LAXMI INSTITUTE OF TECHNOLOGY, SARIGAM · 2019. 3. 4. · Explain setting of relays. 3f. Describe...

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SWITCHGEAR AND PROTECTION 3360901

GTU/ NITTTR Bhopal/14-15 Gujarat State

GUJARAT TECHNOLOGICAL UNIVERSITY, AHMEDABAD, GUJARAT

COURSE CURRICULUM

COURSE TITLE: SWITCHGEAR AND PROTECTION

(COURSE CODE: 3360901)

Diploma Programme in which this course is offered

Semester in which offered

ELECTRICAL ENGINEERING DEPARTMENT

SIXTH

1. RATIONALE

An electrical power system consists of generators, transformers, and transmission and

distribution lines. In case of fault, an automatic protective scheme comprising of circuit

breakers and protective relays isolate the faulty section providing protection to the healthy

section. Safety of machines/equipment and human beings is the major criteria of every

protection scheme. It is essential that the diploma pass out students should develop skills of

operating various controls and switchgear in power system. They are required to carry out

remedial measures for faults/abnormalities in machines/equipment in power system using

appropriate diagnostic instrument/devices.

2. COMPETENCY

The course content should be taught and implemented with the aim to develop different types of

skills so that students are able to acquire following competency:

Maintain various controls and switchgear in power system

3. COURSE OUTCOMES:

Student will be able to:

i. Identify various types of faults in Power system

ii. Maintain different types of circuit breakers in power system.

iii. Maintain different types of relays in power system.

iv. Protect transmission line and feeder from various faults

v. Protect transformer, alternator, motor and busbar

vi. Protect power system against over voltages

4. Teaching and Examination Scheme

Teaching Scheme

(In Hours)

Total

Credits

(L+T+P)

Examination Scheme

Theory Marks Practical

Marks

Total

Marks

L T P C ESE PA ESE PA

150 4 0 2 6 70 30 20 30



Legends: L-Lecture; T – Tutorial/Teacher Guided Theory Practice; P -Practical; C – Credit ESE -End Semester

Examination; PA - Progressive Assessment.

5. COURSE DETAILS

Unit Major Learning

Outcomes

Topics and Sub-topics

Unit – I.

Elements of

protection

1a Describe the function

of basic elements of a

protective system

1b State various types of

faults and

abnormalities

occurring in a power

system.

1c Describe the operation

of the Backup

protection

1d Explain the use of

Current Transformer.

and Potential

Transformer in

protection system.

1e Explain various

methods of neutral

Earthing.

1.1 Need of protective system

1.2 Functions of basic elements of a

protective system.

1.3 Basic functional characteristics of

protection system

1.4 Types, causes and effects of

various Faults.

1.5 Protection zones

1.6 Backup protection & its types.

1.7 Necessity of Protective

Transformers

1.8 Specifications and Connection

diagram of Current Transformer

and Potential Transformer both

single and 3 phase

1.9 Use of current limiting reactors

and their arrangements.

1.10 Importance and methods of

neutral Earthing



Unit Major Learning

Outcomes


Unit– II

Circuit Interrupting

Devices

2a. Draw line diagram

of a protective system

showing different

circuit interrupting

devices

2b. Explain the

sequence of operation

of and interlocking of

the above devices

2c. Explain the terms

associated with fuse

and circuit breaker

2d. Explain

characteristics of fuse

and circuit breakers.

2e. Explain arc

formation and zero

current interruption.

2f. Compare arc

quenching in A.C. &

D.C. Circuit Breaker

2g. Explain the

resistance switching

2h. Describe the

Sequence of operation

of circuit breaker.

2.1 Necessity and types of interrupting

devices

2.2 Sequence of operation and

interlocking

2.3 Fuse, types, terms related to fuse,

characteristics, testing and

applications

2.4 Requirement and types of

isolators.

2.5 Arc phenomena and arc extinction

in circuit breaker

2.6 Important terms associated with

circuit Breaker

2.7 Resistance switching

2.8 Construction, working principle of

Air break, Air Blast, Sulphur Hexa

Fluoride (SF6 ) and vacuum circuit

breakers.

2.9 Circuit breaker ratings

2.10 Auto-reclosure

2.11 Testing of circuit breaker

2.12 Working principle of arc

quenching in HVDC circuit

breaker

Unit– III

Protective relays

3a. Explain the

classification and

application of relays.

3b. State the basic

terms related to relays.

3c. Explain the

working of different

types of relays.

3d. Explain concept of

over current and

directional relays.

3e. Explain setting of

relays.

3f. Describe the testing

procedure of various

relays.

3.1 Protective relay, classification

and selection

3.2 Basic terms related to relay -Pick

up value, reset value and operating

current etc.

3.3 Principle of working ,construction

and operation of electromagnetic

induction(shaded pole, watt-hour

meter and induction cup),Thermal

relay

3.4 Settings of various types of relays

3.5 Directional relay

3.6 Distance relay(impedance,

reactance and mho)

3.7 Negative phase sequence relay

3.8 Need of static relay, Construction

and types

3.9 Principle and working of

Microprocessor based relay

3.10 Maintenance and testing of relays



Unit Major Learning

Outcomes


Unit–IV

Protection of

transmission line and

feeder

4a. Compare various

protection scheme

of transmission

line.

4b. Explain simple

Impedance relay

4c. Explain need of

carrier aided

protection.

4d. State the types of

auto reclosing.

4e. Explain protection

of feeders and

ring mains and Bus

bar

4.1 Need of transmission line

protection scheme

4.2 Selection of protection scheme -

Overload protection, Over-

current and earth fault protection,

Time graded and current graded

protection, Current balance

differential protection

4.3 Need of Carrier aided protection,

Carrier inter-tripping,

acceleration and blocking scheme

4.4 Distance /Impedance protection

4.5 Necessity and types of Auto

reclosing

4.6 Protection of parallel feeders and

Ring Mains

Unit-V

Protection of

transformer,

alternator, motor and

bus bar

5a. Explain various

protection scheme for

transformer.

5b. Describe the inrush

current phenomenon

in transformer.

5c. Explain the protection

offered by Buchholz

Relay

5.1 Over current, Percentage

differential and Restricted earth

fault protection of Transformers.

5.2 Inrush phenomenon and over

fluxing phenomenon in

Transformer.

5.3 Buchholz Relay, analysis of

trapped gases

5d. Explain the faults and

abnormalities in

alternator,

5e. Explain various faults

occurring in motor

and their protection

schemes.

5f. Explain Differential

protection of Busbars

5.4 Various faults and abnormal

operating conditions in

Alternator and its protection

schemes.

5.5 Various faults and abnormal

occurring in the Motor and its

protection schemes.

5.6 Differential Protection of Bus

bars.

Unit-VI

Over voltage

protection

6a. State the causes of

over voltage.

6b. Explain the

characteristics of

Lightning Arrestor.

6c. Describe the

Insulation co-

ordination and basic

impulse

insulationLevel

6.1 Causes of over voltages.

6.2 Methods of reducing over

voltages.

6.3 Operating principles,

construction and

Applications of lightning arrester

6.4 Insulation co-ordination, volt-

time characteristic and basic

impulse insulation level.



6. SUGGESTED SPECIFICATION TABLE WITH HOURS & MARKS (THEORY)

Unit

No.

Unit Title Teaching

Hours

Distribution of Theory Marks

R

Level

U

Level

A

Level

Total

Marks

I Elements of protection 08 04 02 02 08

II Protective relays 12 05 06 04 15 III Circuit interrupting devices 10 05 06 04 15 IV Protection of transmission line 12 04 08 03 15 V Protection of transformer, alternator,

motor & busbar 10 04 06 02

12

VI Over voltage protection 04 03 02 00 05

Total 56 25 30 15 70

Legends: R = Remembrance; U= Understanding; A= Application and above levels (Revised Bloom’s

taxonomy)

Note: This specification table shall be treated as a general guideline for students and teachers.

The actual distribution of marks in the question paper may vary slightly from above table.

7. SUGGESTED LIST OF EXERCISES/PRACTICALS

The practical/exercises should be properly designed and implemented with an attempt to

develop different types of cognitive and practical skills (Outcomes in cognitive, psychomotor

and affective domain) so that students are able to acquire the competencies.

Following is the list of practical exercises for guidance.

Note: Here only outcomes in psychomotor domain are listed as practical/exercises. However,

if these practical/exercises are completed appropriately, they would also lead to development

of Programme Outcomes/Course Outcomes inaffective domain as given in a common list at

the beginning of curriculum document for this programme. Faculty should refer to that common

list and should ensure that students also acquire those Programme Outcomes/Course Outcomes

related to affective domain

S. No. Unit

No.

Practical Exercises

(Outcomes’ in Psychomotor Domain) Hrs.

required

1 I Check the Polarity of Current Transformer and Potential

Transformer and connect it with the relay. 02

2 II Test overload relay and plot Time-Current characteristic 02

3 II Test Buchholz relay for transformer protection. 02

4 II Test thermal overload relay for protection of motor and set the

relay properly. 02

5 II Test static relay for the protection of motor 02

6 III Determine the fusing factor of a given fusing material. 02

7 III Test the performance of Vacuum circuit breaker. 02

8 III Test the performance of SF6 circuit breaker. 02

9 IV Apply balance current protection scheme using appropriate

switch gear 02

10 IV Interpret various protective scheme used for transmission lines

and feeders (from Blue print and visit). 04

11 IV Draw schematic diagram of protective schemes for 66 KV/ 132

KV/220 KV Substation nearby area. (after visit) 04

12 IV Visit a substation and prepare its technical report emphasizing on

control side 04



13 V Interpret the protection scheme for an alternator in power station

(from Blue print and visit). 04

14 V Interpret different protective scheme for transformer. 02

15 VI Demonstrate the performance of Horn gap lightning arrester. 02

Total 28

8. SUGGESTED LIST OF STUDENT ACTIVITIES

Following is the list of proposed student activities like:

i. Prepare chart for line diagram of power system

ii. Prepare chart of basic elements of protective system.

iii. List different types of relays, circuit breakers and collect literature from

dealers/Manufactures.

iv. Prepare display chart for various types of fuse.

v. Prepare the chart for Combined Earth Fault and Phase Fault Protective scheme.

vi. Download the video of functioning of HVDC circuit breaker, Lightning arrester.

SPECIAL INSTRUCTIONAL STRATEGIES (if any)

i. Show video/animation film to demonstrate the working principles, constructional

features, testing and maintenance of different types of relays and circuit breakers

ii. Arrange a visit to nearby manufacturer site of protection panel

iii. Arrange a visit to relay testing laboratory.

9. SUGGESTED LEARNING RESOURCES

A) List of Books

S.

No. Title of Book Author Publication

1. Fundamentals of Power

System Protection

Paithankar Y. G.and Bhide S. R PHI, New Delhi

(Latest Edition)

2. Power System Protection

and Switchgear

Ram B and Vishwakarma D. N. TMH, New Delhi

(Latest Edition)

3. Electrical Power Uppal S.L. Khanna Publications

(Latest Edition)

4.

Electrical Power System Mehta V. K. S. Chand

Publications

(Latest Edition)

5.

Switchgear and

Protection

Rao S. S. Khanna Publications,

New Delhi

(Latest Edition)

6. Electrical Power Systems Rao S. S and Uppal S. L Khanna Publications

(Latest Edition)

7. Switchgear and

Protection

Gupta J. B. Katariya

(Latest Edition)

8.

Power system Protection

and Switchgear

Ravindranath B. and M. Chander Wiley Eastern Ltd,

Delhi.

(Latest Edition)



9. Art and Science of

Protective relaying

Wadhwa. C. L. C.R.Mason, John

Wiley

B) List of Major Equipment/ Instrument with Broad Specifications

Numerical relay panel with all

protection

Time-overcurrent protection (definite-time/inverse-time/user-def.) , Sensitive earth-fault detection, Inrush restraint, Motor protection(Undercurrent monitoring, Starting time supervision, Locked rotor, Overload protection, Temperature monitoring, Load jam protection

Static earth fault relay

Ratings : 5 A , 50 Hz, VA rating : 3 VA typical Setting ranges : Low-set : 0.1 A to 5.0 High-set : 0.1 A to 50 A

VCB with operation simulation

panel

VCB along with variable earth leakage relay, Over

voltage / under voltage relay, loading facility, over / under

frequency relay, overload relay, to operate under various

abnormal conditions.

Panel for Biased Differential

protection of Transformer

•Test setup is equipped with single-phase type static relay

connected with single- phase auto transformer,provides

facility to vary current using a variac and rheostats.

B) List of Software/Learning Websites i. WWW.nptel.iitm.ac.in

10. COURSE CURRICULUM DEVELOPMENT COMMITTEE

Faculty Members from Polytechnics

Prof. S.V.Jagani, Government Polytechnic, Dahod

Prof. T. A. Patel, Government Polytechnic, Dahod

Prof. H. C. Chavda, R.C. Technical Institute, Ahmedabad

Coordinator and Faculty Members from NITTTR Bhopal

Dr. (Mrs.)C.S. Rajeshwari, Professor, Electrical and Electronics Engineering, NITTTR,

Bhopal

Prof.A.S. Walkey, Associate Professor, Electrical and Electronics Engineering,

NITTTR, Bhopal

http://www.nptel.iitm.ac.in/

Laxmi Institute of Technology, Sarigam

Diploma Electrical Engineering Department Academic Year: 2018-19

ASSIGNMENT: 1

Name of Subject : - SWITCHGEAR AND PROTECTION Date:

Subject Code : 3360901

Chapter/Unit 1: ELEMENT OF PROTECTION SYSTEM

Sr. No. Name of Question Remarks

1. Draw the block diagram of protection system and state the function of each block.

2. State the essential characteristics of the protective relaying system.

3. Define fault. State and explain types and causes of fault.

4. State and Explain primary and backup protection.

5. Explain the necessity of the protective transformer in the protective system.

6. Explain the comparison between C.T. & P.T..

7. Difference between the power transformer and & C.T..

8. Explain the term ‘ BURDEN ‘ in the CT ad draw the different connection of C.T. & P.T..

9. What is earthing? Explain different method of neutral earthing.

10. Explain Importance and advantages of neutral earthing.

11. Explain current limiting reactor & their arrangement.

Date of Submission:-

Name & Sign of Subject In-charge :



ASSIGNMENT: 2



Chapter/Unit 2: CIRCUIT INTERRUPTING DEVICES


1. Give the name of all circuit interrupting devices used in protection system also draw the symbol and Explain function of all.

2.

Define the following terms: 1) Arcing time 2) Cut off current 3) Fusing factor

4) Pre Arcing time 5) Recovery Voltage 6) Restriking Voltage 5) Rate of rise of voltage 6) Making Capacity 7) Breaking Capacity 8) Symmetrical Breaking Capacity

3. Explain all type of HRC fuse and also state advantages and disadvantages of it.

4. List different type of isolators and Explain vertical pantograph isolator.

5. Explain Air Blast Circuit Breaker.

6. Explain SF6 Circuit Breaker.

7. Compare Isolator & Circuit Breaker.

8. State and Explain different type of test performed on Circuit Breaker.






ASSIGNMENT: 3



Chapter/Unit 3: Protective relays


1. Explain the basic trip circuit of relay. Give the classification of relay.

2. Give the classification of electromagnetic relay. Explain construction and working principle of attracted armature type relay.

3.

Define the terms related to relay operation: (1)characteristic quantity (2) Error (3) pick up current (4) Plug setting multiplier (5) over reach (6)Rated burden (7) Rated dynamic current (8) Stability (9) Blocking. (10) Operating time (11) pick up value (12) PSM (13) burden (14) reach (15) time setting multiplier.

4. Explain the working principle and construction of Induction Cup type relay.

5.

An over current relay having current setting at125% and time setting multiplier of 0.6 is connected to a transformer through a CT of 400/5. If the fault current is 4000amp. and time from time-Psm curve is 3.5 second, then calculate PSM and actual time of operation of relay.

6. Explain the Resistance, Reactance and Mho type characteristic of Distance relay.

7. Describe directional over current relay using neat sketch .And differentiate between directional power relay and directional over current relay.

8. Explain impedance relay with its mathematical equation and operating characteristics.

9. Explain static relay & also its disadvantages / limitations and remedial measures to overcome them.

10. Draw the block diagram of microprocessor based over current relay and explain the function of each block.

11. Draw and explain the working of Buchholz Relay.

12. Explain the comparison of static versus Electromagnetic relay





ASSIGNMENT: 4



Chapter/Unit 4: Protection of transmission line and feeder


1. Explain differential over current protection .State difficulties arising in it and its remedial measures.

2. Explain the graded protection system for feeder.

3. Explain Distance & directional protection for transmission line.

4. Explain the protection of rings main.

5. Compare non unit type & unit type protection system for transmission line.

6. Explain carrier current protection scheme of transmission lines by necessary Block diagram.

7. Explain the zone protection of transmission Lines by Distance Relay.

8. Explain Translay relay with necessary diagram.





ASSIGNMENT: 5



Chapter/Unit 5: Protection of transformer, alternator, motor and bus bar


1. Explain biased differential protection for the three phase transformer with diagram. Also state the importance of harmonic restraint.

2. Explain the faults and abnormalities in power transformer. Explain differential protection of transformer.

3. List the abnormalities/fault occurring in the alternator. Discuss the effect.

4. Explain principle of differential protection and describe Merz-price protection scheme for an alternator and motor.

5. Describe protection of alternator against internal faults of stator winding using percentages biased differential relay.

6. Differentiate earth fault and restricted earth fault protection.

7. Explain the faults and abnormalities of Generator. Explain the Restricted Earth Fault Protection of Generator.

8. Explain protection of ring mains.

9. State and explain schemes for protection of motor.


11. Explain Frame leakage or Circulating current protection for busbar.





ASSIGNMENT: 6



Chapter/Unit 6 : Over voltage protection


1. Explain causes of Over Voltage.

2. Explain with diagram, construction and working of surge absorber.

3. Explain the function of Lightning Arrester. Explain the different types of Lightning Arrester.

4. Explain construction and working principle of Zinc –Oxide type lightening arrestor.

5. Draw and explain the expulsion type arrester along with advantages.

6. What do you mean by insulation coordination? Explain volt-time characteristics of standard impulse wave.



Laxmi Institute of Technology, Sarigam ELECTRICAL ENGINEERING DEPARTMENT

Year: 2018-19

Name of Subject : SWITCHGEAR & PROTECTION Date:

Subject Code : (3360901)

Chapter/Unit: 1


1. Draw the block diagram of protection system and state the function of each block.

2. State the essential characteristics of the protective relaying system.

3. Define fault. State and explain types and causes of fault.

4. State and Explain primary and backup protection.

5. explain the comparison between C.T. & P.T..

6. Difference between the power transformer and & C.T..

7. Explain the term ‘ BURDEN ‘ in the CT ad draw the different connection of C.T. & P.T..

8. What is earthing? Explain different method of neutral earthing.

9. Explain Importance and advantages of neutral earthing.

10. Explain current limiting reactor & their arrangement.




Year: 2018-19

Chapter/Unit: 2



2.

Define the following terms: Arcing time Cut off current Fusing factor Pre Arcing time Recovery Voltage Restriking Voltage Rate of rise of voltage Making Capacity Breaking Capacity Symmetrical Breaking Capacity

3. Explain all type of HRC fuse and also state advantages and disadvantages of it.

4.

Explain the difference between :3 1) Isolator & circuit breaker 2) Isolator & switch gear

5. Explain any two characteristic of HRC fuse ,How the characteristic is used for the protection scheme?

6. What is isolator ? List different type of isolators and Explain vertical pantograph isolator.

7.

Explain construction & working of: 1) Air Blast Circuit Breaker . 2) SF6 Circuit Breaker . 3) Vacuum Circuit Breaker . 4) Minimum oil Circuit Breaker .

8. Explain the arc interruption through related with Circuit Breaker .

9. State the advantages & disadvantages of SF6 gas in SF6 Circuit Breaker .




Year: 2018-19

Chapter/Unit: 3


1. Explain the basic trip circuit of relay. Give the classification of relay.

2. Give the classification of electromagnetic relay. Explain construction and working principle of attracted armature type relay.

3.

Define the terms related to relay operation: (1)characteristic quantity (2)error (3)pick up current (4)Plug setting multiplier ( 5)Over reach (6)Rated burden (7)Rated dynamic current (8) Stability (9) Blocking.(10) operating time (11) pick up value (12) PSM (13)burden (14) reach (15) time setting multiplier.

4. Explain the working principle and construction of Induction Cup type relay.

5.

An over current relay having current setting at 125% and time setting multiplier of 0.6 is connected to a transformer through a CT of 400/5. If the fault current is 4000amp. and time from time-PSM curve is 3.5 second, then calculate PSM and actual time of operation of relay.

6. An over current relay having current setting at 150% and TSM of 0.5 is connected to a transformer through a CT of 500/5. If the fault current is 6000 A. Find 1. Fault current in relay 2. Plug setting.

7. Explain the Resistance, Reactance and Mho type characteristic of Distance relay.

8. Describe directional over current relay using neat sketch .And differentiate between directional power relay and directional over current relay.

9. Explain impedance relay with its mathematical equation and operating characteristics.

10. Explain the operating current & pick up, time setting of relay.

11. Explain static relay & also its disadvantages / limitations and remedial measures to overcome them.

12. Draw the block diagram of microprocessor based over current relay and explain the function of each block.


14. Explain the comparison of static versus Electromagnetic relay

15. Write a short note on relay testing & maintenance .




Year: 2018-19

Chapter/Unit: 4


1. Give the difference between unit & non unit type protection.

2. Explain the voltage balance scheme for line unit with its advantages & limits.

3. Explain differential over current protection .State difficulties arising in it and its remedial measures.

4. Explain Distance protection for transmission line.

5. Explain carrier current protection scheme of transmission lines by necessary circuit diagram.

6. Explain the Ring main protection scheme.

7. Explain circulating current protection & Translay relay with necessary diagram.

8. Explain time & current graded protection for feeders.




Year: 2018-19

Chapter/Unit: 5


1. Explain biased differential protection for the three phase transformer with diagram. Also state the importance of harmonic restraint.

2. Explain the faults and abnormalities in power transformer. Explain differential protection of transformer.

3. List the abnormalities/fault occurring in the alternator. Discuss the effect.

4. Explain principle of differential protection and describe Merz-price protection scheme for an alternator and motor.

5. Justify the statement “ the CT should be connected in delta when transformer winding is connected in star and the CT should be connected in Star when transformer winding is connected in delta .”

6. Describe protection of alternator against internal faults of stator winding using percentages biased differential relay.

7. Differentiate earth fault and restricted earth fault protection.

8. Explain the faults and abnormalities of Generator. Explain the Restricted Earth Fault Protection of Generator.

9. Explain how protection given to the alternator against the failure of exciter.

10. State and explain schemes for protection of motor.

11. Write a short note on Bus Bar protection scheme.




Year: 2018-19

Chapter/Unit: 6


1. Explain causes of Over Voltage.

2. Explain with diagram, construction and working of surge absorber.

3. Explain the function of Lightning Arrester. Explain the different types of Lightning Arrester.

4. Explain construction and working principle of Zinc –Oxide type lightening arrestor.

5. Draw and explain the expulsion type arrester along with advantages.

6. What do you mean by insulation coordination? Explain volt-time characteristics of standard impulse wave.



Laxmi Institute of Technology, Sarigam Approved by AICTE, New Delhi; Affiliated to Gujarat Technological University, Ahmedabad

Academic Year 2018-19

Centre Code: 691 Examination : MID – I Examination Branch: Electrical Semester: Sub Code:3360901 Sub: SGP Date: 28/01/2019 Time: 10:30 Am – 11:30 Am Marks: : 20 Note: Attempt Any Four Question 1 Explain the following terms: (ANY TWO)

1. Breaking Capacity 2. Rate of rise of recovery of voltage 3. Restriking Voltage 05

2 Compare Isolator & Circuit Breaker . 05 3 Explain reactance earthing 05 4 State the desirable characteristics of protection system. 05 5 Explain Importance and advantages of neutral earthing. 05

6 Give difference between instrument transformer and protection transformer 05 નૉધ: કોઈ પણ ચાર નો લખો.

૧ નીચેના પદો સમ વો. (કોઈપણ બ)ે

૧. ે કગ કપેસીટ ૨. રટ ઓફ રાઇજ ઓફ રકવર વો ટજ ૩. ર ા કગ વો ટજ

૦૫

૨ આઈસોલેટર અને સ કટ ેકર વચનેી લુના આપો. ૦૫

૩ ર અકડ ચ અરથ ગ સમ વો ૦૫

૪ ોટકશન સી ટમની ઇ છત લા ણકતાઓની જણાવો. ૦૫

૫ ુ લ અિથના મહ વો અને ફાઇદા સમ વો. ૦૫

૬ સી.ટ .અને પી.ટ . વ ચનેો તફાવત જણાવો ૦૫

1/3

Seat No.: ________ Enrolment No.______________

GUJARAT TECHNOLOGICAL UNIVERSITY DIPLOMA ENGINEERING – SEMESTER – VI • EXAMINATION –SUMR- 2018

Subject Code: 3360901 Date: 01-05 - 2018

Subject Name: SWITCHGEAR & PROTECTION

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.

4. Use of programmable & Communication aids are strictly prohibited.

5. Use of only simple calculator is permitted in Mathematics.

6. English version is authentic.

Q.1 Answer any seven out of ten. દશમ ાંથી કોઇપણ સ તન જવ બ આપો. 14

1. State difference between symmetrical and unsymmetrical faults.

૧. સસમેટ્રીકલ અને અનસસમેટ્રીકલ ફોલ્ટ વચ્ચેનો તફ વત લખો.

2. State the types of faults occurring in the overhead line .

૨. ઓવરહડે લ ઈનમ ાં થત સવસવધ ફોલ્ટન પ્રક ર લખો.

3. State methods of neutral earthing and draw anyone.

૩. ન્યટુ્રલ અથીગ કરવ ની રીતોન પ્રક ર લખી કોઈપણ એક દોરો.

4. Explain necessity of protective transformers.

૪. પ્રોટેક્ટીવ ટ્ર ાંસ્ફોમમરની જરૂરીય ત સમજાવો.

5. write specifications (name plate) of CT.

૫. સી.ટી ન સ્પેસીફીકેશન (નેમ પ્લેટ) લખો.

6. Define minimum fusing current and fusing factor related to fuse.

૬. ફયઝુન સ થે સાંકળ યેલ મીનીમમ ફયઝુીગ કરાંટ અન ે ફયઝુીગ ફેક્ટર સમજાવો.

7. List characteristics of HRC fuse.

૭. એચ.આર સી ફયઝુની કેરેટરીસ્ટીકસ લખો.

8. Which type tests are performed on circuit breaker?

૮. સકીટ બ્રેકર મ કય પ્રક ર ન ટ ઇપ ટેસ્ટ કરવ મ આવે છે?

9. Explain TSM and PSM.

૯. TSM અ ને PSM સમજાવો.

10. Draw block diagram of µP based inverse time over current relay.

૧૦. µP આધ રીત ઇનવસમ ટ ઇમ ઓવર કરાંટ રરલે ની ખાંડ આક્રુસત દોરો.

Q.2 (a) Give difference between current transformer and potential transformer. 03

પ્રશ્ન. ર (અ) કરાંટ ટ્ર ન્સ્ફોમમર અને પોટેંસશયલ ટ્ર ન્સ્ફોમમર વચ્ચે નો ભેદ સમજાવો. ૦૩

OR

(a) Compare isolator and circuit breaker. 03

(અ) સરકિટ બ્રેકર અને આઇસોલેટર ની સરખ મણી કરો. ૦૩

(b) Write advantages and disadvantages of HRC fuse. 03

(બ) એચ આર સી ફયઝુ ન ફ યદ અને ગેર ફ યદ લખો. ૦૩

OR

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(b) Explain restriking voltage wrt circuit breaker. 03

(બ) સરકિટ બે્રકર ન સાંદભમ મ ાં રરસ્ટ્ર ઇકીંગ વોલ્ટેજ સમજાવો. ૦૩

(c) Explain high resistance interruption of arc in circuit breaker. 04

(ક) સરકિટ બ્રેકર મ ાં આકમ નુાં ઉચ્ચ પ્રસતરોધ ઇંટરપ્શન સમજાવો. ૦૪

OR

(c) Explain low resistance interruption of arc in circuit breaker. 04

(ક) સરકિટ બ્રેકર મ ાં આકમ નુાં લો પ્રસતરોધ ઇંટરપ્શન સમજાવો ૦૪

(d) Explain working of SF6 circuit breaker with diagram. 04

(ડ) SF6 સરકિટ બ્રેકર ની ક યમ પધ્ધ્્ત આક્રુસત સરહત સમજાવો. ૦૪

OR

(d) Explain working of vacuum circuit breaker with diagram. 04

(ડ) વેક્યમુ સરકિટ બ્રેકર ની ક યમ પધ્ધ્્ત આક્રુસત સરહત સમજાવો. ૦૪

Q.3 (a) Explain working of shaded pole type induction disc relay with diagram. 03

પ્રશ્ન. 3 (અ) શેડેડ પોલ પ્રક ર ન ઇંડક્શન રડસ્ક રરલે ની ક યમ પધ્ધ્્ત આક્રુસત સરહત સમજાવો.

૦૩

OR

(a) Write short note on Buchholz relay. 03

(અ) બકુોલ્ઝ રરલે પર ટુાંક નોંધ લખો. ૦૩

(b) Describe the directional feature of directional over current relay. 03

(બ) ડ યરેક્શનલ ઓવર કરાંટ રરલે ની ડ યરેક્શનલ લ ક્ષણણક્ત વણમવો. ૦૩

OR

(b) Explain construction and working of thermal relay with diagram. 03

(બ) થમમલ રરલે ની ક યમ પધ્ધ્્ત આક્રુસત સરહત સમજાવો. ૦૩

(c) Explain working of negative phase sequence relay. 04

(ક) નેગેટીવ ફેઝ સસક્વાંસ રરલે ની ક યમ પધ્ધ્્ત આક્રુસત સરહત સમજાવો. ૦૪ OR

(c) Draw block diagram of static over current relay and explain each block. 04

(ક) સ્ટેરટક ઓવર કરાંટ રરલે ની ખાંડ આક્રુસત દોરો અને દરેક ખાંડ સમજાવો. ૦૪

(d) Explain protection of ring mains. 04

(ડ) રરિંગ મેઇન ન ુસાંરક્ષણ સમજાવો. ૦૪

OR

(d) Explain voltage balance type protection for transmission line. 04

(ડ) ટ્ર ાંધ્ધન્સ્મશન લ ઇન મ ટે વોલ્ટેજ બેલેંસ પ્રક ર નુાં સ ાંરક્ષણ સમજાવો. ૦૪

Q.4 (a) Compare unit and non unit systems for line protection. 03

પ્રશ્ન. ૪ (અ) લ ઇન સાંરક્ષણ મ ટે યસુનટ અને નોન યસુનટ સસસ્ટમ ની સરખ મણી કરો. ૦૩

OR

(a) Explain circulating current protection for transmission line. 03

(અ) ટ્ર ાંધ્ધન્સ્મશન લ ઇન મ ટે સક્યુમલેટીંગ કરાંટ પ્રક ર નુાં સ ાંરક્ષણ સમજાવો ૦૩

(b) Explain carrier current protection with diagram. 04

(બ) કેરરયર કરાંટ સાંરક્ષણ આક્રુસત સરહત સમજાવો. ૦૪

OR

(b) State and explain abnormalities and faults in motor. 04

(બ) મોટરમ ાં ઉદભવતી એબ્નોમમણલટી અને ખ સમઓ લખો અને સમજાવો. ૦૪

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(c) List types of distance relay and explain anyone in detail. 07

(ક) રડસ્ટન્સ રરલે ન પ્રક ર લખો અને કોઇ પણ એક સમજાવો. ૦૭

Q.5 (a) What is percentage differential protection? Draw percentage differential

system for Δ-Y transformer. 04

પ્રશ્ન. ૫ (અ) પરસાંટેજ ડીફ્રાંસશયલ સાંરક્ષણ શુાં છે? ડેલ્ટ સ્ટ ર ટ્ર ાંસ્ફોમમર મ ટે એ દોરો. ૦૪

(b) Explain restricted earth fault protection for transformer. 04

(બ) ટ્ર ાંસ્ફોમમર મ ટે રરસ્ટ્સ્ટ્રક્ટેડ અથમ ફોલ્ટ સાંરક્ષણ સમજાવો. ૦૪

(c) Write short note on surge absorber. 03

(ક) સર્જ એબ્સોબમર પર ટુાંક નોંધ લખો. ૦૩

(d) Explain working of horn gap arrester. 03

(ડ) હોનમ ગેપ એરેસ્ટર નુાં ક યમ સમજાવો. ૦૩

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GUJARAT TECHNOLOGICAL UNIVERSITY DIPLOMA ENGINEERING – SEMESTER – VI EXAMINATION –WINTER - 2018

Subject Code:3360901 Date: 29-11-2018

Subject Name:Switchgear & Protection

Time:02:30 PM TO 05:00 PM Total Marks: 70 Instructions:








1. Draw block diagram of basic arrangement of protective system.

૧. પ્રોટેક્ટટવ ક્સસ્ટમની મૂળભૂત ગોઠવણીનો બ્લોક ડ ય ગ્ર મ દોરો.

2. State the precautions to be taken while operating CT.

૨. કરાંટ ટ્ર ન્સફોમમરને ઓપરેટ કરતી વખતે ધ્ય નમ ાં લેવી પડતી ચેતવણીઓ જણ વો.

3. State necessity of back protection and write types of back protection.

૩. બેકઅપ પ્રોટેટશનની જરૂરરય ત જણ વો અને તેન પ્રક રો લખો.

4. Explain use of earth switch.

૪. અથમ ક્સ્વચની ઉપયોક્ગત સમજાવો.

5. Draw block diagram of microprocessor based inverse time over current relay.

૫. મ ઇક્રો પ્રોસેસર બેઝ ઇન્વસમ ટ ઇમ ઓવર કરાંટ રીલેનો બ્લોક ડ ય ગ્ર મ દોરો.

6. State the routine test performed on circuit breaker.

૬. સરરકટ બ્રેકર પર કરવ મ ાં આવત રુરટન ટેસ્ટ જણ વો.

7. State the main functions of auxiliary relay.

૭. ઓક્ટઝલરી રીલેન ાં મ ખ્ય ક યમ જણ વો.

8. State abnormalities that can occur in alternator.

૮. ઓલ્ટરનેટરમ ાં ઉદ્દભવતી ખ મીઓ જણ વો.

9. Explain function of ground wire for protection against lightning stroke.

૯. આક શી વીજળીથી રક્ષણ મેળવવ મ ટે ગ્ર ઉન્ડ વ યરન ાં ક યમ સમજાવો.

10. State causes of over voltage in power system.

૧૦. પ વર ક્સસ્ટમમ ાં ઓવર વોલ્ટેજ થવ ન ક રણો જણ વો.

Q.2 (a) Explain high resistance interruption method of quenching arc in circuit

breaker.

03

પ્રશ્ન. ર (અ) સરરકટ બ્રેકરમ ાં આકમને ઓલવવ ની હ ઇ રેક્ઝસ્ટન્સ ઇન્ટપ્સન રીત સમજાવો. ૦૩

OR

(a) Explain terms. (i) Recovery voltage (ii) RRRV 03

(અ) પદ સમજાવો. . (i) રરકવરી વોલ્ટેજ (ii) RRRV ૦૩

(b) In a relay plug setting is 150% and CT ratio is 500/5. If the fault current is

4350 Amp, find (i) Fault current of relay (ii) PSM (iii) Pick up current

03

(બ) એક રીલેમ ાં પ્લગ સેટટાંગ 150% છે અને સીટી રેક્શઓ 500/5 છે. જો ફોલ્ટ કરાંટ 4350 એક્પપયર ૦૩

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હોય તો (i) રીલેનો ફોલ્ટ કરાંટ (ii) PSM (iii) ક્પક અપ કરાંટ શોધો.

OR

(b) What is meant by IDMT relay? Draw characteristics of such relay and state its

applications.

03

(બ) IDMT રીલ ેએટલ ેશ ાં તે સમજાવો. આ પ્રક રન રીલેની લ ક્ષક્ણકત ઓ દોરો અને તેની

ઉપયોક્ગત ઓ જણ વો.

૦૩

(c) Explain working of SF6 circuit breaker. 04

(ક) SF6 સરરકટ બે્રકરન ાં ક યમ સમજાવો. ૦૪

OR

(c) Explain working of cross blast air break circuit breaker. 04

(ક) ક્રોસ બ્લ સ્ટ એર બ્રેક સરરકટબે્રકરન ાં ક યમ સમજાવો. ૦૪

(d) Give difference between instrument transformer and protective transformer. 04

(ડ) ઇન્સ્ુમેન્ટ ટ્ર ન્સફોમમર અને પ્રોટેક્ટટવ ટ્ર ન્સફોમમર વચ્ચેનો તફ વત જણ વો. ૦૪

OR

(d) Explain working of Peterson coil earthing with diagram, 04

(ડ) ડ ય ગ્ર મની મદદથી ક્પટસમન કોઇલ અર્થિંગન ાં ક યમ સમજાવો. ૦૪

Q.3 (a) Explain frame leakage protection for protection of busbar. 03

પ્રશ્ન. 3 (અ) બસબ રન પ્રોટેટશન મ ટે ફે્રમ ક્લકેજ પ્રોટેટશન સમજાવો. ૦૩

OR

(a) Explain how thermal relay provide protection against single phasing in three

phase induction motor.

03

(અ) થ્રી ફેજ ઇન્ડટશન મોટરમ ાં થમમલ રીલ ેસસાંગલ ફેસજાંગ સ મે કેવી રીતે પ્રોટેટશન આપ ેછે તે સમજાવો. ૦૩

(b) Explain insulation coordination. 03

(બ) ઇન્સ્ય લેશન કો ઓર્ડમનેશન સમજાવો. ૦૩

OR

(b) Write short note on- Ferranti surge absorber. 03

(બ) ફેર ન્ટી સજમ એબસોબમર ક્વશ ેટૂાંક નોંધ લખો. ૦૩

(c) Discuss voltage balance system for protection of transmission line with its

merits and demerits.

merits and demerits.

04

(ક) ટ્ર ન્સક્મશન લ ઇન ન પ્રોટેટશન મ ટે વોલ્ટેજ બેલેન્સ ક્સસ્ટમ ચચો. તેન ફ યદ ઓ અને

ગેરફ યદ ઓ જણ વો.

૦૪

OR

(c) Explain direction time graded protection for parallel feeders. 04

(ક) પેરેલલ ફીડર મ ટે ડ યરેટશન ટ ઇમ ગ્રેડેડ પ્રોટેટશન સમજાવો. ૦૪

(d) Explain construction and working of Buchholz relay. 04

(ડ) બ કોલ્ઝ રીલેની રચન અને ક યમ સમજાવો. ૦૪

OR

(d) Explain construction and working of negative phase sequence relay. 04

(ડ) નેગેટીવ ફેજ સીટવન્સ રીલેની રચન અને ક યમ સમજાવો. ૦૪

Q.4 (a) Give comparison between unit and non unit systems for line protection. 03

પ્રશ્ન. ૪ (અ) લ ઇનન પ્રોટેટશન મ ટે ય ક્નટ અને નોન ય ક્નટ ક્સસ્ટમની સરખ મણી કરો. ૦૩

OR

(a) Explain non directional time graded over current protection system for

protection of line/feeder.

03

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(અ) લ ઇન/ફીડરન પ્રોટેટશન મ ટેની નોન ડ યરેટશનલ ટ ઇમ ગ્રેડેડ ઓવર કરાંટ પ્રોટેટશન ક્સસ્ટમ

સમજાવો.

૦૩

(b) Explain Merz price protection system for protection of star delta connected

power transformer.

04

(બ) સ્ટ ર ડેલ્ટ ટ્ર ન્સફોમમરન પ્રોટેટશન મ ટે મઝમ પ્ર ઇસ પ્રોટેટશનની રીત સમજાવો. ૦૪

OR

(b) Explain restricted earth fault protection for alternator. 04

(બ) ઓલ્ટરનેટર મ ટે રેક્સ્ટ્રટટેડ અથમ ફોલ્ટ પ્રોટેટશન સમજાવો. ૦૪

(c) Explain construction and working of mho type distance relay. Draw and

explain its characteristics on R-X diagram.

07

(ક) પહો ટ ઇપ રડસ્ટન્સ રીલેની રચન અને ક યમ સમજાવો. R-X ડ ય ગ્ર મ પર તેની લ ક્ષક્ણકત ઓ

દોરો અને સમજાવો.

૦૭

Q.5 (a) Describe construction and working of HRC fuse. 04

પ્રશ્ન. ૫ (અ) HRC ફ્ય જની રચન અને ક યમ વણમવો. ૦૪

(b) With the help of block diagram explain carrier current protection system for

protection of transmission line.

04

(બ) ટ્ર ન્સક્મશન લ ઇનન પ્રોટેટશન મ ટે બ્લોક ડ ય ગ્ર મની મદદથી કેરરયર કરાંત પ્રોટેટશન ક્સસ્ટમ

સમજાવો.

૦૪

(c) Explain negative phase sequence protection against unbalance load for

alternator.

03

(ક) ઓલ્ટરનેટરન અનબેલેન્સ લોડ મ ટે નેગેરટવ ફેજ ક્સટવન્સ પ્રોટેટશન સમજાવો. ૦૩

(d) Explain core balance type earth fault protection. 03

(ડ) કોર બેલેન્સ ટ ઇપ અથમ ફોલ્ટ પ્રોટેટશન સમજાવો. ૦૩

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GUJARAT TECHNOLOGICAL UNIVERSITY DIPLOMA ENGINEERING – SEMESTER –VI • EXAMINATION – SUMMER 2017

Subject Code: 3360901 Date:04-05-2017

Subject Name: Switch Gear and Protection.

Time: 10:30 AM TO 01:00 PM Total Marks: 70 Instructions:








1. List the various causes of fault.

૧. ફોલ્ટ થવ ન વવવવધ ક રણો જણ વો.

2. Define terms sensitivity and selectivity referred to protective relay.

૨. પ્રોટેક્ટીવ રીલે મ ટે સેન્સીટીવીટી અને સીલેક્ટીવીટી વણણવો.

3. Define plug setting multiplier and error for protective relay.

૩. પ્રોટેક્ટીવ રીલે મ ટે પ્લગ સેટીંગ મલ્ટીપ્લ યર અને એરર વણણવો.

4. Give classification of relay based upon their working principle.

૪. વકીંગ વપ્રન્સીપલન આધ રે રીલેન ાં વગીકરણ કરો.

5. What is the use of Protective transformer in protective system?

૫. પ્રોટેક્ટીવ સીસ્ટમમ ાં પ્રોટેક્ટીવ ટ્ર ન્સફોમણરન ાં ક યણ શ ાં છે?

6. What are the different methods of neutral earthing?

૬. ન્ય ટ્રલ અથીંગની વવવવધ રીતો જણ વો.

7. Define recovery voltage for circuit breaker.

૭. સકીટ બે્રકર મ ટે રીકવરી વોલ્ટેજ વણણવો.

8. List various circuit interrupting device along with their symbols.

૮. સકીટ ઇન્ટરપટીંગ ડીવ ઇસની ય દી તેની સાંજ્ઞ સ થે જણ વો.

9. Define voltage surge.

૯. વોલ્ટેજ સર્જ વણણવો.

10. List various types of surge arrestors.

૧૦. વવવવધ પ્રક રન સર્જ એરેસ્ટરની ય દી જણ વો.

Q.2 (a) Explain the necessity of backup protection and give its type. 03

પ્રશ્ન. ર (અ) બેક અપ પ્રોટેક્શનની જરૂરીય ત સમજાવો અને તેન પ્રક ર જણ વો. ૦૩

OR

(a) Define fault. Give difference between faults and abnormal condition. 03

(અ) ખોટક (ફોલ્ટ) ની વ્ય ખ્ય આપો. ફોલ્ટ અને અસ મ ન્ય પિર્સ્થવત વચ્ચેનો તફ વત સ્પષ્ટ કરો.

૦૩

(b) Explain the working of Balanced beam relay with neat diagram. 03

(બ) બેલેન્સ્ડ બીમ પ્રક રન રીલેન ાં ક યણ આક્રુવત સિિત સમજાવો. ૦૩

2/3

OR

(b) Draw the general arrangement of microprocessor based relay and explain its

working.

03

(બ) મ ઇક્રોપ્રોસેસર બેઇઝ્ડ રીલેની જનરલ વ્યવસ્થ દોરો અને ક યણ સમજાવો. ૦૩

(c) What are the limitation of static relay? 04

(ક) સ્ટેટીક રીલેની મય ણદીત જણ વો. ૦૪

OR

(c) Differentiate differential over current relay and directional power relay, 04

(ક) ડીફ્ર્નસીયલ ઓવર કરાંટ રીલે અને ડ યરેક્શનલ પ વર રીલેનો તફ વત આપો.

૦૪

(d) Give the classification of protection of line. 04

(ડ) લ ઇન પ્રોટેક્શનન ાં વગીકરણ આપો. ૦૪

OR

(d) Explain the protection of Ring main system. 04

(ડ) રીંગ મેઇન સીસ્ટમન ાં પ્રોટેક્શન સમજાવો. ૦૪

Q.3 (a) Write the advantages of neutral grounding. 03

પ્રશ્ન. 3 (અ) ન્ય ટ્રલ ગ્ર ઉન્ડીંગન ફ યદ જણ વો. ૦૩

OR

(a) Explain reactance earthing with diagram. 03

(અ) રીએક્ટન્સ અથીંગ આક્રુવત દોરી સમજાવો. ૦૩

(b) Explain working of HRC fuse . 03

(બ) HRC ફય ઝન ાં ક યણ સમજાવો. ૦૩

OR

(b) List different types of Isolators and explain any one with diagram. 03

(બ) વવવવધ પ્રક રન આઇસોલેટરની ય દી આપો અને કોઇપણ એક સમજાવો. ૦૩

(c) Explain following terms related to circuit breaker(a)Restriking voltage

(b) Rate of rise of restriking voltage

04

(ક) સકીટ બે્રકરન સાંદર્ણમ ાં (એ) રીસ્ટ્ર ઇકીંગ વોલ્ટેજ, (બી) રેટ ઓફ ર ઇઝ ઓફ રીસ્ટ્ર ઇકીંગ વોલ્ટેજ સમજાવો.

૦૪

OR

(c) Explain low resistance arc interruption method in circuit breaker. 04

(ક) સકીટ બ્રેકરમ ાં લો રેઝીસ્ટન્સ આકણ ઇન્ટ્રપ્શન પધ્ધવત સમજાવો. ૦૪

(d) Describe the construction of SF6 circuit breaker. 04

(ડ) SF6 સકીટ બ્રેકરની ક યણરચન સમજાવો. ૦૪

OR

(d) Give classification of oil circuit breaker. 04

(ડ) ઓઇલ સકીટ બે્રકરન ાં વગીકરણ આપો. ૦૪

Q.4 (a) Explain differential protection for alternator with diagram. 03

પ્રશ્ન. ૪ (અ) ઓલ્ટરનેટર મ ટેન ાં ડીફ્ર્નસીયલ પ્રોટેક્શન આક્રુવત દોરી સમજાવો. ૦૩

OR

(a) Draw and explain Time graded scheme for feeder protection. 03

(અ) ફીડર પ્રોટેક્શન મ ટેની ટ ઇમ ગે્રડેડ સ્કીમ આક્રુવત દોરી સમજાવો. ૦૩

(b) Explain frame leakage protection for Bus-bar. 04

3/3

(બ) બસબ ર ફે્રમ લીકેજ પ્રોટેક્શન સમજાવો. ૦૪

OR

(b) Explain circulating current protection for Bus-bar. 04

(બ) બસબ રન ાં સરક્ય લેટીંગ કરાંટ પ્રોટેક્શન સમજાવો. ૦૪

(c) Explain biased differential protection for three phase transformer with

diagram.

07

(ક) ત્રણ-પ્ર વસ્થ ટ્ર ન્સફોમણર મ ટે બ યસ્ડ ડીફરન્શીયલ પ્રોટેક્શન આક્રુવત સ થે સમજાવો.

૦૭

Q.5 (a) What is over voltage and Explain working of surge arrestor. 04

પ્રશ્ન. ૫ (અ) ઓવર વોલ્ટેજ એટલે શ ાં?, સર્જ એરેસ્ટરન ાં ક યણ સમજાવો. ૦૪

(b) Explain distance protection scheme for transmission line. 04

(બ) ટ્ર ન્સમીશન લ ઇન મ ટે ડીસ્ટન્સ પ્રોટેક્શન સમજાવો. ૦૪

(c) Give difference between Instrument transformer and Protection transformer. 03

(ક) ઇન્ુમેન્ટ ટ્ર ન્સફોમણર અને પ્રોટેક્શન ટ્ર ન્સફોમણર વચ્ચેનો તફ વત આપો. ૦૩

(d) List various protection provided to Induction motor. 03

(ડ) ઇન્ડક્શન મોટરન વવવવધ પ્રોટેક્શનની ય દી આપો. ૦૩

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LAXMI INSTITUTE OF TECHNOLOGY, SARIGAM · 2019. 3. 4. · Explain setting of relays. 3f. Describe...

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