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A7011

Each line of a 3-phase system is suspended by a string of 3 similar insulators. If
the voltage across the line unit is 17.5 kV, calculate line to neutral voltage.
Assume that the shunt capacitance between each insulator and earth is 1/8" of the
capacitance of the insulator itself. Also find the string efficiency.
PART 0

Answer any twofull questions, each carries 10 marks.
Explain the Operation the Vacuum CB using a neat sketch and write its
advantages.
Explain any two types of Amplitude Comparators.
Explain Carrier — Current protection Scheme for long transmission lines.
Explain the characteristics features of Surge Diverters and explain any two types
of Surge Diverters.
Drive the Essential Qualities of Protective relays.
Explain using phasor diagram the directional feature of relays.
A 2 wire de ring distributor is 300m long and is fed at 240V at point A. At point
B, 150m from A, a load of 120A is taken and at C, 100m in the opposite
direction from A, a load of 80A is taken. If the resistance per 100m of single
conductor is 0.03Q find:

i)Current in each section of distributor = ii) Voltage at points 8 and ಲೆ,
11,

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