Categories: 8th Semester

1

Seat No.: ________ Enrolment No.___________

GUJARAT TECHNOLOGICAL UNIVERSITY

BE – SEMESTER ?VIII (old) – EXAMINATION ? SUMMER 2018

Subject Code:180903 Date:02/05/2018

Subject Name:Power System Practice and Design

Time:10:30 AM to 01:00 PM Total Marks: 70

Instructions:

1. Attempt all questions.

2. Make suitable assumptions wherever necessary.

3. Figures to the right indicate full marks.

Q.1 (a) Discuss classification of distribution systems with neat diagrams. What are the

advantages and dis-advantages of each?

07

(b) Enlist the steps to be followed for the construction of receiving end and

sending end power circle diagram. How the losses are determined from

receiving end diagram?

07

Q.2 (a) Define critical disruptive voltage and visual critical voltage. How Corona los can

be determined? What is significance of Corona in the design of transmission

line?

07

(b) Determine ABCD constants and Regulation of 3-phase Transmission line

considering following data.

Power = 85,000 kW, p.f.= 0.9 lagging, Distance = 160 km, Voltage = 230 kV,

Spacing of conductors = 10.2 m , Resistance/km = 0.22 O, outer radius R = 0.827

cm, Self GMD =0.768 R.

07

OR

(b) A single phase a.c. distributor 500 m long has a total loop impedance of (0.02 +j0.04) O and is fed from one end at 250 V. It is loaded as under:

1. 50 A at unity power factor, 200 m from the feeding point.

2.100 A at 0.8 power factor lag, 300 m from the feeding point.

3. 50 A at 0.6 power factor lag, at the far end.

Calculate the total voltage drop in the distributor and the voltage at the far end.

07

Q.3 (a) State and explain Kelvin?s law for the most economical cross section of

conductor.

07

(b) The cost of two core feeder cable, including installation is (90a +10) per metre

& interest and depreciation charges are 15%. The cable 1 km in length and cost

of energy is 3 paisa per unit. Maximum current in the feeder is 260 A and

demand is such that copper loss is equivalent to that would be produced by full

current flowing for 6 months. If resistance of conductor of 1 sq. cm. and 1 km

length is 0.173 ohm. Calculate most economical cross sectional area.

07

OR

Q.3 (a) What is lamp flicker? What are its causes? What type of loads are responsible for

it? How can it be reduced?

07

(b) Explain the steps involve in the lightning arrestor selection. Highlight the effect of

earthling for selecting voltage rating of the arrestor.

07

Q.4 (a) Define Insulation Coordination. Explain Insulation Co-ordination curves. 07

(b) What methods are adopted to reduce the tower footing resistance. 07

OR

Q.4 (a) What is stringing chart ? How the preliminary design of tower is carried out?

07

(b) Discuss applications of HVDC systems 07

Q.5 (a) Write a brief note on Gas Insulated Substation

07

(b) Explain the various types of DC link. Name some HVDC systems in India and its

Future.

07

1

Seat No.: ________ Enrolment No.___________

GUJARAT TECHNOLOGICAL UNIVERSITY

BE – SEMESTER ?VIII (old) – EXAMINATION ? SUMMER 2018

Subject Code:180903 Date:02/05/2018

Subject Name:Power System Practice and Design

Time:10:30 AM to 01:00 PM Total Marks: 70

Instructions:

1. Attempt all questions.

2. Make suitable assumptions wherever necessary.

3. Figures to the right indicate full marks.

Q.1 (a) Discuss classification of distribution systems with neat diagrams. What are the

advantages and dis-advantages of each?

07

(b) Enlist the steps to be followed for the construction of receiving end and

sending end power circle diagram. How the losses are determined from

receiving end diagram?

07

Q.2 (a) Define critical disruptive voltage and visual critical voltage. How Corona los can

be determined? What is significance of Corona in the design of transmission

line?

07

(b) Determine ABCD constants and Regulation of 3-phase Transmission line

considering following data.

Power = 85,000 kW, p.f.= 0.9 lagging, Distance = 160 km, Voltage = 230 kV,

Spacing of conductors = 10.2 m , Resistance/km = 0.22 O, outer radius R = 0.827

cm, Self GMD =0.768 R.

07

OR

(b) A single phase a.c. distributor 500 m long has a total loop impedance of (0.02 +j0.04) O and is fed from one end at 250 V. It is loaded as under:

1. 50 A at unity power factor, 200 m from the feeding point.

2.100 A at 0.8 power factor lag, 300 m from the feeding point.

3. 50 A at 0.6 power factor lag, at the far end.

Calculate the total voltage drop in the distributor and the voltage at the far end.

07

Q.3 (a) State and explain Kelvin?s law for the most economical cross section of

conductor.

07

(b) The cost of two core feeder cable, including installation is (90a +10) per metre

& interest and depreciation charges are 15%. The cable 1 km in length and cost

of energy is 3 paisa per unit. Maximum current in the feeder is 260 A and

demand is such that copper loss is equivalent to that would be produced by full

current flowing for 6 months. If resistance of conductor of 1 sq. cm. and 1 km

length is 0.173 ohm. Calculate most economical cross sectional area.

07

OR

Q.3 (a) What is lamp flicker? What are its causes? What type of loads are responsible for

it? How can it be reduced?

07

(b) Explain the steps involve in the lightning arrestor selection. Highlight the effect of

earthling for selecting voltage rating of the arrestor.

07

Q.4 (a) Define Insulation Coordination. Explain Insulation Co-ordination curves. 07

(b) What methods are adopted to reduce the tower footing resistance. 07

OR

Q.4 (a) What is stringing chart ? How the preliminary design of tower is carried out?

07

(b) Discuss applications of HVDC systems 07

Q.5 (a) Write a brief note on Gas Insulated Substation

07

(b) Explain the various types of DC link. Name some HVDC systems in India and its

Future.

07

2

OR

Q.5 (a) What are the limitations of HVAC transmission? Give the applications of HVDC

system.

07

(b) What is earth resistance ?Why its value should be as low as possible ?How it is

measured with voltmeter-ammeter method ?

07

*************

746268 PAPER V - REHABILITATION MEDICINE INCLUDING GERIATRIC MEDICINETHE TAMIL NADU DR. M.G.R. MEDICAL UNIVERSITY…

4 years ago

746268 PAPER V - REHABILITATION MEDICINE INCLUDING GERIATRIC MEDICINETHE TAMIL NADU DR. M.G.R. MEDICAL UNIVERSITY…

4 years ago

746267 PAPER IV - P.T. IN ORTHOPAEDICSTHE TAMIL NADU DR. M.G.R. MEDICAL UNIVERSITY [LN 6267]…

4 years ago

746267 PAPER IV - P.T. IN ORTHOPAEDICSTHE TAMIL NADU DR. M.G.R. MEDICAL UNIVERSITY [LN 6267]…

4 years ago

746266 PAPER III – CLINICAL ORTHOPAEDICSTHE TAMIL NADU DR. M.G.R. MEDICAL UNIVERSITY [LN 6266] AUGUST…

4 years ago

746265 PAPER II – P.T. IN NEUROLOGYTHE TAMIL NADU DR. M.G.R. MEDICAL UNIVERSITY [LN 6265]…

4 years ago