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45811 Pages: 2

PART C
Answer any two full questions, each carries 10 marks
An overhead line has a span of 122m, the diameter of the conductor is 1.15 cm.
Calculate the sag at mid span when the conductors have an ice coating of 0.96 cm
thick and the wind pressure is 382 N/m? of projected area. The weight of
conductor is 5.83 N/m, ice weighs 8920 N/m’ and the permissible tension is 3.56
x 10714.
A string has five suspension discs. The capacitance between each unit and earth is
one-fifth of the mutual capacitance:
i) Find the voltages across different discs as percent of total string voltage
ii) Find the string efficiency.
Differentiate between disruptive critical voltage and visual critical voltage.
What are the factors affecting corona?
Explain the working of any two FACTS devices.
What are the advantages of ‏ع0‎ transmission over ac transmission?
Explain the different types of ‏عل‎ links.
A 2.2 km long, 11 kV, 3 phase, 3 - core, belted cable gave the following results in
a test for capacitance:
Capacitance between two conductors joined to sheath and the third conductor is
1.5uF and capacitance between all the three conductors joined and sheath is1.8
uF, Find:
i) Effective capacitance of each core to neutral and
ii) Capacitance between any two cores
PART D
Answer any two full questions, each carries 10 marks
With the help of a diagram, explain the working of a vacuum circuit breaker.
With the help of a block diagram, explain the working of a static over current
relay.
With the help of a diagram, explain the working of a watt hour meter type
electromagnetic relay.
With the help of a neat diagram, explain the working of a Buchholz Relay
With the help of a diagram, explain the working of a surge diverter.
A single-phase a. ൦. distributor AB is fed from end A and has a total impedance of
(0.2 + j3) ൨. At the far end, the voltage Vz = 240۷ and the current is 100 A at a
power factor of 0.8 lagging. At the midpoint M, a current of 100 A is tapped at a
power factor of 0.6 lagging with reference to the voltage ‏يرلا‎ at the midpoint.
Calculate the supply voltage ۷۸ and phase angle between ۷۸ and Vg.

د عد ‎मं‏ عد

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