# High Voltage Technology Questions Past Papers

## High Voltage Technology Questions  Past Papers 1

Time Allowed: 3 hours

Total Marks:    70, Passing Marks (35)

Q.1 State and explain Paschen’s law with the help of curve. How do you account for the minimum
voltage for breakdown under a given condition?

Q.2 Explain briefly various theories of breakdown in solid dielectrics.

Q.3 Explain different types of energy process involved in breakdown of insulators with the help of chemical
reactions.

Q.4 Design the impulse high voltage generator. Draw the circuit diagram of high voltage impulse generator

Q.5 Describe the arrangement of insulators for performing various tests. List out various tests to be carried
out on insulator and give a brief account of each test.

Q.6 List the causes of over voltage? What is lightening stroke to the ground. Explain the mechanism of
lightening stroke.

Q.7 A steady current of 600 µA flows through the plane electrode separated by a distance of 0.5 cm when a
voltage of 10 kV is applied. Determine the Townsend’s first ionization coefficient if a current of 60 µA
flows when the distance of separation is reduced to 0.1 cm and the field is kept constant at the previous
value. Determine the value for second ionization coefficients if the minimum current observed is 6 ×
10–14A

Q.8 Explain the manifestation of corona losses in transmission line system? Compare power loss due to
corona in height and sea level.

## High Voltage Technology Questions  Past Papers 2

Time Allowed: 3 hours

Total Marks:    70, Passing Marks (35)

Q.1 Discuss various factors which affect breakdown of gases. Define Townsend’s first and second ionization coefficients. Explain the Townsends criterion for a spark.

Q.2 Explain briefly various theories of breakdown in solid dielectrics.

Q.3 a) Why we use high voltage (HV) and introduced HV problems
b) Explain the photo excitation and collision ionization process for breakdown in dielectric material

Q.4 Explain Cockroft-Walton voltage multiplier circuit for high voltage DC generation with the help of neat sketches

Q.5 What are the sources of liquid dielectric contamination? State various processes which lead to formation of bubbles in liquid dielectrics and explain clearly cavity breakdown mechanism in liquid dielectrics.

Q.6 Explain the procedure of high voltage test on transformer bushings and cable

Q.7 A 3-phase, 220 kV, 50 Hz transmission line consists of 1•5 cm radius conductor arranged in equilateral triangular fashion with line spacing of 6cm. If the temperature is 40ºC and atmospheric pressure is 76 cm, calculate the corona loss per km of the line. Take mo= 0•85

Q.8 Write a notes on any two of the following
a) Problems caused by corona discharge in transmission lines
b) Over voltage due to switching surges
c) Streamer breakdown

## High Voltage Technology Questions  Past Papers 3

Time Allowed: 3 hours

Total Marks:    70, Passing Marks (35)

Q1. a) Discuss Townsend curve for the breakdown of gaseous dielectrics
b) Prove that: I = I0e-αd .

Q2. Discuss various methods used for the testing of high voltage cables

Q3. What are different ways/methods for the generation of HVAC? Discuss any one in detail.

Q4. What is the breakdown of insulator. Explain the breakdown phenomena of insulator in detail. Discuss different ionization processes briefly.

Q5. Explain any two methods of high voltage measurement with the help of figure diagrams.

Q6. A 3-phase, 220 kV, 50 Hz transmission line consists of 1•5 cm radius conductor spaced 2 meters apart in equilateral triangular formation. If the temperature is 40ºC and atmospheric pressure is 76 cm, calculate the corona loss per km of the line. Take mo= 0•85

Q7. What are the characteristics of corona discharge? Explain manifestation of Corona discharge? What are the advantages and disadvantages of corona discharge?

Q8. Write a note on any TWO of the following:
a) Insulation coordination
b) Pollution effect on insulator
c) Voltage drop around insulation.

## High Voltage Technology Questions  Past Papers 4

Time Allowed: 3 hours

Total Marks:    70, Passing Marks (35)

Q.1 State and explain Paschen’s law with the help of curve. How do you account for the minimum voltage for breakdown under a given pdcondition?

Q.2 Explain briefly various theories of breakdown in solid dielectrics.

Q.3 Explain different types of energy process involved in breakdown of insulators with the help of chemical reactions.

Q.4 Design the impulse high voltage generator. Draw the circuit diagram of high voltage impulse generator

Q.5 Describe the arrangement of insulators for performing various tests. List out various tests to be carried out on insulator and give a brief account of each test.

Q.6 List the causes of over voltage? What is lightening stroke to the ground. Explain the mechanism of lightening stroke.

Q.7 A steady current of 600 µA flows through the plane electrode separated by a distance of 0.5 cm when a voltage of 10 kV is applied. Determine the Townsend’s first ionization coefficient if a current of 60 µA flows when the distance of separation is reduced to 0.1 cm and the field is kept constant at the previous value. Determine the value for second ionization coefficients if the minimum current observed is 6 × 10–14A.

Q.8 Explain the manifestation of corona losses in transmission line system? Compare power loss due to corona in height and sea level.

## High Voltage Technology Questions  Past Papers 5

Time Allowed: 3 hours

Total Marks:    70, Passing Marks (35)

Q.1 Explain the manifestation of corona losses in transmission line system? Compare power loss due to corona at height and sea level.

Q.2 Explain briefly various theories of breakdown in liquid dielectrics.

Q.3 a) Why we use high voltage (HV) and introduced HV problems
b) Explain the photo excitation and collision ionization process for breakdown in dielectric material

Q.4 Explain Cockroft-Walton voltage multiplier circuit for high voltage DC generation with the help of neat sketches

Q.5 Explain any two methods of High Voltage Measurement with the help of figures

Q.6 List the causes of over voltage? What is lightening stroke to the ground. Explain the mechanism of lightening stroke.

Q.7 A steady current of 600 µA flows through the plane electrode separated by a distance of 0.5 cm when a voltage of 10 kV is applied. Determine the Townsend’s first ionization coefficient if a current of 60 µA flows when the distance of separation is reduced to 0.1 cm and the field is kept constant at the previous value. Determine the value for second ionization coefficients if the minimum current observed is 6 × 10–14A

Q.8 Write a note on any TWO of the following topics
a) Insulation coordination
b) High voltage testing of Cables
c) High Voltage Impulse Generation

## High Voltage Technology Questions  Past Papers 6

Time Allowed: 3 hours

Total Marks:    70, Passing Marks (35)

Q.1 Discuss various factors which affect breakdown of gases. Define Townsend’s first and second ionization coefficients. Explain the Townsends criterion for a spark.

Q.2 Explain briefly various theories of breakdown in solid dielectrics.

Q.3 a) Why we use high voltage (HV) and introduced HV problems
b) Explain the photo excitation and collision ionization process for breakdown in dielectric material

Q.4 Explain Cockroft-Walton voltage multiplier circuit for high voltage DC generation with the help of neat sketches

Q.5 What are the sources of liquid dielectric contamination? State various processes which lead to formation of bubbles in liquid dielectrics and explain clearly cavity breakdown mechanism in liquid dielectrics.

Q.6 Explain the procedure of high voltage test on transformer bushings and cable

Q.7 A 3-phase, 220 kV, 50 Hz transmission line consists of 1•5 cm radius conductor arranged in equilateral triangular fashion with line spacing of 6cm. If the temperature is 40ºC and atmospheric pressure is 76 cm, calculate the corona loss per km of the line. Take mo= 0•85

Q.8 Write a notes on any two of the following
a) Problems caused by corona discharge in transmission lines
b) Over voltage due to switching surges
c) Streamer breakdown

Prof.Fazal Rehman Shamil (Available for Professional Discussions)
1. Message on Facebook page for discussions,