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E1108 Pages: 3

(i) The line voltage and

(ii) The string efficiency
What are the advantages and disadvantages of HVDC transmission systems?
Derive Kelvin’s law for conductors
What are the advantages of bundling of conductors?
PART D

Answer any two full questions, each carries 10 marks.
In a short circuit test on a 132kV three phase system, the breaker gave the
following result: power factor of the fault =0.6, recovery voltage 0.97of full
line value; the breaking current is symmetrical and the restriking transient had
a natural frequency of 16kHz. Determine the rate of rise of restriking voltage.
Assume that the fault is grounded.
Derive the equations for voltage drop and current loss in a two wire ring main
distributor supplied by (1) DC and (ii) AC Voltages.
With a neat sketch explain the principle of operation of an Air Blast Circuit
Breaker
What are the primary causes of over voltages? How are the equipments
protected from over voltages?
Explain the principle of operation of a static over current relay.
What are the three main protection aspects included in the protection of

alternators? Why are they significant?

بد بد ‎ಸಸ್ಯ‏

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