High-voltage engineering is branch of Electrical Engineering that deals with power systems at high voltages. It involves study of different types of stresses on equipment used in high-voltage transmission systems. Electrical Engineering XYZ presents High Voltage Engineering MCQs that are important for concept development university exams and other competitive exams. Test your electrical knowledge on HVAC and HVDC power systems. The concepts provided here are equally useful for engineering jobs and interviews especially for Power Engineers, technicians who are applying for the job in power industries.
Contents
- 1 The ideal lightning arrester is the one which
- 2 During impulse withstand test the impulse applied to the insulator is
- 3 The IR test of capacitor is performed by using ____________
- 4 The test which is performed on circuit breakers
- 5 The necessary condition for performing sphere gap test is
- 6 The electrostatic voltmeter using SF6 can measure the voltage level up to
- 7 The generating voltmeter is driven by ______________ which _____________ energy from measuring source
- 8 The breakdown of solid materials is mathematically related by the equation
- 9 Void discharges are classified as
- 10 Correct statement about Matched lines
The ideal lightning arrester is the one which
The ideal lightning arrester is the one which:
- Stops the flow of electric current above rated voltage
- Conducts electric current above rated voltage
- Any of these
- 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:
- 1/50 μ sec
- 0.1/0.05 μ sec
- 0.01/50 μ sec
- 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
- A Schering bridge
- The Chubb-Fortescue method
- The standard Ohmmeter
- 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:
- Short time current test
- Making capacity test
- Breaking capacity test
- 2 & 3
- 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:
- The length of gap should be 4 times greater than radius of sphere
- An impulse wave of 50000 kV should be applied
- Wave front time should be between 0.7 μs and 0.8 μs
- 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 ________:
- 500 kV
- 1000 kV
- 10000 kV
- 100000 kV
Correct answer: 2. 1000 kV
The generating voltmeter is driven by ______________ which _____________ energy from measuring source
The generating voltmeter is driven by ______________ which _____________ energy from measuring source:
- Constant speed motor, absorbs
- Constant speed motor, doesn’t absorb
- Variable speed motor, absorbs
- 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:
- Vb ln tb = constant
- Vb * tb = constant
- 3.87 Vb ln tb = constant
- 9.8 Vb * tb = constant
Correct answer: 1. Vb ln tb = constant
Void discharges are classified as
Void discharges are classified as:
- External partial discharges
- Internal partial discharges
- Any of these
- None of these
Correct answer: 2. Internal partial discharges
Correct statement about Matched lines
Correct statement about Matched lines:
- They have reflection
- They have no reflection
- They have reflection whose impedance equals the impedance of alternating power it
- None of the above
Correct answer: 2. They have no reflection
Continue reading:
- High Voltage Engineering MCQs Part 1
- High Voltage Engineering MCQs Part 2
- High Voltage Engineering MCQs Part 3
- High Voltage Engineering MCQs Part 4
- High Voltage Engineering MCQs Part 5
- High Voltage Engineering MCQs Part 6
- High Voltage Engineering MCQs Part 7
- High Voltage Engineering MCQs Part 8
- High Voltage Engineering MCQs Part 9
- High Voltage Engineering MCQs Part 10
- High Voltage Engineering MCQs Part 11