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Maintenance of Transformer and Circuit Breaker Course Code:3360907

GTU/ NITTTR Bhopal/14-15 Gujarat State

GUJARAT TECHNOLOGICAL UNIVERSITY, AHMEDABAD, GUJARAT

COURSE CURRICULUM

COURSE TITLE: MAINTENANCE OF TRANSFORMER AND CIRCUIT BREAKER

(COURSE CODE: 3360907)

Diploma Programme in which this course is offered Semester in which offered

Electrical Engineering Sixth

1. RATIONALE

Power system consists of a number of transformers, circuit breakers installed at substations

including poll mounted distribution transformers whose numbers are in thousands only in

Gujarat. These require regular maintenance to prevent permanent break down. Most of the

industries and big commercial installations such as big institutes/hotels/complexes/hospitals

that have their own substation also require maintenance of transformers and circuit breakers

on regular basis. Most of the big cities are now establishing their own Metro railways. Indian

Railways and city metros also have their own substations where transformer and circuit

breakers are installed. Power companies also off load their maintenance work of distribution

transformers and circuit breakers to private agencies. Thus there is huge demand for

maintenance of transformers and circuit breakers.

Transformer and Circuit Breakers are one of the two electric equipment who operate at

highest possible voltage i.e up to the level of 400 KV (generators and motors normally

operate up to 33 KV Class). Moreover in transformers and circuit breakers current breaking

and making takes place with full power (In transformer it happens in on load tap changer).

Because of these conditions of very high voltage operations and breaking and making of full

power current, insulating oil of transformers and circuit breakers is subjected to deterioration.

Contacts of the circuit breaker are also subjected to deterioration due to formation of arcs.

Because of these reasons these equipment require regular maintenance.

This course will enable the diploma pass out student to understand the concepts, principles

and acquire basic skills of testing and maintenance of transformers and circuit breakers. There

is a huge scope of self employment in this area with very less investment of capital.

2. COMPETENCY

The course content should be taught and implemented with the aim to develop required skills

in the students so that they are able to acquire following competency:

Maintain transformers and circuit breakers.

3. COURSE OUTCOMES

The theory should be taught and practical should be carried out in such a manner that students

are able to acquire different learning outcomes in cognitive, psychomotor and affective

domain to demonstrate following course outcomes.

i. Undertake /apply preventive maintenance

ii. Maintain power and distribution transformers.

iii. Commission different types of transformers

iv. Maintain different types of circuit breakers



4. TEACHING AND EXAMINATION SCHEME

Teaching Scheme

(In Hours)

Total

Credits

(L+T+P)

Examination Scheme1

Theory Marks Practical

Marks

Total

Marks

L T P C ESE PA ESE PA

150 3 0 2 5 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 CONTENT DETAILS

Unit Major Learning Outcomes

(in cognitive domain)

Topics and Sub-topics

Unit – I.

Preventive

Maintenance

1a. State the types of maintenance.

1b. Explain the significance of

Preventive maintenance.

1c. Describe the economy of

maintenance.

1.1 Maintenance and its types -

Preventive and Breakdown

1.2 Advantages of preventive

maintenance

1.3 Scope of preventive

maintenance

1.4 Economics of preventive

maintenance

Unit– II

Maintenance of

Transformers

2a. Describe maintenance of

different parts of power

transformer.

2b. Explain the different factors

affecting the life of transformer.

2c. Prepare maintenance schedule

of different types of

transformer.

2d. Explain the importance of

quality of transformer oil.

2e. Describe the transformer oil

filtration procedure

2f. List the parameters for quality

of oil.

2g. Describe Trouble shooting

procedure of power transformer.

2h. Inspect and maintain

distribution and power

transformer.

2i. Describe the causes of failure of

transformers

2j. Describe the methods to reduce

the noise level in transformer.

2k. Describe how from analyses of

2.1 Significance of transformer

maintenance

2.2 Parts of transformer- tank.

Core, winding, conservator,

radiators, bushings, terminals,

temperature measurement

system, safety valves, tap

changers and accessories/

fittings etc.

2.3 Factors affecting the life of

transformer-moisture, water

oxygen, solid impurities,

varnish, slackness of windings

and dust.

2.4 Inspection-sensory, records and

electrical test.

2.5 General/Typical maintenance

schedule of power

transformers-up to 1000 kVA

and above 1000 kVA

2.6 Maintenance of transformer oil-

characteristic, interpretation of

tests, procedure of testing BDV,

filtering plant.






gas collected in Buchholz relay,

condition of transformer may be

ascertained.

2l. State procedure for measuring

of insulation resistance of

transformers.

2m. Sate safety precautions to be

absorbed during maintenance of

transformers.

2.7 Causes of failures of power

transformers and preventive

actions.

2.8 Detective devices-Buchholz

relay, Pressure relief device,

Differential relay, Dial

thermometer alarm contact,

Over current relay, ground fault

relay, voltmeter, ammeter,

Human senses

2.9 Check list of maintenance of

power transformers

2.10 Causes and methods to reduce

Audible Noise (AN) from

transformer

2.11 Maintenance of distribution

transformer

i. Reasons for failure of

Distribution Transformers

and the remedial measures

thereof

ii. Inspection & Maintenance

Schedule for Distribution

Transformers:

iii. Inspection & Maintenance of

transformer and accessories

within the sub-station and its

proximity.

2.12 Procedure of measuring the

insulation resistance of

transformer windings.

Unit– III

Commissioning

and

Recharging of

Transformers

3a. Understand the procedure of

commissioning of power

transformer.

3b. Perform required test after

commissioning of transformer.

3c. State do’s and don’ts for power

transformer.

3d. Describe the procedure of

loading the transformer.

3.1 Concept of commissioning and

recharging of transformer.

3.2 General checks

3.3 Insulation resistance test

3.4 Measurement of oil

characteristics

3.5 Off circuit tap switch

3.6 Continuity test

3.7 Measurement of winding

resistance

3.8 Voltage ratio tests

3.9 Magnetizing current

3.10 Charging of the transformer

3.11 Do’s and Don’ts for transformer

3.12 Various commissioning tests on

a power transformers






3.13 Procedure of loading the

transformers.

3.14 Transformer grounding.






Unit–IV

Maintenance of

Circuit Breaker

4a. Describe the importance of

maintenance of circuit breaker.

4b. Describe the procedure for the

maintenance of Moulded circuit

breaker.

4c. State the frequency of

maintenance and its procedure

for various Voltage rating of

circuit breaker.

4d. Describe the Maintenance of

Oil, Air, Air blast, SF6 and

Vacuum circuit breaker.

4e. State the causes of Failure of

circuit breaker

4f. Describe the trouble shooting

procedure of circuit breaker.

4g. Explain the operating

mechanism of circuit breaker.

4h. Describe the procedure for

filling SF6 in Circuit Breaker.

4i. State the characteristics of SF6

Gas which makes it useful for

CB.

4j. Describe factor effecting life of

arcing contacts of CB.

4k. List causes of failure of CB

4l. Describe operating mechanism

of HVAC Circuit Breaker.

4m. State safety precautions to

be observed during maintenance

of CBs.

4.1 Steps in maintenance of CB

4.2 Maintenance of moulded case

circuit breakers -Frequency and

routine maintenance tests

4.3 Maintenance of low-voltage

circuit breakers -Frequency and

maintenance procedures

4.4 Maintenance of medium-

voltage circuit breakers – Air,

Oil and Vacuum circuit

breakers - Frequency of

maintenance, safety practices

and maintenance procedures for

each of the above

4.5 Maintenance of high-voltage

circuit breakers - frequency of

inspections, External and

internal inspection guidelines,

typical internal breaker

problems, Influence of duty

imposed, Types of tests

performed.

4.6 OIL CB, Post fault

maintenance, Steps in

maintenance of MOCB

4.7 Maintenance for AIR CB and

Frequency of maintenance.

4.8 Maintenance of AIR BLAST

CB

4.9 Maintenance of SF6 gas circuit

breakers

i. Properties of SF6 (sulphur

hexafluoride) gas

ii. Handling non faulted SF6

iii. Handling faulted SF6

iv. Procedure of filling SF6 gas

in single pressure puffer type

SF6 CB

v. Gas monitoring system and

gas handling system for SF6

filled equipment

vi. Types and function of SF6

gas handling units.

vii. Maintenance of SF6 CB

4.10 Maintenance of VACCUM CB

4.11 Life of arcing contacts in

various CB in case of normal






current switching and short

circuit operation

4.12 Causes of failure of CB, trouble

shooting and procedure of

failure analysis.

4.13 Typical Record card for

maintenance work of CB

4.14 Commissioning tests on HV

A.C. CB

4.15 Operating mechanism used in

HV A.C. CB

4.16 Safety precautions to be taken

in maintenance of CB

6. SUGGESTED SPECIFICATION TABLE WITH HOURS AND MARKS (Theory)

Unit

No.

Unit Title Teaching

Hours

Distribution of Theory Marks

R

Level

U

Level

A

Level

Total

Marks

I I Preventive Maintenance 4 5 2 0 7

II I

I

Maintenance of Transformer 16 8 10 10 28

III I

I

I

Commissioning and Recharging of

Transformers

8

6

4

4 14

IV I

V

Maintenance of Circuit Breaker 14

6

7

8

21

Total 42 25 23 22 70

Legends: R = Remember U= Understand; A= Apply and above levels (Bloom’s revised 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 EXERCISES/PRACTICALS

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

develop different types of skills (outcomes in psychomotor and affective domain) so that

students are able to acquire the competencies/programme outcomes. 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 certain outcomes in affective domain which would in turn lead to development of Course

Outcomes related to affective domain. Thus over all development of Programme Outcomes

(as given in a common list at the beginning of curriculum document for this programme)

would be assured.

Faculty should refer to that common list and should ensure that students also acquire

outcomes in affective domain which are required for overall achievement of Programme

Outcomes/Course Outcomes.



S. No. Unit

No.

Practical Exercises

(outcomes in Psychomotor Domain)

Approx

Hours.

required

1 I Prepare a technical report on the preventive maintenance of

transformer which supplies electrical power to your college. 2

2 I Give comparison analysis between preventive and breakdown

maintenance. 2

3 II Prepare detail specifications data sheet for different

transformer.(refer name plate mounted on transformers)

2

4 II Prepare a technical report on various accessories and fitments on

a power transformer in a substation.

4

5 II Perform various tests applied to insulating oil. 4

6 II Prepare a technical report on various causes of troubles and

failures of power transformer.

4

7 II Prepare typical maintenance schedule for transformers up to

1000 KVA

4

8 II Prepare typical maintenance schedule for transformers above

1000 KVA

4

9 II Prepare a technical report on filtering process and filtering plant

for transformer oil filtration.

2

10 III Prepare test report of a power transformer after commissioning. 4

11 III Read and interpret I.E. rules pertaining to testing of

transformer.

4

12 III Perform insulation resistance test of transformer. 2

13 III Perform voltage ratio tests of three phase transformer. 2

14 III Read and interpret I.E. rules pertaining to commissioning of

transformer.

4

15 IV Prepare detail specifications data sheet for different circuit

breaker.(use name plate)

2

16 IV Prepare a technical report on various types of tests performed on

high voltage ac circuit breakers.

4

17 IV Prepare a technical report on maintenance of air blast circuit

breaker.

4

18 IV Prepare a technical report on maintenance of SF6 circuit breaker. 2

19 IV Prepare a technical report on maintenance of Vacuum circuit

breaker.

2

20 IV Prepare test report of tests on HVA.C. Circuit Breaker after

commissioning.

2

Total Hours 62

Note: Perform any of the practical exercises for a minimum of 28 hours from above list depending

upon the availability of resources so that skills related with the most of the outcomes in all the

units are developed.

8. SUGGESTED STUDENT ACTIVITIES

Following is the list of proposed student activities such as:

i. Prepare journals based on practical performed in laboratory.

ii. Prepare chart displaying various parts of transformer of different types etc.

iii. List the names, specifications and make of the mountings/accessories used on nearby

power transformer.

iv. Prepare a report on various types of oil conservation systems and cooling systems

used in power transformers.



v. Survey the market for different type of transformer and circuit breaker oil available

and compare their specifications with respect to effect of those parameters on life and

functioning of equipment.

vi. Prepare chart displaying various parts of circuit breaker of different types etc.

vii. Visit nearby substation, transformer manufacturing & testing laboratories.

viii. Visit maintenance site / workshop of transformer and circuit breaker.

9. SPECIAL INSTRUCTIONAL STRATEGIES (if any)

(a) Show video/animation film to demonstrate maintenance procedures for

transformer/circuit breakers.

(b) Arrange a visit to nearby industry/substation to observe

maintenance/installation/commissioning of transformer and circuit breakers.

(c) Arrange expert lectures of the professional engineers involved in maintenance,

installation, commissioning and testing of transformers and circuit breakers.

(d) Give Mini projects to students

10. SUGGESTED LEARNING RESOURCES

A) Books

S.

No. Title of Book Author Publication

1.

Thesis on Self learning

package on maintenance of

33 KV class transformers

for diploma course in

electrical engineering.

Chouhan R.P.

Gupta S.K.

TTTI Western Region,

Bhopal.

(NITTTR)

2.

Testing Commissioning

operation and maintenance

of Electrical Equipments.

Rao S Khanna Publication (latest

edition)

3. Transformers BHEL TATA McGraw-Hill

4.

Relavent IS Code for--

Maintenance of

Transformer, circuit

breaker ,switchgears,

insulating oil

- Latest code

B) Major Equipment/ Instrument with Broad Specifications

1. Oil testing kit. Mains Supply : 230V AC ±10%, 50Hz

Single Phase Variac : 230V/ 0-270V

High Voltage Source : 80kV, 20mA

Voltmeter : 0 to 100kV

2. Megger. Insulation Testing:250V:500V:1000V:

1000 MΩ range, Auto-ranging, Auto discharge

3. Model of transformer. Wooden, Plastic, etc material.

4. Voltage ratio test kit. For small 3 phase transformer

5. Model of circuit breaker. Wooden, Plastic, etc material.



C) List of Software/Learning Websites

i. www.nptel.iitm.ac.in

ii. www.youtube

iii. www.howstuffworks.com

iv. http://electrical-engineering-portal.com/

11. COURSE CURRICULUM DEVELOPMENT COMMITTEE

Faculty Members from Polytechnics

Prof. H. C. Chawda, Lecturer in Electrical Engineering, RC Technical Institute,

Ahmedabad

Prof. C. T. Patel, Lecturer in Electrical Engineering, RC Technical Institute,

Ahmedabad.

Coordinator and Faculty Members from NITTTR Bhopal

Prof. (Mrs.) C S Rajeshwari, Professor and Head Electrical and Electronics

Engineering

Prof. Joshua Earnest, Professor, Department of Electrical and Electronics

Engineering

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

http://www.youtube/

http://www.howstuffworks.com/

http://electrical-engineering-portal.com/

Academic

Laxmi Institute of Technology, Sarigam Diploma Electrical Engineering Department

Year: 2018-19 ASSIGNMENT: 1

Name of Subject : Maintenance of transformer and circuit breaker Date:

Subject Code : 3360907

Unit: 1

Sr. No. Name of Question Remarks

1. What are the different types of maintenance?

2. Explain significance of preventive maintenance.

3. Classify the preventive maintenance & explain any one of them.

4. What is overhauling of the Electrical machines?

5. Write the advantages of preventive maintenance.

6. Write any five functions of preventive maintenance department.

7. Write short note on break down maintenance.

8. What are the factors to be considered while preparing maintenance schedule?

9. What is the scope of the preventive maintenance .

10. Explain economics of preventive maintenance.

Date of Submission:-

Name & Sign of Subject In-charge :

Academic





Unit: 2


1. Explain the significance of maintenance of a power transformer

2. What is function of conservator , Breather and pressure relief valve?

3. Explain the working of Buchholz relay with neat sketch.

4. How the regeneration of Silica Gel of breather of transformer is done?

5. Distinguish between off circuit tap switch and on load tap changer.

6. Explain the factors which affecting the life of transformer.

7. Write annual maintenance schedule of transformer having capacity up to 1000 kVA.

8. Give daily inspection check points for power transformer rated above 1000 KVA.

9. Write the limiting value of B.D.V. , flash point and acidity for transformer oil.

10. Write various tests to be performed on transformer oil. Explain any one of them.

11. Explain the test procedure of breakdown voltage of transformer oil.

12. Explain any one method of filtration of transformer oil.

13. What are the cause of trouble and failure of power transformer cores?

14. What are the various causes of failure of power transformer. Explain any one with remedy of it.

Academic


Year: 2018-19 15.

Write and explain the causes of audible noise generation from transformer.

16. What are the different techniques for noise reduction in the transformer?

17. Which are the accessories used in distribution transformer?

18. Write reason for failure of distribution transformer and remedial measures for them.

19. Explain Insulation resistance test on a power transformer.

20. Why megger reading after 60 seconds is higher than initial megger reading?



Academic





Unit: 3


1. Explain the general check points after installation of power transformer.

2. Write the names of type tests performed on transformer.

3. Write test records related to insulation resistance measurement test of three phase transformer.

4. Explain the voltage ratio test for a transformer.

5. Which factors are affecting the insulation resistance of the transformer?

6. Describe the various steps for checking on load tap changer. Also distinguish between off circuit tap switch and on load tap changer.

7. Describe continuity test for transformer.

8. Explain the magnetizing current test for a transformer.

9. Which are the methods used to measure resistance of winding? Explain any one method of measurement of winding resistance of the power transformer.

10. Write any four important check points before charging power transformer.

11. List only the name of commissioning tests to be performed on a power transformer.

12. What is polarization index?

13. Write advantages of neutral grounding of transformer.



Academic


Year: 2018-19 Name of Subject : Maintenance of transformer and circuit breaker Date:


Unit: 4


1. Write down the routine test to be performed on MCCB. Explain any one routine test .

2. Explain the general maintenance procedure of low voltage circuit breaker .

3. Explain the maintenance procedure for medium voltage oil circuit breaker.

4. Explain the effect of normal duty on performance of high voltage circuit breaker.

5. Write the steps for external inspection of high voltage circuit breaker

6. What are the different tests to be performed on High voltage AC circuit breaker?

7. What are the commissioning test on a HVAC circuit breaker.

8. Write and explain the properties of SF6 gas.

9. Explain the procedure of filling SF6 gas in single pressure puffer type SF6 C.B.

10. How the maintenance of Vaccum Interrupter is done in the VaccumCircuit breaker?

11. Explain the causes of failure of circuit breaker.

12. What is the safety precaution to be taken during maintenance of circuit breaker?



MAINTENANCE OF TRANSFORMER AND CIRCUIT BREAKER (3360907) Department of Electrical Engineering

Laxmi Institute of Technology, Sarigam(Diploma)

QUESTION BANK

Chapter 1 – Preventive Maintenance

1. What are the different types of maintenance? OR State different types of maintenance.

2. Explain significance of preventive maintenance. 3. What is meant by preventive maintenance? 4. Classify the preventive maintenance & explain any one of them. OR

State and explain activities performed during preventive maintenance. 5. What is overhauling of the Electrical machines? 6. Write the advantages of preventive maintenance. 7. Write any five functions of preventive maintenance department. 8. Which activities performed during breakdown maintenance? OR

Write short note on break down maintenance. 9. What are the factors to be considered while preparing maintenance schedule? 10. Explain predictive maintenance. State its advantages and disadvantages.

Chapter 2 – Maintenance of Transformers

1. What is significance of maintenance of power transformer? OR Explain the significance of maintenance of power transformer.

2. Explain functions of breather and conservator in transformer. 3. Explain the maintenance procedure of breather. 4. What is function of Buchholz relay and Breather? 5. Write functions of Buchholz relay in transformer. 6. Explain the maintenance procedure of Buchholz relay. 7. How the regeneration of Silica Gel of breather of transformer is done? 8. State the types of bushing used for different voltages. 9. Distinguish between off circuit tap switch and on load tap changer. 10. What is the function of pressure relief valve in transformer? 11. What are the probable reasons for slackness of transformer winding? 12. Explain the factors which affecting the life of transformer. OR

Explain the factors affecting the life of transformer. 13. Write the effect of oxygen on life of transformer. 14. Write annual maintenance schedule of transformer having capacity up to 1000 kVA. OR

Explain the maintenance schedule for upto 1000 KVA transformer. 15. Give daily inspection check points for power transformer rated above 1000 KVA. OR

Explain daily maintenance schedule for transformer above 1000kVA ratings. 16. What are the check points during inspection of surge diverter and relay? 17. Write permissible oil temperature and hot spot temperature of winding for power transformer. 18. State the causes of deterioration of transformer oil. 19. Write the limiting value of B.D.V. , flash point and acidity for transformer oil. 20. Write the abbreviations of (i) BDV (ii) PI (iii) CTC (iv) OLTC 21. Explain crackle test for transformer oil. 22. Write various tests to be performed on on transformer oil. Explain any one of them. OR

Write the name of tests which are generally performed on insulating oil. 23. Explain the test procedure of breakdown voltage of transformer oil. OR

Explain the procedure of testing of breakdown voltage of transformer oil. 24. Explain any one method of filtration of transformer oil. 25. Draw the diagram of centrifugal purifier for transformer oil. 26. What are the cause of trouble and failure of power transformer cores? 27. What are the various causes of failure of power transformer. Explain any one with remedy of it.

28. Give causes of low value of insulation resistance of electrical equipment. 29. Write reasons of failure of core in transformer. OR

Write any two reasons for failure of transformer core. OR State reasons for failure of core of the power transformer. OR Explain various causes of troubles and failures of cores. OR State four types of troubles that can arise in the core of power transformer.

30. Explain unscheduled maintenance of transformer. 31. Write causes of audible noise generation from transformer. OR

List parameters causing audible noise in transformer. OR What are the possible causes of audible noise in the transformer? OR Give different sources of noise generation in transformer, its effect and remedial measures to remove it.

32. Write methods for noise reduction in transformer. OR What are the different techniques for noise reduction in the transformer? OR Write the techniques used for reduction of noise in the transformer?

33. Write reason for failure of distribution transformer and remedial measures for them. 34. Which are the accessories used in distribution transformer? OR

List out accessories in large distribution transformer. 35. Explain any two reasons for failure of distribution transformer and its remedial measures. OR

What are the possible reasons for failure of distribution transformer? 36. Why megger reading after 60 seconds is higher than initial megger reading? OR

Why one minute megger reading always higher always the initial reading? 37. Explain Insulation resistance test on a power transformer. 38. Which factors are affecting the insulation resistance of the transformer?

Chapter 3 – Commissioning and Recharging of Transformers

1. What are the pre-commissioning checks of power transformer? 2. Give the possible check points during routine daily inspection of power transformer. 3. List the various commissioning test on the power transformer. OR

List only the name of commissioning tests to be performed on a power transformer. 4. Write the names of type tests performed on transformer. 5. Classify routine test, type test and special test on a transformer. 6. Write test records related to insulation resistance measurement test of three phase transformer. 7. Write effect of temperature on insulation resistance of transformer. 8. Describe continuity test for transformer. 9. Describe the various steps for checking on load tap changer. 10. Explain any one method to find out winding resistance of transformer. OR

Which are the methods used to measure resistance of winding? 11. Write any four important check points before charging power transformer. 12. Explain any one method of measurement of winding resistance of the power transformer. 13. Explain the voltage ratio test for a transformer. OR

Explain voltage ratio test for a transformer. 14. What is importance of magnetizing current test? OR

Explain the magnetizing current test for a transformer. OR Which information can be obtained by performing magnetizing current test on power transformer? OR For which conditions the magnetizing current is measured for transformer?

15. Explain the general check points after installation of power transformer. 16. What is polarization index? OR

Explain absorption co-efficient. 17. State any four points of preparation prior to commissioning of power transformer. 18. Explain the procedure for energizing of the power transformer. 19. State the permissible overload and its duration for ON type transformer 20. Write advantages of neutral grounding of transformer.

Chapter 4 – Maintenance of Circuit Breaker

1. What are the possible reasons for maintenance of circuit breaker? 2. Explain the general maintenance procedure of low voltage circuit breaker. 3. Explain any one routine test to be performed on MCCB. OR

List only the name of routine maintenance tests to be performed on the moulded case circuit breaker. OR Explain maintenance of moulded case circuit breaker.

4. Explain millivolt drop test related to contacts in circuit breaker. OR What is purpose of Milli-volt test on a circuit breaker? OR State the purpose of millivolt test on a circuit breaker.

5. State four possible causes of increase in the resistance of terminal poles of circuit breaker. 6. How the pressure between the contacts of circuit breaker is measured? OR

Explain maintenance steps for the following component of circuit breaker. OR (i) Contacts (ii) operating mechanism (iii) relay.

7. Give the name of components to be checked during maintenance of ABCB. 8. Explain maintenance procedure of air blast circuit breaker. 9. Explain the maintenance procedure of low voltage circuit breaker. 10. Explain the maintenance procedure of main arcing contacts in oil circuit breaker 11. State life of arcing contacts in air blast circuit breaker and vacuum circuit breaker in case of normal current

switching and short circuit operation. 12. Explain the maintenance procedure for medium voltage oil circuit breaker. 13. What are the information to be achieved during internal inspection of the circuit breaker 14. Write the steps for external inspection of high voltage circuit breaker. 15. What are the effects of heavy duty and light duty on the performance of high voltage circuit breaker? 16. Explain the effect of normal duty on performance of high voltage circuit breaker 17. Write two properties of SF6 gas. 18. Explain procedure of filling SF6 gas in SF6 circuit breaker. OR

Explain the procedure of filling SF6 gas in single pressure puffer type SF6 C.B. 19. Write maintenance procedure for interrupter of SF6 circuit breaker. 20. Explain SF6 gas monitoring system in SF6 circuit breaker.

How monitoring and handling of SF6 gas is carried out in SF6 circuit breaker? 21. What is the function of gas heaters in SF6 circuit breaker. 22. Explain maintenance procedure of vacuum circuit breaker. 23. Why life of contacts in vaccum circuit breaker is higher as compare to other circuit breakers? 24. How the maintenance of Vaccum Interrupter is done in the Vaccum Circuit breaker?

25. Write any four causes of failure of circuit breaker. OR Explain the causes of failure of circuit breaker. OR Write atleast two causes of failure of circuit breaker. OR What are the causes of failure of circuit breaker?

26. Prepare trouble shooting chart for the circuit breaker. 27. Prepare maintenance report card for circuit breaker. 28. Enlist various commissioning test performed on high voltage AC circuit breaker. OR

Explain the effect of normal duty on performance of high voltage circuit breaker. OR What are the different tests to be performed on High voltage AC circuit breaker? OR List out the different types of tests performed on high voltage a.c. breaker.

29. What is the safety precaution to be taken during maintenance of circuit breaker? OR Write safety precaution for maintenance of circuit breaker.

30. Explain method to check simultaneous contacts closing of three phase circuit breaker.

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

Academic Year 2018-19 Centre Code:691 Examination : Mid Exam I Semester: VI

Branch :Electrical Date:30.01.2019 Sub Code: 3360907

Sub : M.T.C.B. Time:10.30 AM to 11.30 AM Marks:20 Q-1 Answer any three. 6 1. What are the different types of maintenance? 2. What is overhauling of the Electrical machines? 3. How the regeneration of Silica Gel of breather of transformer is done? 4. Write functions of Buchholz relay in transformer. 5. What is the function of pressure relief valve in transformer? Q-2 (A) Write the advantages of preventive maintenance. 3 OR

(A) What are the factors to be considered while preparing maintenance schedule?

3

(B) Classify the preventive maintenance & explain any one of them. 3 OR

(B) Write short note on break down maintenance. 3 Q-3 (A) Explain the maintenance schedule for upto 1000 KVA transformer. 4 (B) Explain the factors which affecting the life of transformer. 4 OR

(A) What is significance of maintenance of power transformer? 4 (B) Distinguish between off circuit tap switch and on load tap changer. 4

-૧ કોઈપણ ણના જવાબ લખો ૬

૧. મેઇ ટન સ ના કારો જણાવો.

૨. ઈલેક લ મશીન ુઓવરહોલ ગ સમ વો.

૩. ા સફોમરના થરની દર રહલ સી લકા લને રએ ટવેટ કવી ર તે કર શકાય?

૪. ા સફોમરમાં કુોઝ ર લે ુકાય સમ વો .

૫. ા સફોમરમાં ેસર રલીફ વા વ ુકામ ુ ંછે?

-૨ (અ) િ વે ટવ મેઇ ટન સ ના ફાયદા જણાવો. ૩ અથવા

(અ) મેઇ ટન સ િશડ લુ તૈયાર કરતી વખતે કઇ બાબતો યાનમા ંરાખવી જોઈએ ? ૩

(બ) િ વે ટવ મેઇ ટન સ ુ વગ કરણ કર કોઇ એક મેઇ ટન સ િવશે સમ વો. ૩

અથવા

(બ) ેકડાઉન મેઇ ટન સ િવશે ૂંક ન ધ લખો. ૩

-૩ (અ) 1000 KVA મતા ધુીના ા સફોમર માટ ુમેઇ ટન સ િશડ લુ સમ વો. ૪

(બ) ા સફોમરની લાઇફ ઉપર અસર કરતા પા રબળો સમ વો ૪

અથવા

(અ) પાવર ા સફોમરના મેઇ ટન સ ુમહ વ સમ વો. ૪

(બ) ઓફલોડ ટપ વીચ અને ઓનલોડ ટપ ચે જર વ ચેનો તફાવત જણાવો. ૪

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

Academic Year 2018-19 Centre Code:691 Examination : Mid Exam I Semester: VI

Branch :Electrical Date:30.01.2019 Sub Code: 3360907

Sub : M.T.C.B. Time:10.30 AM to 11.30 AM Marks:20 Q-1 Answer any three. 6 1. What are the different types of maintenance? 2. What is overhauling of the Electrical machines? 3. How the regeneration of Silica Gel of breather of transformer is done? 4. Write functions of Buchholz relay in transformer. 5. What is the function of pressure relief valve in transformer? Q-2 (A) Write the advantages of preventive maintenance. 3 OR

(A) What are the factors to be considered while preparing maintenance schedule?

3

(B) Classify the preventive maintenance & explain any one of them. 3 OR

(B) Write short note on break down maintenance. 3 Q-3 (A) Explain the maintenance schedule for upto 1000 KVA transformer. 4 (B) Explain the factors which affecting the life of transformer. 4 OR

(A) What is significance of maintenance of power transformer? 4 (B) Distinguish between off circuit tap switch and on load tap changer. 4

-૧ કોઈપણ ણના જવાબ લખો ૬

૧. મેઇ ટન સ ના કારો જણાવો.

૨. ઈલેક લ મશીન ુઓવરહોલ ગ સમ વો.

૩. ા સફોમરના થરની દર રહલ સી લકા લને રએ ટવેટ કવી ર તે કર શકાય?

૪. ા સફોમરમાં કુોઝ ર લે ુકાય સમ વો .

૫. ા સફોમરમાં ેસર રલીફ વા વ ુકામ ુ ંછે?

-૨ (અ) િ વે ટવ મેઇ ટન સ ના ફાયદા જણાવો. ૩ અથવા

(અ) મેઇ ટન સ િશડ લુ તૈયાર કરતી વખતે કઇ બાબતો યાનમાં રાખવી જોઈએ ? ૩

(બ) િ વે ટવ મેઇ ટન સ ુ વગ કરણ કર કોઇ એક મેઇ ટન સ િવશે સમ વો. ૩

અથવા

(બ) ેકડાઉન મેઇ ટન સ િવશે ૂંક ન ધ લખો. ૩

-૩ (અ) 1000 KVA મતા ધુીના ા સફોમર માટ ુમેઇ ટન સ િશડ લુ સમ વો. ૪

(બ) ા સફોમરની લાઇફ ઉપર અસર કરતા પા રબળો સમ વો ૪

અથવા

(અ) પાવર ા સફોમરના મેઇ ટન સ ુમહ વ સમ વો. ૪

(બ) ઓફલોડ ટપ વીચ અને ઓનલોડ ટપ ચે જર વ ચેનો તફાવત જણાવો.. ૪

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Seat No.: ________ Enrolment No.______________

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

Subject Code: 3360907 Date: 06-05-2017

Subject Name: Maintenance of Transformer and Circuit Breaker

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. What is meant by preventive maintenance?

૧. પ્રિવેન્ટિવ મેઇનિેનટસ એિલે શ ાં?

2. State four types of troubles that can arise in the core of power transformer.

૨. પ વર ટ્ર ટસફોમમરન કોરમ ાં ઉદ્દભવતી ચ ર િક રની મ શ્કેલીઓ જણ વો.

3. State the causes of deterioration of transformer oil.

૩. ટ્ર ટસફોમમરન ાં ઓઇલ ખર બ થવ ન ક રણો જણ વો.

4. Write the name of tests which are generally performed on insulating oil.

૪. ઇટ્ય લેટિિંગ ઓઇલ પર સ મ ટય રીતે પરફોમમ કરવ મ ાં આવત િે્િન ન મ જણ વો.

5. State the types of bushing used for different voltages.

૫. જ દ જ દ વોલ્િેજ મ િે વપર ત બ પ્રશિંગન િક ર જણ વો.

6. For which conditions the magnetizing current is measured for transformer?

૬. ટ્ર ટસફોમમર મ િે મેગ્નેિ ઇઝ િંગ કરાંિ કઇ શરતો મ િે મપ ય છે?

7. State the permissible overload and its duration for ON type transformer.

૭. ઓન િ ઇપ ટ્ર ટસફોમમર મ િે પરપ્રમપ્રશબલ ઓવર લોડ અને તેનો સમય જણ વો.

8. State any four points of preparation prior to commissioning of power

transformer.

૮. પ વર ટ્ર ટસફોમમરને કપ્રમશપ્રનિંગમ ાં મકૂત ાં પહલે ાં તૈય રીન ચ ર મ દ્દ ઓ જણ વો.

9. State four possible causes of increase in the resistance of terminal poles of

circuit breaker.

૯. સરટકિ બ્રેકરન િપ્રમિનલ પોલન અવરોધમ ાં વધ ર ન ચ ર ક રણો જણ વો.

10. State life of arcing contacts in air blast circuit breaker and vacuum circuit

breaker in case of normal current switching and short circuit operation.

૧૦. નોમમલ કરાંિ સ્્વઝચિંગ અને શોિમ સરટકિ ઓપરેશન વખતે એર બ્લ ્િ સરટકિ બે્રકર અને વેક્ય મ સરટકિ બે્રકરમ ાં આટકિંગ કોટિેકિન ાં આય ષ્ય જણ વો.

Q.2 (a) State the points to be considered while applying the voltage to the 03

2/3

transformer first time.

પ્રશ્ન. ર (અ) ટ્ર ટસફોમમરને િથમ વખત વોલ્િેજ આપત ાં પહલે ાં ધ્ય નમ ાં ર ખવ મ ાં આવત ાં મ દ્દ ઓ જણ વો.

૦૩

OR

(a) State the troubles may arise if the load on the transformer is given suddenly. 03

(અ) ટ્ર ટસફોમમરને અચ નક લોડ કરવ મ ાં આવે તો ઉદ્દભવતી મ શ્કેલીઓ જણ વો. ૦૩

(b) List the commissioning tests on power transformer. 03

(બ) પ વર ટ્ર ટસફોમમર પર કરવ મ ાં આવત કપ્રમશપ્રનિંગ િે્િ જણ વો. ૦૩

OR

(b) Explain the loading procedure of power transformer.

03

(બ) પ વર ટ્ર ટસફોમમરન લોટડિંગની િટિય સમજાવો. ૦૩

(c) List the data required for determining the economical value of the preventive

maintenance and steps are followed to determine its NPV. (net present value) 04

(ક) પ્રિવેન્ટિવ મેઇનિેનટસની ઇકોનોપ્રમકલ વેલ્ય શોધવ મ િે જરૂરી ડેિ જણ વો અને તેની NPV (નેિ પ્રિસેિ વેલ્ય ) શોધવ મ િે અન સરવ પડત ્િેપ જણ વો.

૦૪

OR

(c) Explain the activities performed during the breakdown maintenance. 04

(ક) બે્રક ડ ઉન મેઇનિેનટસ દરપ્રમય ન કરવ મ ાં આવતી િવપૃ્રતઓ સમજાવો. ૦૪

(d) Explain causes of audible noise from transformer and measure to reduce it. 04

(ડ) ટ્ર ટસફોમમરન ઓટડબલ નોઇસન ક રણો અને તને ઘિ ડવ ન પગલ ઓ સમજાવો.

૦૪

OR

(d) By giving example explain sensory inspections and study of log records. 04

(ડ) ઉદ હરણની મદદથી સેટસરી ઇટસપેક્શન અને લોગ રેકોડમનો અભ્ય સ સમજાવો.

૦૪

Q.3 (a) Explain the procedure of filling SF6 gas in single pressure puffer type SF6

circuit breaker. 03

પ્રશ્ન. 3 (અ) પ્રસિંગલ િેસર પફર િ ઇપ SF6 સરટકિ બ્રેકરમ ાં SF6 ગેસ ભરવ ની િટિય સમજાવો.

૦૩

OR

(a) Explain how analysis of failure circuit breaker is done. 03

(અ) ફેઇલ્યોર સરટકિબે્રકરન ાં પથૃ્થકરણ કેવી રીતે કરવ મ ાં આવે છે તે સમજાવો. ૦૩

(b) Explain spring open- spring close mechanism for high voltage a.c. circuit

breaker. 03

(બ) હ ઇ વોલ્િેજ એ.સી. સરટકિ બે્રકર મ િે સ્્િિંગ ઓપન સ્્િિંગ ક્લો પ્રમકેપ્રન મ સમજાઓ.

૦૩

OR

(b) Explain the influence of imposed normal duty on maintenance of circuit

breaker. 03

(બ) સરટકિ બે્રકરન મેઇનિેનટસ પર ઇમ્પોઝ્ડ નોમમલ ડય િીની અસર સમજાઓ. ૦૩

(c) Explain post fault maintenance of bulk oil circuit breaker. 04

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(ક) બલ્ક ઓઇલ સરટકિ બે્રકરન ાં પો્િ ફોલ્િ મેઇનિેનટસ સમજાઓ. ૦૪ OR

(c) Explain gas monitoring system and gas handling system for SF6 gas filled

equipment. 04

(ક) SF6 ગેસ ટફલ્ડ ઇસ્ક્વપમેટિ મ િે ગેસ મોપ્રનિટરિંગ પ્રસ્િમ અને ગેસ હટેડઝલિંગ પ્રસ્િમ સમજાવો.

૦૪

(d) State any eight type tests performed on high voltage a.c. circuit breaker and

give its detail in short. 04

(ડ) હ ઇ વોલ્િેજ એ.સી. સરટકિબે્રકર પર કરવ મ ાં આવત ગમે તે આઠ િ ઇપ િે્િ જણ વો અને તેમની ટૂાંકમ ાં મ ટહતી આપો.

૦૪

OR

(d) Explain routine tests performed on high voltage a.c. circuit breaker. 04

(ડ) હ ઇ વોલ્િેજ એ.સી. સરટકિબે્રકર પર કરવ મ ાં આવત ર ટિન િે્િ સમજાવો. ૦૪

Q.4 (a) Explain procedure for dielectric strength test of transformer oil. 03

પ્રશ્ન. ૪ (અ) ટ્ર ટસફોમમર ઓઇલન ડ ઇલેકટટ્રક ્ટે્રટથ િે્િ મ િેની િટિય સમજાવો. ૦૩

OR

(a) Explain working of buchholz relay. 03

(અ) બ કોલ્ રીલેન ાં ક યમ સમજાવો. ૦૩

(b) Explain factors affecting the life of transformer. 04

(બ) ટ્ર ટસફોમમરન આય ષ્યને અસર કરત પટરબળો સમજાવો. ૦૪

OR

(b) What is tap changer? Explain on load tap changing method. 04

(બ) િેપ ચેટજર એિલે શ ાં? ઓન લોડ િેપ ચેનટજિંગ મેથડ સમજાવો. ૦૪

(c) Prepare sheet for maintenance schedule of transformer having capacity below

1000 kVA. 07

(ક) 1000 kVA થી ઓછી કેપેપ્રસટિન ટ્ર ટસફોમમરન મેઇનિેનટસ પ્રશડય લ મ િેની શીિ તૈય ર કરો.

૦૭

Q.5 (a) Explain method of grounding power transformer. 04

પ્રશ્ન. ૫ (અ) પ વર ટ્ર ટસફોમમરન ગ્ર ઉન્ટડિંગની રીત સમજાવો. ૦૪

(b) State safety measures are to be taken while carrying out maintenance of

transformer. 04

(બ) ટ્ર ટસફોમમરન ાં મેઇનિેનટસ કરતી વખતે લેવ મ ાં આવત સલ મતીન પગલ ાં જણ વો.

૦૪

(c) Explain how the voltage ratio of transformer is measured with the help of

ratio meter? 03

(ક) રેપ્રશઓમીિરની મદદથી ટ્ર ટસફોમમરનો વોલ્િેજ રેપ્રશઓ કેવી રીતે મ પી શક ય તે સમજાવો.

૦૩

(d) List the detecting device used in transformer and explain working of pressure

relief valve. 03

(ડ) ટ્ર ટસફોમમરમ ાં વપર ત ટડિેક્િીંગ ટડવ ઇસ જણ વો અને િેસર ટરઝલફ વ લ્વન ાં ક યમ સમજાવો.

૦૩

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

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Seat No.: ________ Enrolment No.___________

GUJARAT TECHNOLOGICAL UNIVERSITY Diploma Engineering - SEMESTER–VI • EXAMINATION – WINTER • 2016

Subject Code: 3360907 Date: 24-10-2016

Subject Name: Maintenance Of Transformer & Circuit Breaker

Time: 10:30 am - 01:30 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 different types of maintenance.

૧. મેઇનટેનન્સન જુદ જુદ પ્રક ર જણ વો,.

2. Explain unscheduled maintenance of transformer.

૨. ટ્ર ન્સફોમમરન ુાં અનશશડ્યલુ્ડ્ મેઇનટેનન્સ સમજાવો.

3. Why one minute megger reading always higher always the initial reading?

૩. એક શમશનટ મેગર રરરડ્િંગ શરુઆતન રરરડ્િંગ કરત ાં શ મ ટે હાંમેશ વધ રે હોય છે?

4. Write the abbreviations of (i) BDV (ii) PI (iii) CTC (iv) OLTC

૪. પરૂ ન મ આપો. (i) BDV (ii) PI (iii) CTC (iv) OLTC

5. What are the check points during inspection of surge diverter and relay?

૫. સર્જ ડ્ ઇવટમર અને રીલેન ઇન્સપેક્શન દરશમય નન ચેક પોઇન્ટસ કય છે?

6. Explain absorption co-efficient.

૬. એબસોબમશન કો-ઇરફશસઅન્ટ સમજાવો.

7. Which information can be obtained by performing magnetizing current test

on power transformer?

૭. પ વર ટ્ર ન્સફોમમર પર મેગ્નેટ ઇંગિંગ ટેટ ટ કરવ થી કઇ મ રહતી મેીવી શક ય છે?

8. State the purpose of millivolt test on a circuit breaker.

૮. સરરકટ બે્રકર પર કરવ મ ાં આવત શમલી વોલ્ટ ટેટ ટનો હતે ુજણ વો.

9. List only the name of routine maintenance tests to be performed on the

moulded case circuit breaker.

૯. મોલ્ડે્ડ્ કેસ સરરકટ બે્રકર પર કરવ મ ાં આવત રુરટન મેઇનટેનન્સ ટેટ ટન મ ત્ર

ન મ આપો.

10. Give the name of components to be checked during maintenance of ABCB.

૧૦. ABCBન મેઇનટેનન્સ દરશમય ન ચેક કરવ મ ાં આવત કોમ્પોનન્ટન ન મ જણ વો.

Q.2 (a) Give different sources of noise generation in transformer, its effect and

remedial measures to remove it.

03

પ્રશ્ન. ર (અ) ટ્ર ન્સફોમમરમ ાં નોઇસ ઉત્પન કરત ાં જુદ જુદ સોસમ, તેની અસર અને તેને દૂર ૦૩

2/3

કરવ ન ઉપ યો જણ વો. OR

(a) Explain the procedure of testing of breakdown voltage of transformer oil. 03

(અ) ટ્ર ન્સફોમમર ઓઇલન બ્રેક ડ્ ઉન વોલ્ટેજન ટેસટ ટિંગની પ્રરિય સમજાવો. ૦૩

(b) List out accessories in large distribution transformer. 03

(બ) લ ર્જ રડ્સટ ટ્રબ્યશુન ટ્ર ન્સફોમમરની એસેસરીગની ય દી બન વો. ૦૩

OR

(b) Give the possible check points during routine daily inspection of power

transformer. 03

(બ) પ વર ટ્ર ન્સફોમમરન રુરટન ડે્ઇલી ઇન્સપેક્શન દરશમય નન શક્ય ચેક પોઇન્ટસ જણ વો.

૦૩

(c) Explain predictive maintenance. State its advantages and disadvantages. 04

(ક) શપ્રરડ્સક્ટવ મેઇનટેનન્સ સમજાવો. તેન ફ યદ ઓ અને ગેરફ યદ ઓ જણ વો. ૦૪

OR

(c) State and explain activities performed during preventive maintenance. 04

(ક) શપ્રવેસન્ટવ મેઇનટેનન્સ દરશમય ન કરવ મ ાં આવતી પ્રવશૃતઓ જણ વો અને સમજાવો.

૦૪

(d) Explain the factors affecting the life of transformer. 04

(ડ્) ટ્ર ન્સફોમમરની લ ઇફને અસર કરત ાં પરરબીો સમજાવો. ૦૪

OR

(d) Explain the significance of maintenance of power transformer. 04

(ડ્) પ વરટ્ર ન્સફોમમરન મેઇનટેનન્સનુાં મહત્વ સમજાવો. ૦૪

Q.3 (a) Explain daily maintenance schedule for transformer above 1000kVA ratings. 03

પ્રશ્ન. 3 (અ) 1000kVAથી ઉપરન રેરટિંગન ટ્ર ન્સફોમમર મ ટે ડે્ઇલી મેઇનટેનન્સ શશડ્યલુ સમજાવો.

૦૩

OR

(a) Explain various causes of troubles and failures of cores. 03

(અ) કોરન ફેઇલ્યરુ અને ઉદ્ ભવતી મશુ્કેલીન જુદ જુદ ક રણો સમજાવો. ૦૩

(b) Explain the maintenance procedure of buchholz relay. 03

(બ) બકુોલ્ગરીલેની મેઇનટેનન્સ પ્રરિય સમજાવો. ૦૩

OR

(b) Explain the maintenance procedure of breather. 03

(બ) ંબ્રધરની મેઇનટેનન્સ પ્રરિય સમજાવો. ૦૩

(c ) Explain voltage ratio test for a transformer. 04

(ક)

ટ્ર ન્સફોમમર મ ટે વોલ્ટેજ રેશશઓ ટેટ ટ સમજાવો.

૦૪

OR

(c) List out various commissioning tests on a power transformer. 04

(ક) પ વર ટ્ર ન્સફોમમર પર કરવ મ ાં આવત જુદ જુદ કશમશશનિંગ ટેટ ટ જણ વો. ૦૪

(d) Explain the procedure for energizing of the power transformer. 04

(ડ્) પ વર ટ્ર ન્સફોમમરને એનજામ ઇગીંગ કરવ મ ટેની પ્રરિય સમજાવો. ૦૪

OR

(d) Classify routine test, type test and special test on a transformer. 04

3/3

(ડ્) ટ્ર ન્સફોમમરન રુરટન ટેટ ટ, ટ ઇપ ટેટ ટ અને ટ પેશશયલ ટેટ ટનુાં વગીકરણ કરો. ૦૪

Q.4 (a) List out the different types of tests performed on high voltage a.c. breaker. 03

પ્રશ્ન. ૪ (અ) હ ઇ વોલ્ટેજ એ.સી. સરરકટ બે્રકર પર કરવ મ ાં આવત જુદ જુદ પ્રક રન ટેટ ટની ય દી બન વો.

૦૩

OR

(a) Explain maintenance steps for the following component of circuit breaker.

(i) Contacts (ii) operating mechanism (iii) relay. 03

(અ) સરરકટ બ્રેકરન નીચે જણ વેલ કોમ્પોનન્ટ મ ટે મેઇનટેનન્સ ટ ટેપ સમજાવો. (i) કોન્ટેકટસ (ii) ઓપરેરટિંગ શમકેશનગમ (iii) રીલ.ે

૦૩

(b) Explain maintenance procedure of vacuum circuit breaker. 04

(બ) વેક્યમુ સરરકટ બે્રકરની મેઇનટેનન્સ પ્રરિય સમજાવો. ૦૪

OR

(b) Explain maintenance procedure of air blast circuit breaker. 04

(બ) એર બ્લ ટ ટ સરરકટ બ્રેકરની મેઇનટેનન્સ પ્રરિય સમજાવો. ૦૪

(c) Explain maintenance of moulded case circuit breaker. 07

(ક) મોલ્ડે્ડ્ કેસ સરરકટ બે્રકરનુાં મેઇનટેનન્સ સમજાવો. ૦૭

Q.5 (a) How monitoring and handling of SF6 gas is carried out in SF6 circuit breaker? 04

પ્રશ્ન. ૫ (અ) SF6 સરરકટ બ્રેકરમ ાં SF6 ગેસનુાં મોશનટરીંગ અને હને્ડ્ંલિંગ કેવી રીતે કરવ મ ાં આવે છે?

૦૪

(b) What are the effects of heavy duty and light duty on the performance of high

voltage circuit breaker? 04

(બ) હ ઇ વોલ્ટેજ સરરકટ બે્રકરન પરફોમમન્સ પર હવેી ડ્યટુી અને લ ઇટ ડ્યટુીની શુાં અસર થ ય?

૦૪

( c ) Prepare trouble shooting chart for the circuit breaker. 03

(ક) સરરકટ બ્રેકર મ ટેનો ટ્રબલ શરૂટિંગ ચ ટમ તૈય ર કરો. ૦૩

(d) What are the causes of failure of circuit breaker? 03

(ડ્) સરરકટ બ્રેકરન ફેલ થવ ન ક રણો જણ વો. ૦૩

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Seat No.: ________ Enrolment No.______________

GUJARAT TECHNOLOGICAL UNIVERSITY DIPLOMA ENGINEERING – SEMESTER – VI• EXAMINATION – SUMMER 2016

Subject Code: 3360907 Date: 16/05/2016 Subject Name: Maintenance of Transformer & Circuit Breaker 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. દશમાથંી કોઇપણ સાતના જવાબ આપો. 14

1. Why life of contacts in vaccum circuit breaker is higher as compare to other circuit breakers?

૧. બી� સક�ટ બ્કેની સેસામણીમા ંવ્વમે સક�ટ બ્કેના કોાટકોટસટે ંઆસેુ ં

શા માટક વધા કે હોં છ્?

2. Write the names of type tests performed on transformer. ૨. ટાાસનોમફે પે કેવામા ંઆવતા ટાઇપ ટકસટના નામ સો.

3. Write effect of temperature on insulation resistance of transformer. ૩. ટાાસનોમફેના ઇાસસ ્ેટ્� કેટીસટાસ ીપે તાપમાનની ાસે સો.

4. Write permissible oil temperature and hot spot temperature of winding for power transformer.

૪. પાવે ટાાસનોમફે માટક પેમીશીબ ીઇ ટકલપ કેમે તથા વાઇા ્�ના હોટ

સપોટ ટકલપ કેમે સો.

5. What is the function of pressure relief valve in transformer? ૫. ટાાસનોમફેમા ંમ્સે ેર ીન વાલવટે ંકામ ુે ંછ્?

6. Why heaters are kept with SF6 circuit breaker in cold regions? ૬. ઠં ા મદકશોમા ંSF6 સક�ટ બ્કે સાથ્ હરટે શા માટક ેાસવામા ંઆવ્ છ્?

7. Why megger reading after 60 seconds is higher than initial megger reading? ૭. ૬૦ સ્કા્સ બાદ મ્�ે ેર ્� શા માટક શ આતના મ્�ે ેર ્� કેતા

વધા કે હોં છ્?

8. Write functions of Buchholz relay in transformer. ૮. ટાાસનોમફેમા ંમકેોટ ેર ્ટ ે ંકા ફં સો.

9. Give causes of low value of insulation resistance of electrical equipment. ૯. ઇ ્ોટરક સાધનના ઇાસસ ્ેશન કેટીસટાસ ીછા થવાના કાેણો આપો.

10. Write the effect of oxygen on life of transformer. ૧૦. ી�ોસજનની ટાાસનોમફેના આસેુ ં પેની ાસે સો.

Q.2 (a) Explain millivolt drop test related to contacts in circuit breaker. 03 પ્. ર (ા) સક�ટ બ્કેમા ંકોાટકોસ સ ં ન લમ્ વોલટ વોપ ટકસટ સમ�વો. ૦૩

OR (a) Write test records related to insulation resistance measurement test of three

phase transformer. 03

(ા) થી નકટ ટાાસનોમફે માટક ઇાસસ ્ેશન ાવેોધ માપન ટકસટ સ ં ન ટકસટ કેકો ફ

સો.

૦૩

(b) Explain procedure of filling SF6 gas in SF6 circuit breaker. 03 (બ) SF6 સક�ટ બ્કેમા ંSF6 �્સ ભેવાની ેરત વણફવો. ૦૩ OR (b) Explain method to check simultaneous contacts closing of three phase circuit

breaker. 03

(બ) થી નકટ સક�ટ બ્કેના કોાટકોટસ સાથ્ બધં થવાની મકાસણી કેવાની ેરતટે ં

વણફન કેો.

૦૩

(c) Write annual maintenance schedule of transformer having capacity up to 1000 kVA.

04

(ક) ૧૦૦૦ કક.વી.એ કમતા ાધેીના ટાાસનોમફે માટક વાલ વક મ્ઇાટકનાસ શી ્ ે

સો.

૦૪

OR (c) Draw the diagram of centrifugal purifier for transformer oil. 04 (ક) ટાાસનોમફે ીઇ માટક સ્ાટરનર�ે ગસેે રનાંેનો ાંાડામ દોેો. ૦૪ (d) Distinguish between off circuit tap switch and on load tap changer. 04 ( ) ીન ો ટકપ સવીમ ાન્ ીન ો ટકપ મ્ાજે વ મ્નો તનાવત જણાવો. ૦૪ OR (d) Write maintenance procedure for interrupter of SF6 circuit breaker. 04 ( ) SF6 સક�ટ બ્કેના ઇાટેગટેની મ્ઇાટકનાસ મોસીજે સો. ૦૪ Q.3 (a) Explain crackle test for transformer oil. 03

પ્. 3 (ા) ટાાસનોમફે ીઇ માટકનો �કક ટકસટ સમ�વો. ૦૩ OR (a) Describe continuity test for transformer. 03 (ા) ટાાસનોમફે માટકનો કાટરાસટેર ટકસટ વણફવો. ૦૩ (b) Explain any one method to find out winding resistance of transformer. 03

(બ) ટાાસનોમફેનો વાઇા ્� ાવેોધ માપવાની એક ેરતટે ંવણફન કેો. ૦૩ OR (b) Write safety precaution for maintenance of circuit breaker. 03 (બ) સક�ટ બ્કેના મ્ઇાટકનાસ માટક સ્નટર સ ં ન સાવમ્તીી જણાવો. ૦૩ (c) Explain maintenance procedure of air blast circuit breaker. 04 (ક) એે બ ાસટ સક�ટ બ્કે માટક મ્ઇાટકનાસ મોસીટેટે ંવણફન કેો. ૦૪ OR (c) Write any four important check points before charging power transformer. 04 (ક) ટાાસનોમફેન્ માે કેતા પહક ા ા�ાંના મ્ક્�ના �દેાી સો. ૦૪ (d) Write reasons of failure of core in transformer. 04 ( ) ટાાસનોમફેના કોે સેાબ થવાના કાેણો સો. ૦૪ OR (d) Write causes of audible noise generation from transformer. 04 ( ) ટાાસનોમફેમા ંી રબ નોઇસ પ્દા થવાના કાેણો સો. ૦૪ Q.4 (a) Write advantages of neutral grounding of transformer. 03

પ્.

૪

(ા) ટાાસનોમફેના ાસટે ડાીા ર�ના નાંદાી સો. ૦૩

OR (a) Explain significance of preventive maintenance. 03 (ા) મીવ્ાટરવ મ્ઇાટકનાસટે ંમહાવ વણફન કેો. ૦૩ (b) Write any four causes of failure of circuit breaker. 04 (બ) સક�ટ બ્કે નકઇલંે થવાના કોઇ પણ માે કાેણો સો. ૦૪ OR (b) Write short note on break down maintenance. 04 (બ) બ્ક ાીન મ્ઇાટકનાસ લવશ્ વશંક નંધ સો. ૦૪ (c) Write reason for failure of distribution transformer and remedial measures

for them. 07

(ક) રસટરબસશેન ટાાસનોમફેમા ંનોલટ થવાના કાેણો ાન્ ત્ન્ અશે કેવા માટકના

ામેનો સો.

૦૭

Q.5 (a) Enlist various commissioning test performed on high voltage AC circuit breaker.

04

પ્.

૫

(ા) હાઇ વોલટકજ એ.સી. સક�ટ બ્કે પે કેવામા ંઆવતા ાેદા ાેદા કલમશન્�

ટકસટની ંાદર સો.

૦૪

(b) Write methods for noise reduction in transformer. 04 (બ) ટાાસનોમફેમા ંનોઇસ ોટા વાની ેરતટે ંવણફન કેો. ૦૪ (c) Explain SF6 gas monitoring system in SF6 circuit breaker. 03

(ક) SF6 સક�ટ બ્કેમા ંSF6 સક�ટ બ્કે SF6 �્સ મોનીટે્� સીસટમ વણફવો. ૦૩ (d) Explain functions of breather and conservator in transformer. 03 ( ) ટાાસનોમફેમા ંબીધે ાન્ કાટેવ્ટેના કાંરટ ે ંવણફન કેો. ૦૩

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