# Peak Value of Critical Surface

### Question:

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1: (2.5 marks)
Explain why it is not possible to totally eliminate corona loss in a power line or reduce it absolutely to zero.

2: (5 marks)
Explain advantages of HVDC transmission lines from the viewpoint of Corona effect and loss, compared to those of HVAC transmission lines.

3: (5 marks)
A 3-phase ac overhead transmission line has equivalent spacing of 5.5 m between conductors and each conductor has diameter of 3 cm. Atmospheric temperature is 12 deg C, and barometric pressure of 750 mm of Hg. The surface irregularity factor for the stranded conductor is 0.9.

Determine the Peak value of Critical Surface stress for fair weather and visual corona for center conductor.

4: (5 marks)
Discuss the steps taken by the government of Australia or your country to increase efficiency in the field of energy.

5: (2.5 marks)
Consider a circular coil of radius 8 cm and having 24 turns. A current of 1 A is passed through the coil. Find the magnetic field at a point on the axial line, which is at a distance of 14 cm from the center of the coil.

6: (5 marks)
The German government intends to generate 35% of its power needs from renewables by 2020, and reduce energy consumption by 20% over this period. Highlight some of the developments and revolutionising ideas adopted by Germany to achieve this goal in order to promote clean energy concept.