i

ELECTRICAL CHARACTERISTICS OF NEWLY DEVELOPED POLYVINYL CHLORIDE WITH SILICA FILLER FOR HIGH VOLTAGE OUTDOOR INSULATION APPLICATION

SITI SOLEHA BINTI AB GHANI

UNIVERSITI TEKNOLOGI MALAYSIA

i PSZ 19:16 (Pind. 1/07)

UNIVERSITI TEKNOLOGI MALAYSIA DECLARATION OF THESIS/UNDERGRADUATE PROJECT PAPER AND COPYRIGHT

Author’s full name

: SITI SOLEHA BINTI AB GHANI

Date of birth

: 16th MAY 1990

Title

: ELECTRICAL CHARACTERISTICS OF NEWLY DEVELOPED POLYVINYL CHLORIDE WITH SILICA FILLER FOR HIGH VOLTAGE OUTDOOR INSULATION APPLICATION

Academic Session

: 2012/2013

I declare that this thesis is classified as:

CONFIDENTIAL (Contained confidential information under the Official Secret Act 1972)*

⁄

RESTRICTED

(Contains restricted information as specified by the organization where research was done)

OPEN ACCESS

I agree that my thesis to be published as online open access (full text).

I acknowledge that Universiti Teknologi Malaysia reserves the right as follows: 1. The thesis is property of UniversitI Teknologi Malaysia 2. The Library of Universiti Teknologi Malaysia has right to make copies for the purpose of research only. 3. The Library has the right to make copies of the thesis for academic exchange. Certified by:

________________________ SIGNATURE

900516-01-5048 (NEW IC NO./PASSPORT NO.) Date: 18 JUNE 2013 NOTES:

*

_______________________ SIGNATURE OF SUPERVISOR ASSOC. PROF. DR. MOHD MUHRIDZA BIN YAACOB NAME OF SUPERVISOR Date: 18 JUNE 2013

if the thesis is CONFIDENTAL or RESTRICTED, please attach with the letter from the organization with period and reasons for confidentiality or restriction.

i

SUPERVISOR DECLARATION

“I hereby declare that I have read this thesis and in my opinion this thesis have already accomplish with the required scope and quality for the Degree of Bachelor of Electrical Engineering (Power)”

Signature

: …………………………………….

Name

: ASSOC. PROF. DR. MOHD MUHRIDZA YAACOB

Date

: 18 JUNE 2013

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ELECTRICAL CHARACTERISTICS OF NEWLY DEVELOPED POLYVINYL CHLORIDE WITH SILICA FILLER FOR HIGH VOLTAGE OUTDOOR INSULATION APPLICATION

SITI SOLEHA BINTI AB GHANI

Submitted to the Faculty of Electrical Engineering in partial fulfillment for the degree award of Bachelor of Electrical Engineering (Power)

Faculty of Electrical Engineering Universiti Teknologi Malaysia

JUNE 2013

ii

DECLARATION

I declare that this thesis entitled “ELECTRICAL CHARACTERISTICS OF NEWLY DEVELOPED POLYVINYL CHLORIDE WITH SILICA FILLER FOR HIGH VOLTAGE OUTDOOR INSULATION APPLICATION” is the result of my own research except as cited in the references. The thesis has not been acknowledged for any degree and is not concurrently submitted in candidature of any other degree.

Signature

: …………………………………………

Name

: SITI SOLEHA BINTI AB GHANI

Date

: 18 JUNE 2013

iii

DEDICATION

Dedicated to my beloved family, friends and lecturers for their never-ending support, encouragement, and understanding towards the completion of my work.

iv

ACKNOWLEDGEMENT

Firstly, my biggest thanks to Allah S.W.T who gave me the opportunity in doing this project and always giving me hope and ways in completing the tasks.

My great appreciation goes to my supervisor, Assoc. Prof. Dr. Mohd Muhridza Yaacob for his guidance, knowledge, skill, and patience in helping his final year students for the two semesters.

I also want to give my appreciation to other lecturers, technicians, and friends who are willing to help me whether directly or indirectly in completing this final year project. Their good deed will always be remembered.

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ABSTRACT

Polymer composite material is an insulator used for high voltage outdoor insulation. It is made up from polyvinyl chloride (PVC) mixed with fillers. The purpose of this study is to search for filler that can be used with polymer and to study whether different percentage of filler will affect its electrical characteristics. Material searching is based on its good reputation on electrical characteristic, hydrophobicity, resistance to tracking and erosion, resistance to flammability and other factors. The material that has been chosen is silica which is also known as a good insulator. After the filler material was confirmed, the preparation was done at IRM that has the facilities needed to finish the sample preparation. Samples that have been prepared were pure PVC, PVC with 15% silica, PVC with 25% silica, and PVC with 35% silica. After that, electrical tests were done to the polymer composite and pure PVC. The electrical tests involved were dielectric strength test, tan delta test, and capacitance test. Then, insulators undergo ageing process (tracking and erosion test) and redo the electrical test after ageing. The electrical properties of polymer with filler are compared with the pure PVC. The result from this study shows that each insulator undergo degradation during ageing process as each electrical properties reduce after ageing process. Adding small percentage of silica filler seems to reduce the degradation effect on insulator. But, adding too much filler would not help in ageing process because the percentage differ for electrical properties before and after ageing for PVC with 35% silica filler is high.

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ABSTRAK

Komposit polimer adalah penebat yang digunakan untuk penebatan luar voltan tinggi. Ianya terdiri daripada polivinil klorida (PVC) dicampur dengan bahan pengisi yang lain.

Tujuan kajian ini adalah untuk mencari pengisi yang boleh

digunakan dengan polimer dan untuk mengkaji sama ada peratusan bahan pengisi yang berbeza akan mempengaruhi sifat penebat tersebut. Mencari bahan pengisi adalah berdasarkan kepada reputasinya yang baik terhadap ciri-ciri seperti hidrofobisiti, ketahanan kepada hakisan, ketahanan daripada terbakar dan faktorfaktor lain. Bahan yang telah terpilih adalah silika yang juga telah sedia maklum sebagai penebat yang baik. Selepas bahan pengisi telah disahkan, penyediaan sampel telah dilakukan di IRM yang mempunyai kemudahan yang diperlukan untuk menyediakan sampel. Sampel yang telah disediakan adalah PVC tanpa pengisi, PVC dengan 15% pengisi silika, PVC dengan 25% pengisi silika, dan PVC dengan 35% pengisi silika. Selepas itu, ujian-ujuan telah dilakukan untuk PVC dengan pengisi silica dan PVC tanpa pengisi.

Ujian-ujian yang terlibat adalah ujian kekuatan

dielektrik, ujian tan delta, dan ujian kapasitan. Kemudian, penebat menjalani proses penuaan (ujian hakisan) dan ujian-ujian sebelumnya dibuat semula selepas penuaan. Ciri-ciri elektrik penebat PVC dengan pengisi silica dibandingkan dengan penebat PVC tanpa pengisi. Hasil daripada kajian ini menunjukkan bahawa setiap penebat mengalami degradasi semasa proses penuaan kerana setiap sifat-sifat elektrik bahan penebat berkurang selepas proses penuaan. Penambahan peratusan kecil pengisi silika sepertinya dapat mengurangkan kesan proses penuaan pada penebat. Tetapi, penambahn terlalu banyak pengisi tidak akan membantu mengurangkan kesan proses penuaan kerana peratusan yang berbeza untuk sifat-sifat elektrik sebelum dan selepas penuaan untuk PVC dengan 35% pengisi silika adalah tinggi.

vii

TABLE OF CONTENTS

CHAPTER

1

2

TITLE

PAGE

TITLE

i

DECLARATION

ii

DEDICATION

iii

ACKNOWLEDGEMENT

iv

ABSTRACT

v

ABSTRAK

vi

TABLE OF CONTENTS

vii

LIST OF TABLES

x

LIST OF FIGURES

xi

LIST OF SYMBOLS

xii

LIST OF ABBREVIATIONS

xiii

LIST OF APPENDICES

xiv

INTRODUCTION 1.1

Background

1

1.2

Problem Statement

2

1.3

Objective of Project

2

1.4

Scope of Project

2

1.5

Thesis Outline

3

LITERATURE REVIEW 2.1

Polymer Insulation

2.2

Optimization of Dielectric Strength of Polymeric

5

Composite Insulation Using Response Surface Methodology

6

viii

2.3

Dielectric Property of Waste Tyre Dust-Polypropylene (WTD-PP) Composite for High Voltage Outdoor Insulation Application

2.4

Polymer Composite Based on Waste Material for High Voltage Outdoor Application

2.5

6

7

Electrical Characteristics of Polyvinyl Chloride with Wollastonite Filler for High Voltage Outdoor Insulation Material

2.6

7

Classification of Polymeric Insulating Surface Condition Based on Leakage Current Total Waveform Distortion

2.7

2.8

2.9

3

Selection Guide for Polymeric Materials for Outdoor use Under HV Stress

9

Accelerated Ageing Test for Polymeric Materials

10

2.8.1

10

Tracking Test

Breakdown field strength

11

METHODOLOGY 3.1

Project Methodology

12

3.2

Preparation of Test Sample

14

3.2.1

15

Sample Preparation Procedure

3.3

Experimental Setup

20

3.4

Dissipation factor and Capacitance

21

3.4.1

Apparatus

21

3.4.2

Procedure

22

3.5

4

8

Breakdown Voltage

23

3.5.1

Apparatus

23

3.5.2

Procedure

23

RESULT AND DISCUSSION 4.1

Introduction

26

4.2

Result

26

4.2.1

Dissipation Factor

27

4.2.2

Capacitance

28

ix

4.2.3 4.3

5

Breakdown Voltage

29

Discussion

29

4.3.1

Dissipation Factor

30

4.3.2

Capacitance

31

4.3.3

Breakdown Voltage

33

CONCLUSION AND RECOMMENDATION 5.1

Conclusion

35

5.2

Recommendation

36

REFERENCES

37

APPENDICES

40

x

LIST OF TABLES

TABLE NO. 2.1

TITLE The properties of polymeric insulation for outdoor

PAGE 9

use under HV stress 3.1

Categories of samples

14

4.1

Dissipation factor value of five samples for each category 27

4.2

Capacitance value of five samples for each category

28

4.3

Breakdown voltage value in kV/cm

29

xi

LIST OF FIGURES

FIGURE

TITLE

PAGE

2.1

Schematic circuit diagram for inclined-plane-test

11

3.1

Summarize of project methodology

13

3.2

Procedure of preparing samples

15

3.3

Weighing process

16

3.4

Roll-mill machine

17

3.5

Sheet of composite material

17

3.6

Sheets of materials stacked together

18

3.7

Materials in moulding plate

18

3.8

Hot press machine

19

3.9

Experimental Setup for Inclined Plane Test

20

3.10

Tettex Instrument Bridge 2816 setup

21

3.11

Dissipation factor and capacitance test

22

3.12

Dielectric strength test setup

24

3.13

Actual dielectric strength test setup

24

3.14

Breakdown in the sample

25

4.1

Average value of dissipation factor (tan delta) before and

30

after ageing 4.2

Average value of capacitance before and after ageing

32

4.3

Breakdown voltage of samples

34

xii

LIST OF SYMBOLS

kV

-

kilo volt

pF

-

pico farad

δ

-

Delta

⁰C

-

degree Celsius

pph

-

part per hundred

Hz

-

Hertz

xiii

LIST OF ABBREVIATIONS

PVC

-

Polyvinyl Chloride

IRM

-

Industrial Resins Malaysia

IVAT

-

Institut Voltan dan Arus Tinggi

UTM

-

Universiti Teknologi Malaysia

RSM

-

Response Surface Methodology

ANOVA

-

Analysis of Variance

WTD

-

Waste Tyre Dust

PP

-

Polypropylene

EAP

-

Early aging period

TP

-

Transition period

LAP

-

Late aging period

HV

-

High voltage

UV

-

Ultra violet

IEC

-

International Electromechanical Commission

xiv

LIST OF APPENDICES

APPENDIX

TITLE

PAGE

A

British Standard EN 62039:2007/IEC 62039:2007

40

B

British Standard EN 60587:2007

54

1

CHAPTER 1

INTRODUCTION

1.1

Background

There are many types of insulator used for high voltage application. Some of them are ceramic, porcelain, glass, and polyvinyl chloride (PVC).

However,

polymer composite material is more favorable to use as an outdoor insulation material. This is because polymer composite material has several advantages compared to other materials which are of lighter weight, high mechanical strength, and better performance in polluted condition [1].

Polymer composite material

consists of fillers mixed with polymer. In this study, filler will be selected and the electrical properties of the polymer composites will be tested before and after the inclined-plane tracking and erosion test. This process is crucial to determine the long term reliability of the new polymer composite insulator.

2

1.2

Problem Statement

Current outdoor high voltage insulators such as ceramic, porcelain, and glass are expensive and heavy and its electrical characteristic often reduces after several years. Therefore, new polymer composite insulator with fillers consists of recycled material is being studied to overcome this problem.

1.3

Objective of Project

The objectives of this study are as follow:

•

To study new polymer composite insulator for outdoor high voltage application.

•

To conduct the long term reliability and electrical tests on the new insulation material.

•

To compare the electrical properties of the polymer composite insulator with pure polyvinyl chloride insulator.

1.4

Scope of Project

The scopes of this study are listed as follow: 1. Preparation of materials was done at Industrial Resin Malaysia (IRM). 2. Tests conducted were inclined-plane tracking and erosion test, breakdown test, tan delta and capacitance test. 3. Electrical test was conducted at IVAT laboratory, UTM.

3

1.5

Thesis Outline

This Final Year Project Thesis consists of five chapters in total.

These

chapters include introduction about the research, literature review, research methodology that used, results obtained, discussion and recommendation.

First, Chapter 1 is the introduction part in this thesis. To introduce the research to readers, research background was explained briefly. Then, statement of problem in the industry studied in the research and its objectives were stated. Furthermore, types of tests used are described in the scope of the research.

Chapter 2 is about literature review. In this chapter, previous researches that have been done related to this study were discussed. The theoretical base of the research used also discussed further.

Chapter 3 covered on methodology of the research. The flows of steps took are represented by the flow chart in this chapter. One of the step is preparation of raw materials until it become the test sample used in experimental tests. There are also experimental setup and procedure for inclined plane test, breakdown, and tan delta test.

Chapter 4 show the results obtained from the experiment. The results are represented in tables and bar chart to make it easy to understand and make comparison. The results then are discussed further.

4

Chapter 5 is about conclusion of the research and what has been obtained from the research. Then proposed ways and some recommendations to improve the research in the future were discussed.

5

CHAPTER 2

LITERATURE REVIEW

2.1

Polymer Insulation

Polymer product as insulation is still new in the industry when compared to porcelain. Usually, polymer do not achieve the expected lifetime from its developer. This is due to surface damage and ageing from constant exposure even though it shows good wet resistant initially [1].

Past research about polymer insulation had list down the steps for polymer flashover and effects of ageing [1]. First, contamination build-up at the surface of insulator wets due to fog and rain and wetting of the dry residual due to droplet forms conductive layer. Then, ohmic heating occurs that is heating from leakage current flow, electric field effect, spot discharge on the surface, and reduction of the hydrophobicity. Dry bands will form causing surface erosion. The repetition of these cycles will eventually make the surface of the insulator become hydrophilic and flashover can occur.

6

2.2

Optimization of Dielectric Strength of Polymeric Composite Insulation Using Response Surface Methodology

A research involved newly developed polymeric composite for high voltage application has been done. Since polymeric composite insulators are used widely in the industry, many studies have been conducted to develop and investigate its performance. The study involved polypropylene as a matrix and commercial wollastonite as a filler with addition of alumina trihydrate as anti- tracking and erosion for the polymer composite. Using response surface methodology (RSM), mathematical correlation between filler parameters can be developed to get optimum dielectric strength. ANOVA technique is used to validate the developed model. By using RSM, number of samples with specific ratio that has to be made is reduced. Screening and optimization process are sufficient in their study to come up with equation that can predict optimum dielectric strength with accuracy of 91.04%. The optimum criterion for artificial wollastonite is 20 % with alumina trihydrate 100 part per hundred (pph) [2].

2.3

Dielectric Property of Waste Tyre Dust-Polypropylene (WTD-PP) Composite for High Voltage Outdoor Insulation Application

This is a summary of a study about dielectric property of WTD-PP composite. The study focused on whether there is probability in using waste tyre dust as reinforcement filler with addition of alumina trihydrate. Waste tyre dusts are obtained from processing scrap tyre. Aluminum trihydrate is used to improve flammability properties in terms of tracking and erosion resistance and ageing. 16 types of composition are made to find maximum effectiveness. Dielectric strength test is conducted to see the performance of WTD-PP composite. The result shows that all samples for WTD-PP composite do not pass minimum requirement for

7

polymeric insulator because the present of black carbon in WTD as anti-abrasive for tyre. That reduces volume resistivity as well as dielectric strength of insulator [3].

2.4

Polymer Composite Based on Waste Material for High Voltage Outdoor Application

This study intended to review potential of waste material as filler to polymeric insulator. Materials involved in this study are seashell which is mainly calcium carbonate, soda-lime glass which is mainly silica, and polypropylene. Alumina Trihydrate is also used as filler. Using response surface methodology and dielectric strength test, artificial wollastonite that have similar characteristic as natural wollastonite can be produced. The ratio of waste glass and seashell for artificial wollastonite are 51.7 and 48.3 wt% and 1000⁰C for calcinations. With this study, artificial wollastonite has successfully been developed using waste glass and seashell [4].

2.5

Electrical Characteristics of Polyvinyl Chloride with Wollastonite Filler for High Voltage Outdoor Insulation Material

This paper investigated about whether the use of wollastonite filler in PVC insulator will reduce the effect of ageing and whether the new developed artificial wollastonite has the same effect as commercial wolastonite as a filler or not. Samples that have been prepared are pure PVC, PVC + artificial wollastonite, and PVC + commercial wollastonite. Surface tracking and erosion test is conducted to determine surface resistant to tracking and erosion. Tangent delta and capacitance test was conducted to determine their insulation properties and dielectric strength test

8

to determine their breakdown voltage. From their findings, ageing process degraded the insulator and reduces its performance such as dissipation factor, capacitance, insulation resistance, and breakdown voltage. Meanwhile, adding filler improves certain characteristic of insulator.

Therefore, it was proven that PVC with

wollastonite filler can be used as high voltage outdoor insulation material [5].

2.6

Classification of Polymeric Insulating Surface Condition Based on Leakage Current Total Waveform Distortion

Another study used linear time-distribution technique and spectrogram implemented to estimate leakage current parameters. For experimental work, Incline Plane Test is used. Measuring unit is installed to measure leakage current that flow on the surface of sample during the test and the waveform of the leakage current viewed in computer using LabVIEW software. Leakage current flow are divided to three parts which are early aging period (EAP), transition period (TP), and late aging period (LAP). EAP is when the sample is completely dry and in hydrophobic state. TP is when insulation surface become hydrophilic and leakage current change from capacitive to resistive. LAP is when leakage current becomes completely resistive and surface discharge occurs. From the study, it is found that providing information on frequency component becomes easier with the use of spectrogram in timefrequency representation [6].

9

2.7

Selection Guide for Polymeric Materials for Outdoor use Under HV Stress

Selection of filler for polymeric materials for high voltage outdoor use is based on the British Standard PD IEC/TR 62039:2007. This standard tells about some properties that must be considered before selecting materials. The properties are resistance to tracking and erosion, resistance to corona and ozone, resistance to chemical and physical degradation by water, tear strength, volume resistivity, breakdown field strength, resistance to chemical attack, resistance to weathering and UV, resistance to flammability, arc resistance, glass transition temperature, and hydrophobicity [7]. The summary for material properties and its test standard are shown in Table 2.1.

Table 2.1: The properties of polymeric insulation for outdoor use under HV stress Property

Test standard

Resistance to tracking and erosion

IEC 60587

Resistance to corona and ozone

Under consideration

Resistance to chemical and physical degradation by water

IEC 62217, water diffusion test IEC 60250 (tan δ)

Tear strength

ISO 34-1

Volume resistivity

IEC 60093

Breakdown field strength

IEC 60243-1; IEC 60455-2

Resistance to chemical attack

See IEC 62039 section 3.8

Resistance to weathering and UV

ISO 4892-2 ISO 4892-3

Resistance to flammability

IEC 60695-11-10

Arc resistance

IEC 61621

10

Glass transition temperature

IEC 61006

Hydrophobicity

Under consideration

2.8

Accelerated Ageing Test for Polymeric Materials

The ageing factor for insulator material that should be examined includes electrical stress, environmental stress, and mechanical stress. Electrical stress on insulator may result in partial discharge, leakage current and corona. Environmental stress involves weather change and UV radiation will affect the properties of material. For polymeric material, the accelerated ageing tests are ultraviolet exposure test, tracking test, corona cutting test, and oxidative stability test [8]. However, in this project, only tracking test were done for ageing based on IEC 60587.

2.8.1

Tracking Test

When insulator is exposed to contamination, electrical discharge may occur. For this project, after the insulator has been made at IRM, it will undergo the tracking test or the inclined-plane-test. This test is based on IEC 60587 to determine whether the insulating material can resist from erosion and tracking or not. Method 1 (constant tracking voltage) is used in this test [9]. Distilled water with contamination will be let flown uniformly on the test specimen at the specified rate. Then, the voltage at one end will be increased to the preferred test voltage within 10 seconds.

11

The voltage shall be maintained for 6 hours and the leakage current is viewed using software. The schematic diagram for incline-plane-test is shown in the Figure 2.1.

Components S

power supply switch

VT

variable ratio transformer

T

high voltage transformer

R

series resistor

V

voltmeter

Sp

specimen

F

overcurrent device, fuse or relay Figure 2.1: Schematic circuit diagram for inclined-plane-test

2.9

Breakdown field strength

To determine the dielectric breakdown voltage, IEC 60243-1 standard was used. The test is valid at power frequency between 48 and 62 Hz. The arrangement of dielectric was placed between electrodes.

The voltage difference between

electrodes was then increased until breakdown occurred. The voltage is recorded to be the breakdown voltage of that specific dielectric.

12

CHAPTER 3

METHODOLOGY

3.1

Project Methodology

The methodology for this project includes literature review, search for material, material preparation, and tests. All of them need to be done in the two semester of final year project. Figure 3.1 shows the overall process of this project.

13

Start

Identify the problem

Literature review

Search for material

Rejected

Material confirmation with supervisor Accepted

Material preparation at IRM Conduct electrical test on the insulator before ageing process. Ageing process Pass

Conduct electrical test on the insulator after ageing process. Result and discussion Conclusion End

Figure 3.1: Summary of project methodology

14

3.2

Preparation of Test Sample

The preparation of the sample begins after the raw material has been obtained. Important raw materials in preparing the sample are PVC powder and silica powder.

PVC powder has been purchased from online website named Sigma Aldrich. However, the delivery time for this material is very long.

The silica powder is obtained from recycled glass. The glass is crushed and processed in the ball mill to get its powder form.

The sample is prepared based on categories shown in Table 3.1.

Table 3.1: Categories of samples Sample Name

Content

A

Pure PVC

B

PVC + 15% silica

C

PVC + 25% silica

D

PVC + 35% silica

After that, the raw materials are processed in IRM to make the samples. The processes of making sample are shown in Figure 3.2.

15

Figure 3.2: Procedure of preparing samples

3.2.1

Sample Preparation Procedure

First, the raw materials are weight according to its percentage as shown in Table 3.1.

16

Figure 3.3: Weighing process

Figure 3.3 shows the process of weighing raw materials. After that, the materials were then rolled in the Roll-mill machine to mix the PVC with its filler. This process takes about 5 minutes for each 200 grams of raw materials. The temperature set to this machine is 180⁰C. However, actual temperature at the mill is usually lower than the set temperature because of heat loss. Rolling raw material in the machine with suitable temperature would produce a sheet of composite material.

17

Figure 3.4: Roll-mill machine

Figure 3.4 shows roll-mill machine that is used to mix the materials and produced composite material in the form of thin sheet as shown in Figure 3.5.

Figure 3.5: Sheet of composite material

18

The sheet of composite material then was cut to desired size which is 50mm×120mm. The sheet that had been cut then were stacked together as shown in Figure 3.6 to get its 6mm width.

Figure 3.6:

Sheets of materials stacked together

Then, the stacked materials were put in moulding plate which has the exact same size with sheet of materials that have been cut as shown in Figure 3.7.

Figure 3.7: Materials in moulding plate

19

After that, the plate was pressed in the hot press machine as shown in Figure 3.8. The time taken for this process was about 10 minutes and the materials were let to cool for another minutes before took out from the machine. The temperature set for pressing the material was 180⁰C. However, similar as roll-mill machine, the actual temperature of the hot press machine is usually lower than its set value due to heat loss to surroundings.

Figure 3.8: Hot press machine

After all the procedures have been done for each category of samples, the samples then were complete and ready to be tested.

20

3.3

Experimental Setup

The tests involved in this study are Inclined Plane Test, tan delta test, and dielectric strength test. The experiments were conducted in IVAT laboratory that have all the equipment needed for the tests. According to BS EN 60587:2007, the experimental setup for Inclined Plane Test is as Figure 3.9.

Power Resistor

Pump

Contaminant solution

Inclined sample Variable Transformer

Fuse 50mA

Discharges fuse 90V

Computer

DAQ

Figure 3.9: Experimental Setup for Inclined Plane Test

The test voltage used for this experiment is 3.5 kV and the contaminant flow rate is 0.3 ml/min. After the device is switched on, the voltage should reach 3.5kV within 10 seconds. Then, all parameters should be kept constant for 6 hours. The waveform of leakage current was monitored in the computer using LabVIEW software.

21

3.4

Dissipation factor and Capacitance

Dissipation factor and capacitance test is done before and after the inclined plane test. The procedure and experimental setup for both dissipation factor and capacitance test were the same because it used the same instrument that can measure both parameters. Five samples were tested and the average value of the dissipation factor and capacitance was calculated.

3.4.1

Apparatus

The apparatus involved in this test are Tettex Instrument Bridge 2816, barometer, plane-plane electrodes, electrode stand, and discharge rod. Figure 3.10 shows barometer, and Tettex Instrument Bridge 2816.

Value Display Barometer

Regulator

Transformer

Figure 3.10: Tettex Instrument Bridge 2816

22

3.4.2

Procedure

1. The apparatus was setup as shown in Figure 3.11.

Electrode HV AC/DC Source

Tettex Instrument

Sample

Figure 3.11: Dissipation factor and capacitance test setup

2. The Tettex Instrument is switched on and set to current room temperature according to barometer. 3. The interlock button of Tettex Instrument was hold down and the voltage was increased to 5kV. 4. The run button was pressed. The instrument will feed voltage to sample for 10 cycles before the result come out. 5. The result for dissipation factor and capacitance was recorded. 6. All the steps were repeated for the rest of test samples.

23

3.5

Breakdown Voltage

The breakdown voltage test was done before and after the inclined plane test. Unlike the dissipation factor and capacitance test, breakdown test will only involve one sample before inclined plane test and one sample after that.

3.5.1

Apparatus

The apparatus involved in breakdown test are HV AC/DC generation instrument, HV AC/DC test set meter, point-point electrodes, electrode stand, and discharge rod.

3.5.2

Procedure

1. The apparatus was set up as shown in Figure 3.12 and the actual set up is shown in Figure 3.13.

24

HV AC/DC Test Set Meter

HV AC/DC Generation

Figure 3.12: Dielectric strength test setup

Figure 3.13: Actual dielectric strength test setup

2. HV AC/DC Test Set Meter was turned on and the voltage was increased slowly. 3. When breakdown occurred, the voltage was recorded. The breakdown in the sample is shown in Figure 3.14.

25

Figure 3.14: Breakdown in the sample

4. The voltage was then decreased to 0V and HV AC/DC Test Set Meter was turned off. 5. The apparatus were then discharged. 6. The steps were repeated for remaining test samples.

26

CHAPTER 4

RESULT AND DISCUSSION

4.1

Introduction

After all the tests have been done to the samples, eventually the result will be compared and discussed. In this chapter, the result from tan delta test, capacitance test, and breakdown test will be shown in tables and bar chart. The result will be compared before and after ageing process.

Furthermore, the effect of adding

different percentage of silica filler would also be discussed in this chapter.

4.2

Result

The recorded result for each experiment will be shown in details for each sample before and after ageing. Then, it will be analyzed for better understandings.

27

4.2.1

Dissipation Factor

The result for dissipation factor for each samples were tabulated in Table 4.1.

Table 4.1: Dissipation factor value of five samples for each category A Sample

B

C

D

Before

After

Before

After

Before

After

Before

After

ageing

ageing

ageing

ageing

ageing

ageing

ageing

ageing

1

0.179

0.365

0.185

0.275

0.153

0.264

0.135

o.260

2

0.179

0.329

0.170

0.300

0.150

0.266

0.125

0.242

3

0.212

0.406

0.188

0.281

0.154

0.272

0.122

0.284

4

0.187

0.328

0.171

0.272

0.149

0.275

0.129

0.255

5

0.219

0.321

0.149

0.261

0.140

0.299

0.127

0.246

0.195

0.350

0.173

0.278

0.149

0.275

0.128

0.257

Average Difference (%)

44.3

37.8

45.8

50.2

28

4.2.2

Capacitance

The result for capacitance for each samples were tabulated in Table 4.2.

Table 4.2: Capacitance value of five samples for each category A Sample

B

C

D

Before

After

Before

After

Before

After

Before

After

ageing

ageing

ageing

ageing

ageing

ageing

ageing

ageing

1

36.39

42.87

42.82

49.07

40.16

46.59

38.76

47.09

2

37.70

41.92

38.59

43.50

39.68

45.34

42.16

50.26

3

41.55

48.22

38.06

46.33

36.55

42.82

41.34

51.33

4

36.24

41.13

40.74

47.03

36.91

42.62

39.31

46.51

5

37.20

40.34

41.30

48.34

36.91

37.57

41.05

49.67

Average

37.82

42.90

40.30

46.85

38.04

42.99

40.52

48.97

Difference (%)

11.8

14.0

11.5

17.3

29

4.2.3

Breakdown Voltage

The result for breakdown voltage for each samples were tabulated in Table 4.3.

Table 4.3: Breakdown voltage value in kV/cm Breakdown Voltage (kV/cm) Sample

4.3

Voltage Different

Before

After

tracking

tracking

A

56.7

56.7

0

B

55.0

53.3

0.03

C

56.7

53.3

0.06

D

55.0

53.3

0.03

(%)

Discussion

In this section the results from previous section were discussed. The results from tables are converted to bar chart to ease viewing and analyzing. The difference in value of dissipation factor, capacitance, and breakdown voltage are to be discussed later.

30

4.3.1

Dissipation Factor

The bar chart below shows the dissipation factors for sample A, B, C, and D. Total of five samples were used for each categories of samples. The average value of dissipation factor can be seen in Figure 4.1.

Figure 4.1: Average value of dissipation factor (tan delta) before and after ageing

Figure 4.1 shows that values of dissipation factor for each sample before ageing were small and close to zero. As already been known, for good insulator, it is best to have small value of dissipation factor. Insulation that has high dissipation factor means that it has low insulation quality and one of the factors that lead to high value of dissipation factor is ageing [10]. It is proven when we see that after ageing process, all dissipation factor values of samples rise.

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When comparing the value of dissipation factor for sample A which is pure PVC with sample B, C, and D which are PVC with silica filler, it shows that the average value of dissipation factor for PVC with silica filler is lower than pure PVC regardless the percentage of filler. This means that adding silica to PVC insulator improves its dissipation factor quality.

Although sample D has the lowest value of dissipation factor before and after ageing, the percentage difference of the value before and after ageing is the highest (50.2%). This means that sample D was highly affected by the ageing process as the value rise more than other samples. Samples easily aged with time are not suitable to be insulator because the insulation properties of the insulator will reduce. Sample B has the lowest percentage difference of dissipation factor value before and after ageing (37.8%). This means sample B was not critically affected by ageing process and it is most likely can maintain its insulation properties longer than other sample.

After comparing the values of dissipation factor of four categories of samples, it can be said that adding silica filler to PVC insulator helps in improving its dissipation factor value. Furthermore, 15% of silica filler may reduce the effect of ageing of insulator when compared with other percentage of filler.

4.3.2

Capacitance

For each category of sample A, B, C, and D, the total of five samples for each category undergone the test and the value of capacitance for each sample were recorded. The average values of capacitance then were converted to bar chart in Figure 4.2.

32

Figure 4.2: Average value of capacitance before and after ageing

From Figure 4.2, shows the pattern of capacitance value before and after ageing process. For a good insulation, it is good to have high capacitance value. From the data obtained, the value of capacitance increased for each sample after ageing process.

Surprisingly, ageing process improved some of the insulation

properties which is its capacitance value.

When comparing the value of capacitance of sample A (pure PVC) with sample B, C, and D (PVC with silica filler), we can see that samples B, C, and D have higher capacitance value compare to sample A. It means that adding silica filler also improved capacitance value of the insulator.

When comparing the value of capacitance among samples B, C, and D, it shows that sample D has the highest capacitance value before ageing and also after

33

ageing process. However, in terms of percentage difference value of capacitance, sample D has the highest percentage difference (17.3%). It is the same as before that sample D cannot stand ageing process and it deteriorated faster than other sample as its capacitance value changes the most. Therefore, sample D is not suitable to make an insulator used for long period of time.

The sample with lowest percentage

difference of capacitance value is sample C with value 11.5%. This means sample C can maintain its capacitance value for long period of time.

After comparing capacitance value of the four category of sample, it can be said that adding silica filler do helps in improving the capacitance value of PVC insulator. Furthermore, adding 25% of silica filler seams help in maintaining the capacitance value of insulator after ageing. However, adding too much filler would not help in slowing the ageing process of the insulator.

4.3.3

Breakdown Voltage

Dielectric Strength test is done to know the maximum voltage that certain insulators can stand and the voltage is called breakdown voltage. One sample for each category was tested and the value was represented by Figure 4.3.

34

Figure 4.3: Breakdown voltage of samples

From Figure 4.3, shows that the breakdown voltage for the samples was between 55.0 to 56.7 kV before ageing while after ageing, it change from 53.3 to 56.7kV. It shows that ageing process affected the value of breakdown voltage before ageing for some samples.

Again, when comparing sample A (pure PVC) with sample B, C, and D (PVC with silica filler, sample A and C have the same breakdown voltage value which is 56.7 kV whereas sample B and D have same breakdown voltage which is 55 kV. After ageing process, the value of breakdown voltage for sample A did not change. It is different for sample B, C, and D as the breakdown voltage value decreased after ageing.

This shows that adding silica filler to PVC insulator did not help in

improving its dielectric strength.

35

CHAPTER 5

CONCLUSION AND RECOMMENDATION

5.1

Conclusion

Throughout this study, electrical tests have conducted to the new polymer composite insulator (PVC with silica filler).

The tests are tangent delta test,

capacitance test, and dielectric strength test.

After that, all samples underwent

ageing process and redid all the electrical tests after ageing. This process is important to achieve one of the objectives which are to study the long term reliability of new insulation materials.

After analyzing the results, it was discovered that adding silica filler to PVC insulation can help in improving some of the insulation properties of insulator as the value of capacitance and dissipation factor improved for PVC with silica filler. However the value of breakdown voltage does not improve.

After ageing process, the properties of insulator for each sample decreased showing that there are formations of water tree on the insulation during ageing. Adding silica filler has reduced the effect of ageing on insulator. However, too much

36

filler would only give negative effect as the percentage difference for sample D (PVC with 35% silica) is the highest for all the value tested.

5.2

Recommendation

For further study of this project, there are some recommendations that have been suggested. Other percentage of silica filler should also be studied to know the exact percentage of silica filler that we can use to have optimum performance of insulator. Furthermore, other tests for accelerated ageing test of polymeric material should be considered so that the true performance of polymeric material insulations after ageing could be predicted.

The tests are ultraviolet exposure test, corona

cutting test, and oxidative stability test.

37

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APPENDIX A

British Standard EN 62039:2007/IEC 62039:2007

41

42

43

44

45

46

47

48

49

50

51

52

53

54

APPENDIX B

British Standard EN 60587:2007

55

56

57

58

59

60

61

62

63

64

65

66

67

68

69