Download GTU (Gujarat Technological University Ahmedabad) B.Tech/BE (Bachelor of Technology/ Bachelor of Engineering) 2020 Summer 6th Sem 2160904 High Voltage Engineering Previous Question Paper
Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE - SEMESTER? VI EXAMINATION ? SUMMER 2020
Subject Code: 2160904 Date:27/10/2020
Subject Name: HIGH VOLTAGE ENGINEERING
Time: 10:30 AM TO 01:00 PM Total Marks: 70
Instructions:
1. Attempt all questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
MARKS
Q.1 (a) Discuss the various mechanisms of vacuum breakdown.
03
(b) What is Paschen's law? Explicate minimum voltage for breakdown under
04
a given `pd' condition
(c) Define first ionization and second ionization coefficients of Townsend's
07
theory. Derive expression for current growth equation and state criteria
for breakdown.
Q.2 (a) Explain the phenomena of electrical conduction in liquid. How does it
03
defer from the gases?
(b) Discuss the effect of the following parameters on the breakdown of
04
liquids
1. Hydrostatic pressure
2. Solid impurities
3. Moisture content in oil.
(c) List the various mechanism of liquid dielectric used in high voltage
07
engineering. Explain stressed oil Volume theory in detail.
OR
(c) In experiment for determining the breakdown strength of transformer
07
oil, the following observations were made. Determine the power low
dependence between the gap spacing and the applied voltage of the oil.
Gap spacing
4
6
10
12
(mm)
Breakdown
90
140
210
225
voltage(KV)
Q.3 (a) List out the generation of HVDC. Explain half wave and full wave
03
rectifier circuit for generation HVDC.
(b) List the method used for generation of High Voltage AC. Explain HVAC
04
generation using resonant transformer.
(c) An impulse generator has 8 stages with each condenser rated for 0.16
07
F and 125 KV. The value of load capacitor is 1000 pF. Find for the
series resistance and damping resistance needed to produce 1.2 /50 s
Impulse wave. What is the maximum output voltage of the generator, if
the charging voltage is 120 KV
OR
Q.3 (a) Explain front and tail times of an impulse wave with neat sketch.
03
(b) What is trigatron gap? Explain its function and operation.
04
(c) Describe the method used for generation of multi level high voltage
07
impulse generation with neat diagram.
Q.4 (a) Compare the relative advantages of following methods for measurement
03
of HVDC.
1
1. Series resistance micrometer
2. Potential divider with electrostatic voltmeter.
(b) Discuss the different methods of measuring of high voltage d.c. What
04
are the limitations of each method?
(c) Explain the sphere gap method for measurement of peak value of
07
voltages. List and explain parameters affecting the measurement.
OR
Q.4 (a) Explain treeing and tracking related to solid breakdown.
03
(b) List out the Difference between Uniform field and Non-uniform field.
04
(c) Explain High voltage Schering bridge for tan and capacitance
07
measurement of Insulators.
Q.5 (a) What is surge arrester? How it used as shunt protective device
03
(b) Draw & confer Equivalent circuit of partial discharge.
04
(c) Explain the different theory for charge formation in clouds.
07
OR
Q.5 (a) List out the common test facilities available in High Voltage Lab. Explain
03
safety measures required for High Voltage Laboratory.
(b) Discuss power frequency tests of insulator
04
(c) Explicate insulation coordination and statistical approach to it.
07
*************
2
This post was last modified on 04 March 2021