of surge diverter:
   1. Rod gap
   2. Valve type of lightning arrester
   3. Protector tube
   4. All above
      • Correct answer: 4. All above
9. During their manufacturing process, the High voltage power cables are subject to bending test. The statement which correctly explains this test is:
   1. The cable is bent and piston is allowed to fall on it at a comparatively lower power
   2. Firstly voltage test is performed then entire cable is bent in zig-zag position and voltage regulation is checked during process
   3. Cable is bent around cylinder to make one turn is unwound, rewound thrice following a voltage test in start and end
   4. None of these
      1. Correct answer: 3. Cable is bent around cylinder to make one turn is unwound, rewound thrice following a voltage test in start and end

1. The dielectric strength of air is approx:
   1. 10 kV/in
   2. 20 kV/in
   3. 200 kV/in
   4. 5000 kV/in
      • Correct answer: b. 20 kV/in
2. ____________ is/are expected to have treeing phenomenon:
   1. Capacitors
   2. Cables
   3. Dielectrics
   4. All of these
      • Correct answer: 4. All of these
3. Chubb–Fortescue method of measurement of a.c peak voltage values contains:
   1. A capacitor, two diodes, an ammeter, a Resistor and an overvoltage protector
   2. An inductor, two diodes, an ammeter, a Resistor and an overvoltage protector
   3. A capacitor, one diode, a voltmeter, a Resistor and an overvoltage protector
   4. An inductor, two diodes, a voltmeter, a Resistor and an overvoltage protector
      • Correct answer: A capacitor, two diodes, an ammeter, a Resistor and an overvoltage protector
4. Capacitor bushing use _______________ type of paper:
   1. Oil impregnated paper
   2. Resin bonded paper
   3. Resin impregnated paper
   4. All of these
      • Correct answer: 4. All of these
5. The radial stress of resin bonded paper capacitor busing is:
   1. 10 kV/cm
   2. 20 kV/cm
   3. 30 kV/cm
   4. 40 kV/cm
      • Correct answer: 2. 20 kV/cm
6. The long-term breakdown is also known as:
   1. Ageing breakdown
   2. Menacing breakdown
   3. Both of these
   4. None of these
      • Correct answer: 1. Ageing breakdown
7. __________________ considers the dependence of breakdown strength of liquid on length of gap:
   1. Suspended particle theory
   2. Bubble theory
   3. Stressed oil volume theory
   4. None of these
      • Correct answer: 4. None of these
8. Experiments suggest that breakdown strength of liquids depends primarily on:
   1. Length of gap
   2. Hydrostatic pressure
   3. Impurity particles
      • Correct answer: 1. Length of gap
9. Paschen law relates the breakdown voltage with pressure and electrode separation. For a particular gas the correct relationship as per Paschen’s law is:
   1. Breakdown voltage is directly proportional to pressure and inversely to separation
   2. Breakdown voltage is directly proportional to separation and inversely to pressure
   3. Breakdown voltage is inversely proportional to both
   4. Breakdown voltage is directly proportional to both
      • Correct answer: 4. Breakdown voltage is directly proportional to both
10. The cable routine test involves the application of ac voltage which is ________ times rated rated voltage and for approximately _______ minutes:
    1. 1/2, 2 minutes
    2. 1.5, 3 minutes
    3. 2.5, 10 minute
    4. 10, 50 minute
       • Correct answer: 2.5, 10 minute

1. The most recommended gap under usual conditions for measuring the voltages is:
   1. Field gap
   2. Sphere gap
   3. Rod gap
   4. All of these
      • Correct answer: 2. Sphere gap
2. According to Paschen’s law, the breakdown voltage = __________:
   1. F (p/d)
   2. F / (pd)
   3. F (pd)
   4. F + p + d
      • Correct answer: 3. F (pd)
3. The voltage at which electrical stress in the insulation makes the insulator to fail is:
   1. Withstand voltage
   2. Impulse voltage
   3. Disruptive discharge voltage
   4. None of these
      • Correct answer: 3. Disruptive discharge voltage
4. Sphere gaps can measure:
   1. Peak value of d.c
   2. Peak value of a.c
   3. Both of these
   4. None of these
      • Correct answer: 3. Both of these
5. The design of Marx multistage impulse generator involves the condensers which are:
   1. Charged in parallel and discharged in series
   2. Charged in series and discharged in series
   3. Charged in parallel and discharged in parallel
   4. Charged in series and discharged in parallel
      • Correct answer: 1. Charged in parallel and discharged in series
6. The radial stress of Oil impregnated paper capacitor busing is:
   1. 10 kV/cm
   2. 20 kV/cm
   3. 30 kV/cm
   4. 40 kV/cm
      • Correct answer: 4. 40 kV/cm
7. Reason: The measured breakdown voltage is more influenced by weak medium than the solid medium. Affirmation: The treeing phenomenon occurs in dielectrics which have a non-uniform field.
   1. Affirmation is caused by the reason
   2. Affirmation and reason have no relationship
   3. Reason is correct, affirmation is wrong
   4. Affirmation is correct, reason is wrong
   5. None of these
      • Correct answer: Affirmation is caused by the reason
8. According to suspended particle theory, if ε₂ > ε₁, then force F is directed towards:
   1. Minimum stress areas
   2. Maximum stress areas
   3. Both of these
   4. None of these
      • Correct answer: 2. Maximum stress areas
9. Which statement correctly illustrates the Suspended particle theory:
   1. The larger the size of impurity particles, the lower the breakdown strength
   2. The larger the size of impurity particles, the higher the breakdown strength
      • Correct answer: 1. The larger the size of impurity particles, the lower the breakdown strength
10. Liquid A is a pure liquid. Liquid
    1. Liquid A > Liquid B
    2. Liquid A = Liquid B
    3. Liquid A < Liquid B
       • Correct answer: 1. Liquid A > Liquid B

High voltage engineering for the insulation applications most likely requires

1. High voltage engineering for the insulation applications most likely requires:
   1. Non-flammable gases with high dielectric strength
   2. Non-flammable gases with lower dielectric strength
   3. Flammable gases with high dielectric strength
   4. Flammable gases with lower dielectric strength
      • Correct answer: 1. Non-flammable gases with high dielectric strength

The high voltage d.c test on cable involves the application of direct current which is _________ times the rated dc voltage for approximately ________ minutes

1. The high voltage d.c test on cable involves the application of direct current which is _________ times the rated dc voltage for approximately ________ minutes:
   1. 0.8 times, 15
   2. 1.8 times, 30 minutes
   3. 2.96 times, 45 minutes
   4. 3.22 times, 57
      • Correct answer: 2. 1.8 times, 30 minutes

High ohmic series resistance micrometer is recommended for measuring

1. High ohmic series resistance micrometer is recommended for measuring:
   1. D.C High voltages
   2. D.C High current
   3. A.C High voltages
   4. A.C High currents
      • Correct answer: 1. D.C High voltages

Impulse ratio of a material depends on

1. Impulse ratio of a material depends on:
   1. Shape of wave
   2. Polarity of impulse wave
   3. Both of these
   4. None of these
      • Correct answer: 3. Both of these

The high voltage test which is performed on transformers

1. The high voltage test which is performed on transformers:
   1. Impulse test
   2. Induced overvoltage test
   3. Partial discharge test
   4. All of these
   5. None of these
      • Correct answer: 4. All of these

Temperature limit for Class Y insulation is

1. Temperature limit for Class Y insulation is:
   1. 90°C
   2. 180°C
   3. 200°C
   4. 400°C
      • Correct answer: 1. 90°C

_________________ carry the process of ionization

1. _________________ carry the process of ionization:
   1. Negative Ions
   2. Positive Ions
   3. Both of these
   4. None of these
      • Correct answer: 3. Both of these

The ripple voltage of half wave rectifier is

1. The ripple voltage of half wave rectifier is:
   1. Smaller than full wave rectifier
   2. Larger than full wave rectifier
   3. Equal to full wave rectifier
   4. Half then full wave rectifier
      • Correct answer: 2. Larger than full wave rectifier

Squirrel cage shunts are _________ and they dissipate __________ as compared to

1. Squirrel cage shunts are _________ and they dissipate __________ as compared to
   coaxial shunts:
   1. High ohmic shunts, smaller energy
   2. High ohmic shunts, larger energy
   3. Low ohmic shunts, smaller energy
   4. Low ohmic shunts, larger energy
      • Correct answer: 2. High ohmic shunts, larger energy

During the dielectric power factor test on the cable, it is noticed that the source is not able to supply the required charging current, the optimal solution is to connect

1. During the dielectric power factor test on the cable, it is noticed that the source is not able to supply the required charging current, the optimal solution is to connect:
   1. Series capacitor
   2. Series inductor
   3. Shunt capacitor
   4. Any of these
      • Correct answer: 2. Series inductor

1. The term counterpoise in high voltage engineering is referred to:
   1. A large-sized sphere gap
   2. Galvanized wire which runs in parallel to the overhead line
   3. A surge arrester which is installed at distribution station
   4. None of these
      • Correct answer: 2. Galvanized wire which runs in parallel to the overhead line
2. The standard shape of impulse wave as specified by the American standard is 1.5/40 μsec. The number 40 is:
   1. Wave front
   2. Wave tail
   3. Wave head
   4. Wave footing
      • Correct answer: 2. Wave tail
3. Under standard atmospheric conditions the breakdown voltage for an air gap of 5 mm in a uniform field is:
   1. 22.52 kV
   2. 16.40 kV
   3. 765 kV
   4. 987 kV
      • Correct answer: 2. 16.40 kV
4. ____________ is the input to impulse generator:
   1. DC Supply
   2. AC Supply
   3. Impulse
   4. Triangular a.c
      • Correct answer: 1. DC Supply
5. The term wave front is associated with ____________:
   1. Sin
   2. Triangular
   3. Square
   4. Impulse
      • Correct answer: 4. Impulse wave
6. The term wave front time represents the time taken to:
   1. Reach from zero to its maximum peak value
   2. Reach from 0.7 of peak to peak and again back to 0.7 after
   3. Reach from 0.8 of peak to 0.9 of peak
   4. None of these
      • Correct answer: 1. Reach from zero to its maximum peak value
7. An overhead line has a surge impedance of 100 ohms. It is terminated by a resistor R. Value of R which should be used to avoid reflection is:
   1. 10 ohms
   2. 100 ohms
   3. 400 ohms
   4. 1036 ohms
      • Correct answer: 2. 100 ohms
8. ____________ is widely employed for measuring HV voltages:
   1. Field gap
   2. Sphere gap
   3. Rod gap
   4. All of these
      • Correct answer: 2. Sphere gap
9. The dielectric strength of Glass is:
   1. 1000 kV/in
   2. 1500 kV/in
   3. 2000-3000 kV/in
   4. 5000-10000 kV/in
   5. 20000 kV/in
      1. Correct answer: 3. 2000-3000 kV/in
10. Temperature limit for Class
    1. 90°C
    2. 120°C
    3. 180°C
    4. 400°C
       • Correct answer: 2. 120°C

While installing sphere gaps, smaller sphere gaps are installed in

1. While installing sphere gaps, smaller sphere gaps are installed in:
   1. Horizontal configuration
   2. Vertical configuration
   3. Any of these
   4. None of these
      • Correct answer: 1. Horizontal configuration

The impulse test of the transformer is done by using

1. The impulse test of the transformer is done by using:
   1. Full wave standard impulse
   2. Half wave standard impulse
   3. Both of these
   4. None of these
      • Correct answer: Full wave standard impulse

The radial stress of resin impregnated paper capacitor busing is

1. The radial stress of resin impregnated paper capacitor busing is:
   1. 10 kV/cm
   2. 20 kV/cm
   3. 30 kV/cm
   4. 40 kV/cm
      • Correct answer: 3. 30 kV/cm

The correct statement about the Chubb–Fortescue method

1. The correct statement about the Chubb–Fortescue method:
   1. It is used for the measurement of a.c peak voltage
   2. It is used for the measurement of d.c peak voltage
   3. Both of these
   4. None of these
      • Correct answer: 1. It is used for the measurement of a.c peak voltage

The transient phenomenon is ____________ function of time which lasts for _________ duration

1. The transient phenomenon is ____________ function of time which lasts for _________ duration:
   1. Aperiodic, short
   2. Aperiodic, long
   3. Periodic, short
   4. Periodic, long
      • Correct answer: 1. Aperiodic, short

Internal insulation comprises

1. Internal insulation comprises:
   1. Air & Porcelain
   2. Paper & Oil Insulation
   3. Aluminium & Copper
   4. Gold & Silver
      • Correct answer: 2. Paper & Oil Insulation

The switching surge can be best explained as

1. The switching surge can be best explained as:
   1. D.C in nature
   2. A.C in nature
   3. Very long duration transient voltage
   4. Short duration transient voltage
      • Correct answer: 4. Short duration transient voltage

_______________ method is extensively employed for protection against __________ overvoltages

1. _______________ method is extensively employed for protection against __________ overvoltages:
   1. Shielding, External
   2. Shielding, Internal
   3. Non-shielding, all types of
   4. None of these
      • Correct answer:  1. Shielding, External

The rectifier which generates high voltage d.c from a.c

1. The rectifier which generates high voltage d.c from a.c:
   1. Half-wave rectifiers
   2. Full wave rectifiers
   3. Voltage doubler type rectifiers
   4. All of these
      • Correct answer: 4. All of these

Hall effect generators are used to measure

1. Hall effect generators are used to measure:
   1. Direct current
   2. High-frequency alternating current
   3. Both of these
   4. None of these
      • Correct answer: 3. Both of these

Detector circuit used for measuring radio interference voltages

The detector circuit used for measuring radio interference voltages is equipped with a measuring device that is used to measure which of the following values:

1. Quasi-peak value
2. Average value
3. Peak value
4. All of above

Correct answer: 4. All of above

Explanation: The measuring device in the detector circuit for radio interference voltages is designed to measure multiple characteristics of the signal. It can measure the average value, which is the mean value of the voltage waveform over a specific time period. It can also measure the peak value, which represents the highest value reached by the voltage waveform. Additionally, it can measure the quasi-peak value, which is a modified measurement that takes into account the effect of amplitude modulation on interference signals. Therefore, the measuring device is capable of measuring all of these values: average, peak, and quasi-peak.

Also see: Complete List of Electrical Engineering MCQs here

In large impulse generators, the spark gaps are usually

In large impulse generators, the spark gaps are usually

1. Sphere gaps
2. Hemispherical gaps
3. Either of these
4. None of these

Correct answer: 3. Either of these

Explanation: In large impulse generators, the spark gaps serve as a means to generate high-voltage impulses. These spark gaps can take the form of either sphere gaps or hemispherical gaps. Both types of gaps have proven to be effective in generating the necessary high-voltage discharges. The choice between sphere gaps and hemispherical gaps may depend on various factors such as the specific design requirements of the generator or the preferences of the manufacturer. Therefore, in large impulse generators, the spark gaps can be either sphere gaps or hemispherical gaps, providing flexibility in their design and implementation.

Which of below mentioned is an example of artificial fibre is

Which of below mentioned is an example of artificial fibre is

1. Cotton
2. Flax
3. Rayon
4. Silk

Correct answer: 3. Rayon

Explanation: Artificial fibers are man-made fibers that are created using chemical processes. Rayon is a specific example of an artificial fiber. It is derived from natural cellulose, typically obtained from wood pulp or other plant sources. Rayon is valued for its softness, breathability, and versatility, making it widely used in the textile industry. It is commonly used in the production of clothing, upholstery, and various other textile products. Also see: Meaning of Core number in Electrical cables here

On the other hand, options 1, 2, and 4: cotton, flax, and silk – are examples of natural fibers. Cotton is obtained from the cotton plant, flax is derived from the flax plant, and silk is produced by silkworms. These natural fibers are not considered artificial fibers as they are sourced directly from nature without extensive chemical processing.

In case of high voltage conductors at high pressures, if voltage is positive, the corona appears as

In case of high voltage conductors at high pressures, if voltage is positive, the corona appears as

1. Reddish glowing spots
2. Uniform bluish white sheath
3. Uniform greenish spots
4. Any of above

Correct answer: 2. Uniform bluish white sheath

Explanation: When high voltage is applied to conductors at high pressures, the phenomenon of corona discharge can occur provided that Critical Disruptive Voltage for Corona Formation is exceeded. Corona discharge is characterized by the ionization of the surrounding air due to the high electric field strength. If the voltage on the conductor is positive, the corona appears as a uniform bluish white sheath surrounding the conductor. This bluish white sheath is the result of the ionization of air molecules, which emit light in the visible spectrum. It is important to note that the appearance of corona can vary depending on factors such as voltage level, conductor shape, and environmental conditions.

Also see: 5 Different types of conductors used in transmission lines

In order to accurately measure ripple voltage in dc systems using CR circuit, the condition to be satisfied is

In order to accurately measure ripple voltage in dc systems using CR circuit, the condition to be satisfied is:

1. ωCR >> 1
2. ωCR << 1
3. ωCR = 1
4. None of above

Correct answer: 1. ωCR >> 1

Explanation: In High Voltage Engineering, one of the simple method of measuring the ripple voltage is by using a capacitance-resistance circuit