The Science of Superhydrophobicity: Enhancing Outdoor Electrical Insulators

ABSTRACT

In present era, a world without electric current is unimaginable. Transportation of electric current from power source to home appliances entails more equipment like generators, transformers, overhead lines, power cables etc. This equipment generally operates at high-voltage ranging above 22 kV and more. Also, this equipment is predominantly responsible for reliable and uninterrupted power supply. Among all the astonishing equipment found in power transmission and distribution networks, the insulator plays a vital role by providing mechanical support and electrical protection to power system. Despite all these noteworthy facts, the breakdown of insulators owing to surface contaminants appears to be particularly fascinating in today's scientific world. Researchers provide a plethora of methods to eradicate this problem.

In order to alleviate these failure mechanisms, research thorough knowledge about the same is essential. This plethora of texts aims in serving this purpose. A field study has been carried out in the nearby utilitarian

sub-station to explore the operations and practical difficulties of high-voltage outdoor insulators. Field observations of the same has been inscribed into descriptive information. Hereby, this research surveys different types of outdoor insulation materials exploited in different high-voltage equipment. Besides, proposed method details failure mechanisms prevailing in different insulating material. Conclusively, this study illustrates the methods to prevent the insulation breakdown mechanisms with the objective of providing insightful subject matter to the upcoming researchers of this field.

Amidst the methods, superhydrophobic coating for insulators which is one of the widely used method, provide better solution as it offers resistance to moisture, wetness, dust and ice. This unique property of superhydrophobic coated insulators require further investigation. Hence to achieve this purpose, by preparing a superhydrophobic solution with PDMS (Polydimethylsiloxane) chemical and preparation of superhydrophobic solution of PDMS (Poly di methyl siloxane) with MTMS (Methyl tri methoxy silane) composites was made and comparative analyze was performed. In this study superhydrophobic coatings were prepared by using sol-gel method and spray coating technique. Characterization studies were performed by using goniometer to measure the Contact Angle (CA) for superhydrophobic coating on insulator surface and it was found to be from 165° to 170° and sliding angle was from 5° to 10° confirming superhydrophobic property. Fourier Transforms Infrared Spectroscopy (FTIR) analysis validates the chemical composite of the coatings. Surface roughness and surface energy for this coating are also analyzed. UV spectroscopy analysis was conducted to determine transmittance values of PDMS and PDMS/MTMS coatings. Scanning Electron Microscope (SEM) analysis was used to observe the surface morphology of coating with estimated thickness L=2μm. Thermogravimetric analysis (TGA) was conducted to study about thermal withstanding limit of the coating above 600°C. Simulation model for studying flashover occurrence, adhesion property of water was built using COMSOL Multiphysics Software. Megger insulation test is conducted in an intentional contaminated conditions based on solid layer method of IEC60507 standards and IEC 60587 standards insulation resistances were tested using a megger instrument and self-cleaning ability of coating was also determined in this research. Mechanical durability and stability of superhydrophobic coatings test (adhesive tape peeling, sand paper abrasion, sand impact and pencil hard test) have been conducted in this research to determine superhydrophobic property. Even though there are countable contributions in this theme, this work stands out of the ordinary owing to the real-time field study that has not been performed so far in the existing literatures for this theme.

ACKNOWLEDGEMENT

Thankfulness is the beginning of gratitude. Gratitude is the completion of thankfulness - Henri Frederic Amiel.

God will make a way when there seems to be no way - Thank you God

First and foremost, I humbly bow down before God Almighty for giving me the opportunities to cultivate patience, tolerance, hope in my life and in completing the research work successfully. If all the world could have your dedication, there would be more progress and more interest in education. Thank you for showing resilience in it all. This research work and ebook would have not been possible without the support and scrupulous guidance of Dr. N. Jaya, Associate Professor, Department of Petrochemical Technology, University college of Engineering, BIT Campus, Anna university, Trichy. I feel extremely privileged and blessed to work under her supervision. The way she taught, the love she showered, the knowledge she imparted, the care she took, made her the best mentor and I must acknowledge all the efforts she put to lift me up in life and research. Her inspirations, deep rooted positivity, freedom to practicalize the ideas were central features in successful completion of this research work.

I wholeheartedly thank Dr.S.Venkatesan, Professor and Head, Department of Petrochemical Technology, University college of Engineering, BIT Campus, Anna university, Trichy for his sustained encouragement towards research development.

I wish my sincere thanks to my DC members Dr.R. Kanimozhi, Associate Professor, Department of Electrical & Electronics Engineering, University college of Engineering, BIT Campus, Anna University, Trichy and Dr.C. Naveen Kumar, Principal scientist, Department of Electroplating and Metal finishing, CSIR-Central Electrochemical Research Institute, Karaikudi, for their comments and suggestions during periodic doctoral committee meetings.

No love is greater than mom’s love and no care is greater than dad’s care. I am very much grateful to my mother Mrs.T. Josephine Clara Marry and my father Mr.K. Kanagaraj and my sister Mrs.K. Abirami for their belief, generous blessings and support throughout my life. Without their inspiration, drive, I might not be the person I am today, I am very much thankful for their immense support in doing the research work. I personally thank all my friends and relatives for being pillars of support at my hard times and celebrating me for every small thing. Gratitude unlocks the fullness of life. I am grateful to everyone for all who have been my amiable support.

INDIRAJITH K

TABLE OF CONTENTS

CHAPTER NO.   TITLE     PAGE NO.

ABSTRACT       iii

LIST OF TABLES   xi

LIST OF FIGURES     xii

LIST OF  ABBREVIATIONS xvii

1 INTRODUCTION   1

1.1  OVERVIEW OF AN INSULATOR IN

POWER SYSTEM  1

1.1.1 Problem Statement and Background 1

1.1.2 Surfaces: Hydrophilic, Hydrophobic

& Superhydrophobic Surface 2

1.1.2.1 Hydrophilic surfaces 5

1.1.2.2 Hydrophobic surface 6

1.1.2.3 Super-hydrophobic surface 8

1.1.3 Van der Waals Force 9

1.1.4 Electrostatic Forces 10

1.1.5 Wettability Properties and its Theory 10

1.1.6 Coating Technology 11

1.1.7 Thin Film Technique 11

1.2 OBJECTIVES OF THE RESEARCH WORK 13

1.3 ORGANIZATION OF EBOOK 14

2 LITERATURE REVIEW- INSULATOR

PROTECTIVE COATINGS AND APPLICATIONS 17

CHAPTER NO.   TITLE     PAGE NO.

3 MATERIALS AND METHODS USED TO

FABRICATE SUPERHYDROPHOBIC COATINGS 51

3.1 INTRODUCTION  51

3.2 MATERIALS SELECTION 51

3.2.1 Clay   52

3.2.2 Feldspar   53

3.2.3 Silica   53

3.3 PORCELAIN MANUFACTURING

PROCESS    53

3.3.1 Moulding of Raw Material 54

3.3.2 Cleaning and Mixing 54

3.3.3 Making of Porcelain Material Body 54

3.3.4 Glazing   55

3.3.5 Firing   56

3.4 MATERIALS USED FOR SYNEBOOK  

OF SUPERHYDROPHOBIC COATING 56

3.4.1 Poly Di Methyl Siloxane (PDMS) 59

3.4.2 Silanes   62

3.4.2.1 Tetra Ethyl Ortho

Silicate (TEOS) 63

3.4.2.2 Methyl Tri Methoxy

Silane (MTMS) 64

3.4.2.3 (3-Aminopropyl) Tri Ethoxy

Silane (APTES) 66

3.5 DEPOSITION TECHNIQUES 67

3.5.1 Techniques Employed in this Study 68

3.5.1.1 Sol-gel method 68

3.5.1.2 Spray coating technique 70

CHAPTER NO.   TITLE     PAGE NO.

3.6 PREPARATION OF SUPERHYDROPHOBIC

COATING BASED ON SOL-GEL AND

SPRAY COATING TECHNIQUE 71

3.6.1 Sample 1 (PDMS) 71

3.6.2 Sample 2 (PDMS/MTMS) 71

3.7 THIN FILM PREPARATION 72

3.8 CHARACTERIZATION   73

4 CHARACTERIZATION OF PDMS AND

PDMS/MTMS SUPERHYDROPHOBIC

COATINGS     74

4.1 INTRODUCTION  74

4.2 CHARACTERIZATION TECHNIQUE 74

4.2.1 Thickness   75

4.2.2 Contact Angle (CA)  75

4.2.3 Surface Roughness and Surface Energy 76

4.2.4 UV-Visible Spectroscopy 77

4.2.5 Fourier Transform Infra-Red

Spectroscopy (FTIR) 78

4.2.6 Scanning Electron Microscopic

Analysis (SEM)   79

4.2.7 Thermogravimetric Analysis (TGA) 80

4.3 OUTDOOR INSULATOR TEST 80

4.3.1 Megger Insulation Test 80

4.4 MECHANICAL DURABILITY AND

STABILITY OF SUPERHYDROPHOBIC  

COATINGS   81

CHAPTER NO.   TITLE     PAGE NO.

4.4.1 Stability against Adhesive

Tape Peeling Test 81

4.4.2 Durability against Abrasion

(Sandpaper, Sand Impact, and

Pencil Hardness Test) 82

4.5 COMSOL MULTIPHYSICS

SIMULATION SOFTWARE   83

4.5.1 Navier-Stokes equations   84

5 CHARACTERIZATION AND ANALYSIS

OF COATINGS FOR PORCELAIN

INSULATOR     89

5.1 THICKNESS

5.2  CONTACT ANGLE- SAMPLE 1

(PDMS)      89

5.3 SURFACE ROUGHNESS AND

SURFACE ENERGY  90

5.4 UV-VISIBLE SPECTROSCOPY 92

5.5 FOURIER TRANSFORMS

INFRARED SPECTROSCOPY (FTIR)     93

5.6 SCANNING ELECTRON MICROSCOPIC

ANALYSIS - SAMPLE 1 (PDMS) 94

5.7 CONTACT ANGLE- SAMPLE 2

(PDMS/MTMS)   95

5.8  SCANNING ELECTRON MICROSCOPIC

ANALYSIS - SAMPLE 2 (PDMS/MTMS)   97

5.9 THERMOGRAVIMETRIC ANALYSIS  

(TGA) RESULTS     98

CHAPTER NO.   TITLE     PAGE NO.

5.10 OUTDOOR INSULATION TEST    99

5.10.1 Megger Insulation Test  99

5.10.1.1 Line to earth test 

(Artificial salt contamination

test)  99

5.10.1.2 Line to line test

(Artificial dust pollution test) 102

5.11  SELF-CLEANING ABILITY   103

5.12 DEEP UNDERWATER STABILITY 104

5.13 MECHANICAL DURABILITY AND

STABILITY OF SUPERHYDROPHOBIC

COATINGS   105

5.13.1 Sandpaper Abrasion Test 105

5.13.2 Adhesive Tape Test 107

5.13.3 Pencil Hardness Test 108

5.14 SIMULATION ANALYSIS 108

5.14.1 COMSOL Simulation Analysis 108

6 COMPARATIVE STUDY OF PDMS

AND PDMS/MTMS SUPERHYDROPHOBIC

COATINGS     117

7 CONCLUSION    120

7.1 SUMMARY   120

7.2 FUTURE WORK  123

REFERENCES    124

LIST OF PUBLICATIONS  147

LIST OF TABLES

.   

LIST OF FIGURES