code no: high voltage engineering - padhle.com · impulse generator circuits. [7] 5 a) ... explain...

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IV B.Tech I Semester Regular/Supplementary Examinations, Nov/Dec - 2014

HIGH VOLTAGE ENGINEERING

(Electrical and Electronics Engineering)

Time: 3 hours Max. Marks: 75

Answer any FIVE Questions

All Questions carry equal marks

*****

1 a) What is meant by Electric field stress? Briefly explain the estimation and

control of electric stresses.

[8]

b) Explain briefly the Charge Simulation Method for electric field computation in

multi-dielectric materials.

[7]

2 a) Explain various Ionization processes in gaseous dielectrics. [8]

b) What are commercial liquid dielectrics? How they differ from pure liquid

dielectrics and also give the examples of each type.

[7]

3 a) Explain the mechanisms of breakdown in composite dielectrics. [8]

b) Explain how the transformer insulation is divided and list the insulating

materials chosen for insulation.

[7]

4 a) With neat diagrams, explain the operation of rectifier circuits for producing

high DC voltages.

[8]

b) Define wave front time and wave tail time. Explain how these are controlled in

impulse generator circuits.

[7]

5 a) Explain the construction and principle of electrostatic voltmeter for

measurement of high AC voltages.

[8]

b) Explain about the different types of resistive shunts for impulse current

measurements.

[7]

6 a) With neat sketches, explain about three terminal cell for solids and liquids. [8]

b) Discuss about the terms used in partial discharge phenomenon.

[7]

7 a) Define the terms i) Loss factor ii) 50% Flashover voltage

iii) Impulse voltage iv) Creepage distance

[8]

b) With a schematic diagram, explain the method of measurement of Radio

Interference Voltage.

[7]

8 a) Explain the working principle of Electrostatic precipitator with a neat diagram

and give its merits.

[8]

b) Explain how the Electrostatic coating is done using high voltages. [7]

Code No: R41022 Set No. 1 R10

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*****

1 a) Briefly explain the four steps involved in Finite Element Method for electric

field computation.

[8]

b) Discuss the relative advantages and disadvantages of various numerical

methods for electric field computation.

[7]

2 a) Define Townsend’s first and second Ionization coefficients. Explain

Townsend’s criterion for breakdown.

[8]

b) Explain about the characteristics of liquid dielectrics.

[7]

3 a) Explain how treeing and tracking leads to breakdown in solid insulating

materials.

[8]

b) Discuss about the various insulating materials used for high voltage machines.

[7]

4 a) Derive the expressions for voltage ripple and regulation in a voltage multiplier

circuit.

[8]

b) Determine the ripple voltage and regulation of a 10 stage Cockroft-Walton DC

voltage multiplier circuit having a stage capacitance of 0.01 µF, supply voltage

100 kV at a frequency of 400 Hz and a load current of 10 mA.

[7]

5 a) Explain about various methods of high DC voltage measurements. Compare

the advantages of each type.

[8]

b) With neat diagram, explain about the sphere gap measurement of high impulse

voltages.

[7]

6 a) Discuss about DC galvanometer arrangement for resistivity measurements. [8]

b) Briefly explain how partial discharges in an insulation system can be detected

and displayed.

[7]

7 a) Explain about the Power frequency and Impulse tests done on insulators. [8]

b) Discuss about the synthetic testing procedure on HVDC valve units.

[7]

8 a) With neat schematic diagram, explain the working principle of Electrostatic

separator.

[8]

b) Explain how the Electrostatic copying is done using high voltages. [7]


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*****

1 a) What is Boundary Element Method? How does it differ from Charge

Simulation Method?

[8]

b) Define surge voltages. Explain how they are distributed in the windings of

power apparatus.

[7]

2 a) What is Paschen’s Law? How do you account for minimum voltage for

breakdown under given p x d condition?

[8]

b) Explain the various mechanisms of breakdown pheonomenon in commercial

liquids.

[7]

3 a) What is meant by Intrinsic strength? Explain Intrinsic breakdown mechanism

in solid dielectrics.

[8]

b) Discuss about the solid dielectrics applications in power cables and high

voltage bushings.

[7]

4 a) Explain about the cascade connection of transformers for producing high AC

voltages.

[8]

b) Explain about tripping and control of impulse generators.

[7]

5 a) With neat sketch, explain about the series capacitor peak voltmeter for the

measurement of peak values of AC voltages.

[8]

b) Explain about the resistance potential dividers for DC voltage measurements.

[7]

6 a) Define relative permittivity and loss factor. Also explain the factors that govern

these quantities.

[8]

b) Discuss about balanced detection method for partial discharge measurement.

[7]

7 a) Explain the Power frequency tests and Impulse voltage tests on bushings. [8]

b) Discuss about the six pulse back-to-back test on HVDC valve unit.

[7]

8 a) Briefly explain various industrial applications to high voltage engineering. [8]

b) Mention the industrial applications of high energy pulsed power generator. [7]


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*****

1 a) Briefly explain various numerical methods for estimation of electric field in

dielectric materials.

[8]

b) Explain how the electric field stress is controlled in dielectric materials.

[7]

2 a) Explain about the collision processes in gaseous dielectrics. [8]

b) Explain about the conduction and breakdown in pure liquids.

[7]

3 a) Explain about the different types of solid dielectrics used in practice. [8]

b) Discuss the insulation requirements for power capacitors.

[7]

4 a) Explain about the Tesla coil for generation of high frequency AC voltages. [8]

b) What is trigatron gap? Explain its functions and operation.

[7]

5 a) Describe the principle of operation of generating voltmeters for measurement

of high DC voltages. What are its advantages and limitations?

[8]

b) What is meant by potential divider? How it is used for impulse voltage

measurements.

[7]

6 a) With neat sketch, describe about high voltage Schering bridge for measurement

of insulator capacitance.

[8]

b) Explain how a fault position in a long cable can be located using partial

discharge technique.

[7]

7 a) Explain the impulse testing of high voltage transformers. [8]

b) Briefly explain the testing of surge arrestors.

[7]

8 a) Explain the working principle of Electrostatic precipitator. [8]

b) Explain how an electrostatic photo copier works. [7]


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code no: high voltage engineering - padhle.com · impulse generator circuits. [7] 5 a) ... explain...

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