Download GTU B.Tech 2020 Winter 8th Sem 2180911 Power Quality And Management Question Paper

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GUJARAT TECHNOLOGICAL UNIVERSITY
BE- SEMESTER-VIII (NEW) EXAMINATION — WINTER 2020

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Subject Code:2180911 Date:19/01/2021
Subject Name:Power Quality And Management
Time:02:00 PM TO 04:00 PM Total Marks: 56

Instructions:

1. Attempt any FOUR questions out of EIGHT questions.

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2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.

MARKS

Q.1 (a) What are the effects of EMI on health? Enlist them. 03
(b) Explain displacement power factor and true power factor with necessary equation. 04

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(c) Explain various power quality issues due to distributed generation. 07

Q.2 (a) What is THD? According to IEEE 519, state various voltage and current THD? 03
(b) Explain the Power Quality Issues: Voltage Sag and Swell with suitable example. 04
(c) Explain the types and causes of the transients in electrical circuits. 07

Q.3 (a) What is grounding and bonding? How do they effect on electrical and electronics circuits? 03

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(b) Write the various shock hazards for 100 µA, 1-5 mA, 5-10 mA and 10-20 mA, 30 mA on Human body. 04
(c) Explain earth resistance test as per NEC code. 07

Q.4 (a) Draw the earth resistance Vs distance graph and write its importance. 03
(b) Explain the electric shock hazards with necessary diagram when the electric motor is not grounded. 04
(c) Write a short note on : Signal Reference Ground. 07

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Q.5 (a) What is harmonics? Explain with necessary waveforms. 03
(b) Write a short note on TDD. 04
(c) Enlist the various EMI mitigation methods. Explain anyone in detail. 07

Q.6 (a) When do we record harmonic signature? How does it help for health of the electrical equipments? 03
(b) What are the major sources of current harmonics? 04

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(c) Explain improvement in power factor using static VAR compensator. 07

Q.7 (a) How do you select the measurement tools and location for the power quality issues? 03
(b) Find out apparent power, active power, reactive power and power factor for:
v(t) = v2 x 230 sin(?t) + v2 x 50 sin(3?t — 30°)
i(t) = 2+ v2 x 10 sin(?t — 30°) + v2 x 5 sin(3?t — 60°) 04

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(c) What is “k rating” and “derating factor” of a transformer? Find the transformer derating factor for: A transformer with a full load current rating of 1200 A is subjected to a load with nonlinear characteristics having a total stray current loss density of 10% (0.1 pu). 07

Harmonic number (h) th (pu)
1 1
3 0.38
5 0.19

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7 0.11
9 0.06

Q.8 (a) What is the role of data loggers and chart recorders in case of measurement of power quality? 03
(b) What are issues with interfacing of the distributed generations? Enlist them. 04
(c) Explain the effects of harmonics on capacitor banks. 07

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