STUPIDSID
1 (a)
A steady current of 600μA flows through the plane electrodes separated by a distance of 0.5cm when a voltage of 10kV is applied. Determine the Townsend's first ionization constant (coefficient) if a current of 60μA flows when the distance of separation is reduced to 0.1 cm and the field is kept constant at previous value.
7 M
1 (b)
Explain the difference between photo-ionization and photo-electric emission.
7 M
2 (a)
What is Vacuum? Discuss the various mechanisms of vacuum breakdown.
7 M
Answer any two question from Q2 (b) or Q2 (c)
2 (b)
Why are both electrical & thermal properties important for liquids for use in an apparatus like a transformer?
7 M
2 (c)
What is 'stressed oil volume theory', how does it explain breakdown in large volumes of commercial liquid dielectrics?
7 M
Answer any two question from Q3 (a), (b) or Q3 (c), (d)
3 (a)
What are the different methods and means for purification of liquid dielectric?
7 M
3 (b)
Discuss the different methods of measuring high dc voltages. What are the limitations in each method?
7 M
3 (c)
What is capacitance voltage transformer? Explain with phasor diagram how a tuned capacitance voltage transformer can be used for voltage measurements in power systems.
7 M
3 (d)
What is a trigatron gap? Explain its function and operation.
7 M
Answer any two question from Q4 (a), (b) or Q4 (c), (d)
4 (a)
For a High voltage D.C. generator using Cockroft-Walton circuit with 4 stages and peak input A.C. voltage of 100kV, 200Hz, the load current of 4mA and each stage capacitance of 0.02μF, calculate the ripple voltage and voltage drop.
7 M
4 (b)
What is the principle of operation of a resonant transformer? How is it advantages over the Cascade connected transformer?
7 M
4 (c)
Compare the use of uniform field electrode spark gap & sphere gap for measuring peak values of voltage.
7 M
4 (d)
Explain one method of controlled tripping of impulse generators. Why is controlled tripping necessary?
7 M
Answer any two question from Q5 (a), (b) or Q5 (c), (d)
5 (a)
Give the Marx circuit arrangement for multistage impulse generators. How is the basic arrangement modified to accommodate the wave time control resistance?
7 M
5 (b)
Define the following terms.
i) Corona Discharge
ii) Loss tangent
iii) Impulse ratio
iv) Partial discharge
v) Surge impedance
vi) Dielectric strength
vii) Townsend's first ionization constant.
i) Corona Discharge
ii) Loss tangent
iii) Impulse ratio
iv) Partial discharge
v) Surge impedance
vi) Dielectric strength
vii) Townsend's first ionization constant.
7 M
5 (c)
Write short notes on: (i) Type test (ii) Routine test
7 M
5 (d)
Explain in details the H.V Schering bridge. How is it different from low voltage Schering- bridge?
7 M
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