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Seat No.: Enrolment
GUJARAT TECHNOLOGICAL UNIVERSITY
PDDC SEMESTER VI- EXAMINATION SUMMER 2017
Subject Code: X60904 Date: 06/05/2017
Subject Name: Power System Practice and Design
Time: 10.30AM to 01.00PM Total Marks: 70
Instructions:
1. Attempt all questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
Q.1

Discuss Kelvin's law to find the most economical conductor size. What are the limitations of this law?
07

Write the list of equipments which are used in substation. Also write the importance of each equipment.
07
Q.2

What is string efficiency? How it can be improved?
07

What is Ferranti effect? When and how it become significant? Explain methods to reduce it.
07
OR

Write a short note on Gas Insulated Substation (GIS).
07
Q.3

Explain the advantages and disadvantages of HVDC system.
07

What are corona losses? Discuss its significance and permissible limit. Write the advantages and disadvantages of corona losses.
07
OR
Q.3

Explain the various types of distribution systems.
07

Explain insulation co-ordination with curves.
07
Q.4

Explain measurement of earth resistance.
07

Define surge impedance loading. Explain the significant of it in transmission line design.
07
OR
Q.4

Discuss methods of reducing tower footing resistance.
07

Compare the design approach of short and medium transmission line.
07
Q.5

Write note on lamp flicker.
07

Derive equation to calculate sag in a transmission line with support at equal level.
07
OR
Q.5

What is skin effect? Explain in detail the significance of skin effect.
07

Prepare a layout of a typical 400 KV substation.
07