03000EE369092001 Pages: 3

Reg No.: Name:
APJ ABDUL KALAM TECHNOLOGICAL UNIVERSITY

Fifth semester B.Tech degree examinations (S) September 2020

Course Code:EE369
Course Name: HIGH VOLTAGE ENGINEERING
Max. Marks: 100 Duration: 3 Hours
PARTA

Answer all questions, each carries 5 marks. Marks
1 Using the first principles, explain the operation of a Van de Graff generator. (5)
2 Outline the principle of operation of a resonant transformer? (5)
3 Sketch the circuit for (i) switching impulse voltage of short duration (ii) switching (5)

impulse voltage of long duration.

4 Explain two methods of measuring impulse current. (5)
Explain the method of measuring the RIV in a power apparatus. (5)
6 Define the following terms:- Partial discharge, Discharge inception voltage, (5)

Discharge extinction voltage, Discharge magnitude, Quadratic rate.

7 Write a note on the classification of High voltage laboratory. (5)
8 Explain one power frequency test and one impulse voltage test on Bushings (5)
PART ‏جا‎

Answer any two full questions, each carries 10 marks.
9 a) Deduce the expression for ripple voltage and voltage regulation in a Cockcroft (6)
Walton voltage multiplier circuit.

b) Determine the % ripple voltage of a 8 stage cockroft Walton voltage multiplier (4)
circuit having a stage capacitance of 0.05micro F. The supply voltage is 125kV at a
frequency of 150Hz and a load current of 1.5 mA. Also find the optimum number
of stages and maximum output voltage.

10 a) State why a cascade transformer is used in HV AC power frequency testing. (6)
Elucidate the working of a 3-stage cascade transformer with a neat sketch. Label
the power rating of the various stages of the transformer in the above circuit.
b) Derive the equivalent impedance expression for the cascade transformer. (4)
11 a) How are high frequency, high ac voltages with damped oscillations produced? (5)
State its application.

b) A cable test unit is required to test cables at 500kV. The testing transformer (5)

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