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The document is an examination paper for the Electrical Engineering Department at Sana'a University, focusing on transmission and distribution systems. It includes questions on designing a radial distribution system for a factory, drawing a 12-pulse HVDC link, reactive compensation, advantages of interconnected systems, and reasons for specific transmission system recommendations. The exam covers both theoretical and practical aspects of electrical engineering concepts relevant to distribution systems.

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Zayed ALariqi
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20 views1 page

Null 25

The document is an examination paper for the Electrical Engineering Department at Sana'a University, focusing on transmission and distribution systems. It includes questions on designing a radial distribution system for a factory, drawing a 12-pulse HVDC link, reactive compensation, advantages of interconnected systems, and reasons for specific transmission system recommendations. The exam covers both theoretical and practical aspects of electrical engineering concepts relevant to distribution systems.

Uploaded by

Zayed ALariqi
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF, TXT or read online on Scribd
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Sana’a University Transmission & distribution system

Electrical Eng. Department Final Examination 2000/2001


Final Year – Second term Time : 2 Hours

ANSWER ALL QUESTIONS

Q (1):
Design a radial distribution system for the following small factory. The load consists of:
- 4 motors each of 415 Volts and 0.5 MVA.
- 900 watt, 415 Volts and 0.90 power factor office loads (computer and lights).
Supply available is 33 kV at 750 MVA fault level infeed.
Following table may help you

Table (1) Available transformers rating


kV MVA Impedance
33/11 kV 5, 7.5, 24, 38 MVA 10% on rating
11/0.415 kV 300, 500, 750, 100 kVA !0% on rating

Available circuit breakers MVA fault levels


Voltage level MVA fault level
33 kV 1000, 1500 MVA
11 kV 250,350 MVA
415 Volt 31 MVA

Q (2):
(a) Draw a 12-pulse HVDC link. Show the main parts.
(b) Draw the basic circuit for the harmonic filter and explain it’s principle of work.

Q (3):

(a) When reactive compensation should be used? Explain in detail.


(b) What are the advantages of the interconnected system?

Q (4):
Give reasons for the following:-
(a) Under ground DC transmission system is recommended for submarine.
(b) DC lines are difficult to tap.
(c) Two transformers one Y/Y and other ∇/Y is used on each side of the HVDC link.
(d) Base load is supplied by the cheapest and the most efficient generation unit.
(e) Ring distribution feeders is more reliable than radial feeder.
(f) Fault level is the most important technical factor that should be considered when designing a
distribution system to feed motors.

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