Room Temperature Vulcanisation (RTV) silicone materials have been conceived as a remedial measure to mitigate pollution-related flashovers of #insulators suffering poor service performance. The RTV coating can be used in order to improve and protect the surface condition of a polymer insulator. This helps to improve the performance of the polymer insulator and increase its lifespan and #powersystem reliability.

1. Si-COAT® 570™ / 570hs™
RTV Silicone HVIC
WELCOME TO THE TECHNICAL
PRESENTATION OF RTV SILICONE HIGH
VOLTAGE INSULATOR COATING (HVIC)

2. CSL Silicones Inc, Canada
• CSL Silicones Inc. Canada is an ISO 9001
certified Primary Silicone Producer and a
Manufacturer of Room Temperature
Vulcanizing (RTV) Silicone High Voltage
Insulator Coatings and Anti- Corrosion
Protective Coatings.
• With 30 years of experience in the manufacture
of RTV Silicone products, we exceed the
highest Standards for Quality.
• Our coatings are giving satisfactory
performance in extreme service conditions for
more than 20 years.

3. CSL Silicones Inc. Canada

4. RTV HVIC Coating – A proven
solution for insulator pollution

5. Insulator Fundamentals
• Insulators are one of the vital components in the power
system network
• Insulators account for 3 to 8 % of investment costs in a
network – more for transmission and less for substation
• Insulator provides
– Mechanical support
– Electrical isolation
– Protection to critical equipments
• Effectiveness of insulator to perform the above
functions depends on material, proper design,
selection of insulator as well as associated equipments
– (for eg- corona ring) and changes in environmental
factors over a period of time

7. Contaminant & Source of Pollution
Contaminant Source of Pollution
Salt Coastal areas, Salt Industries
High ways with deposit of snow where salt is used
to melt the snow
Cement Cement Plant Construction sites Rock quarries
Fertilizers Fertilizer plants
Frequent use of fertilizers in cultivated fields
Coal Coal mining, Thermal Power Plants, Brick Kilns, Coal
Ash Handling Plants
Chemical Wide variety of Chemical / Process & Oil Industries
Smog Urban Pollution, Auto Emissions, Railway Engines
Birds & Animals Bird / Animal Droppings
Fog & Smoke Burning of Agri Waste, Wild Fires etc.
Mining Mining Industries, Earth Moving, Construction Sites

8. Criteria for Insulator Selection
• Type of Transmission – AC/DC
• System Voltage
• Mechanical Strength (Power
Transmission Capacity of the Line,
Conductor Used, cantilever and torsional
loads)
• Environmental pollution
• Location of the insulator in terms of
altitude, humidity conditions, etc.

9. • Used at all voltages (ac and dc transmission/substation)
• Used in excess of 150 years
• Line Insulator concepts are virtually unchanged since inception
and proven in demanding applications
• Methods exist to identify defective discs both on and off service
• Cap and pin design Modular construction, defects contained in a
unit, and does not propagate
• No concerns of aging – tracking/erosion, aging is very slow than
other installed equipment
• High degree of standardization obtained over long term
experience
• Adequately engineered to suite different levels of pollution
12
Porcelain Insulator – Inorganic Material

10. • Due to in-organic material composition these are not prone to
attack during storage and after installation
• Due to the established design, technology ceramic insulators are
in general preferred for high risk applications
• More uniform field distribution for porcelain and glass and less
prone to corona discharges
• Standard practices have been established due to the familiarity
of these insulators over hundreds of years as part of
maintenance inspection
• Inert to chemical attacks
13
Porcelain Insulator – Inorganic Material

11. Merits Principal Concerns
Ø Much has been
discussed in
various forums
Ø Behavior under non-standard pollutants to be
studied. (especially Indian conditions)
Ø Behavior under high NSDD levels to be
ascertained. (Flashover voltage reduces with
increased NSDD levels)
Ø Bird Pecking Issues
Ø Rodent attack at site on storage
Ø Biological growth on Insulators
Ø Power Arc Performance
Composite Insulator – Organic Material

12. 15
Difference Between Connecting Lengths

13. • No standards for live line working yet
• New manufacturers will experience new failure modes that are
unique. Will they participate in the learning process and share their
experience?
• Comfort level with users is higher at lower voltages – distribution class
compared to voltages in the range of 500 kV and above
• Multiple material formulations, designs, suppliers, many new &
unproven
• Methods to identify defective insulators online are still in their infancy
• Internal degradation is not visible, & cannot be identified from the
ground
• Performance is influenced by weather, birds, animals
• Low level of standardization currently compared to ceramics
Considering all these the usage of composites are restricted in
Thailand, Saudi Arabia and parts of US
• In recent lines in China, for tension applications, composites are
not being used
• In highly industrial areas like sugar cane and steel industry
locations composites is not preferred. 16
Concerns on Composite Insulators

14. 1)High long-term Humidity periods as it removes the good
hydrophobic surface properties of Composites.
2) Electrically conducting contamination (iron oxide, sugar
cane industry, etc.); as it cannot be washed off from a
composite Insulator.
3)Presence of Hygroscopic salt, including sea salt; as it
maintains liquid water solution on the surface that
destroys the surface properties.
4) Voltage level of application – As over 230 kV; the
electrical fields present accelerates the aging of
composite Insulators substantially
5) High altitude, including presence of ice; accelerates aging
and ice resistance is demonstrated to be low in composite
insulators.
17
Factors to be considered as risks when planning to use
Composite Insulators in Different Environments

15. Concern of Polymer Insulators: In Service

16. Photo: INMR Q2 2004 issue
Bird eaten Silicone insulators Brittle fracture of fibre rod
Concern of Polymer Insulators: In Service

17. Concern of Polymer Insulators: In Service

18. Concern of Polymer Insulators: In Service

19. Concern of Polymer Insulators: In Service

20. Concern of Polymer Insulators: In Service

21. Concern of Polymer Insulators: In Service

22. Concern of Polymer Insulators: In Service

23. Concern of Polymer Insulators: In Service

24. Photo: INMR Q2 2004 issue
Rat eaten Silicone insulators Biological growth on Silicone insulators
Concern of Polymer Insulators: In Storage

25. Summary – Porcelain / Polymer Insulator –
Pros & Cons
PORCELAIN INSULATORS COMPOSITE INSULATORS
Established Sources of Raw materials & Inspection
procedures
Low degree of Standardization for Raw materials – Core &
Housing
- Testing of Input Materials
- Testing of finished insulator
Established Technology & Standardized Practices Manufacturing process adopted by manufacturers is not
standardized.
- May lead to poor Interface Connections
- Brittle Fracture related issues.
Attacked by Birds/ Rodents/ Fungal Attack
- On line
- In Storage
Brittle Material. Susceptible to Moisture Ingress & consequent Brittle Fracture
Can be coated with RTV Silicone for better flashover
performance and is better than new composites
Hydrophobicity is destroyed by UV Radiation, Pollution ,high
humidity, corona Discharge etc.
Being Modular Construction, defect in a unit do not
propagate.
Prone to aging and leads to - Tracking , Erosion etc that
propagate along the length, permanent damage
Established methods available for detecting
defective units online.
No Established method for detecting defective insulator
available.
Regular washing will be effective in removing
contaminants
When regular washing is needed removing of insoluble
contamination not possible
Not enough Service Experience
28

26. Introduction of RTV HVIC Coatings
• The application of RTV Silicone High Voltage Insulator
Coatings to Porcelain, Glass, and Epoxy and in certain
cases even on Composite Insulators to increase their
performance under pollution is well accepted
maintenance technology in many utilities across the
world for both Substation & Transmission Line
Insulators since 1980’s.
• This technology is adopted for both existing and new
transmission lines and substations.
• It is also used on Epoxy / Polycrete insulators to
prevent moisture ingress in indoor and outdoor
applications.

27. Why there is a need for RTV HVIC
Coatings?
• There are many situations where substations or lines
are built in areas where the pollution exposure has
increased dramatically increased over the areas due to
rapid industrialization, steep increase in the vehicle
emission, heavy urbanization along with the vagaries
of nature such as moisture, dew and fog etc. apart from
the Salt Fog and Chemical Vapours.
• These situations can dramatically change the level of
pollution affecting the transmission line and substations
and there is a greater need to avert the risk of flash
overs to maintain grid reliability

28. Why there is a need for RTV HVIC
Coatings?
• Another major consideration is the increasing
cost of conventional cleaning of porcelain /
glass insulators and high cost of monitoring the
degradation of composite insulators. With fresh
water an increasingly expensive resource and
with labour costs of frequent washing from
truck or helicopter also going up, the relative
economic benefit of RTV Coatings versus
cleaning is growing

29. Why there is a need for RTV
Coatings?
• Yet another factor behind more and more utilities
opting for RTV is because it offers the electrical
benefits of silicone along with the mechanical integrity
of porcelain / glass insulators.
• Finally all utilities are not confident about the long term
performance of composite insulators in certain areas
where there is persistently high UV or where bird
pecking is a serious problem or in certain applications
such as tension strings.

30. What is the principle behind RTV
Coating?
• A thin layer of RTV Coating is applied by a spray
method on the surface of porcelain and glass
insulators which vastly increases their pollution
withstand capability since the silicone imparts ultra-
hydrophobicity to what otherwise be a hydrophilic
surface.
• Since the RTV Coatings contain rich concentration of
low molecular weight silicones (LMWS) chains that
continually migrate to the surface the insulator will
remain hydrophobic, even when covered by a layer of
pollution.

31. What is the principle behind RTV
Coating?
• The arc resistance filler to absorb the
heat during the dry band arcing used in
the RTV compound is also a very critical
component.
• It is recommended to go for RTV
compound with ATH (Alumina Tri
Hydrate) fillers for the effective service
life of RTV compound.

32. How long does the RTV HVIC
Coating remain effective?
• This is a very key question when comparing
the relative costs of RTV versus alternatives
such as Composites, Water washing or
Silicone grease.
• Much will depend on the quality of the coating
and the credentials of the RTV Coating
manufacturer and how well it has been
applied.
• Fortunately these variables are addressed
through a correct technical specification and
the IEEE Standard 1523 – 2002 for evaluation
of RTV Coatings.

33. How long does the RTV HVIC
Coating remain effective?
• Assuming the RTV Silicone Compound has
been manufactured and formulated by Primary
Silicone Producer and application is done by
trained personnel under controlled conditions,
it is reasonable to expect a service life of 20+
years or possibly even longer.
• For example the RTV Coating s applied in the
late 80’s and early 1990’s in many installations
are reportedly still in operation.

34. Do RTV HVIC Coatings ever need
to be cleaned?
• Generally no, although much will
depend on the type and rate of
pollution that accumulates on them
which is an exceptional event. High
pressure washing however should
be always avoided as this can
damage to the coating.

35. • RTV Silicon coating is applied to the Insulator surface by using a
special spray coating technique to completely eliminate
flashovers, leakage currents and surface discharges.
• The RTV Silicon coating provides an ultra-hydrophobic surface on
the porcelain / glass Insulators.
• It basically ensures that the contamination performance is superior
to composites because of the lower filler content and the lower
mean molecular weight of the RTV silicone.
• RTV coating can be adopted for both new and existing insulators.
• RTV coating provides a cost effective maintenance free option
ensuring no outage and no revenue loss due to shutdown.
• It basically leverages the mechanical integrity of ceramics / glass
and improves the surface performance to better level than
composite insulators.
38
RTV HVIC Coating - Summary

36. Best of both worlds,
mechanical strength
of porcelain/glass
and pollution
performance of
Composite
Insulators
– a proven solution for
pollution
RTV Silicon coating – Best of both
the Technologies

37. ØElimination of water washing
ØPrevention of pollution induced flashover
ØHydrophobicity recovery
ØExcellent adhesion
ØLong life – Estimated to be 20+ years
ØPresence of Arc Resistance Filler - Alumina Tri Hydrate
(ATH) to prevent dry band arcing.
Essential Qualities of RTV HVIC

38. Pollution from various sources (industrial, salt fog, fertilizer
dust, etc) contaminates the insulator surface.
The pollution combined with environmental moisture (rain,
fog, dew etc) creates an electrically conductive film on the
surface of the insulator.
The electrolytic film of water on the insulator’s surface
promotes Leakage Current.
An insulator experiencing leakage current is prone to
reduced reliability and requires regular maintenance.
Leakage current also represents a loss of electric power,
which is a financial loss.
Leakage current flowing across areas of lower diameter
generates heat due to the higher current density in this
area. Greater heat promotes the development of a “dry
band”.
Because the dry band creates a disruption in the voltage
profile across the insulator, small surface discharges
arise. This phenomenon is known as “dry band arcing’.
Science of RTV Coating

39. Coating the Insulator with Si-COAT HVIC eliminates
Leakage current.
The coating (grey) secretes a monolayer of LMWS
(green). LMWS can be thought of as an oil.
LMWS; very low surface energy +
very high dielectric strength
As contamination particles (black) come to rest on the
surface of the coating, they come in direct contact with
the microscopic LMWS.
Within a few minutes the contamination particles become
microencapsulated by the LMWS.
This is possible due to the very low surface energy
characteristic of the LMWS.
Excessive dry band arcing leads to corona discharge.
Effectively, an ionic gaseous plasma is created, which
surrounds the Insulator. The plasma is electrically
conductive.
The development of such plasma is the final step to
catastrophic failure in the form of a flashover.
Science of RTV Coating

40. The phonemenon described above provides very long term
protection. The long service life of Si-COAT has been
conclusively demonstrated on millions of insulators installed across
the globe since 1987.
Si-COAT affords such long term reliability due to its rich and dense
reserves of LMWS. Further, the unique and patented formula
ensures this LMWS migrates to the coating surface unimpeded.
Silicones intended for high voltage service must contain a critical
ingredient named ‘ATH”. Some low-quality products exclude the
ATH and replace it with very inexpensive quartz fillers. While
quartz-filled product is promoted as the latest generation of
technology, do not be fooled. ATH is essential. The Si-COAT HVIC
patent is based on the discovery that the optimum size of ATH is 13
microns.
Water (blue) that may collect on the surface is physically and
electrically isolated from the contamination particles. Electrical
isolation is by virtue of the very high dielectric strength of the
LMWS.
Further, the water forms in discrete droplets due to the very low
surface energy of the LMWS. This is known as hydrophobicity.
The elimination of water filiming further discourages leakage
current.
Science of RTV Coating

41. However, small ATH will clog the pathways within the
coating through which the LMWS must diffuse in order to
reach the coating surface.
LMWS must be allowed to freely & rapidly diffuse through
the body of the coating in order to quickly
microencapsulate contamination as it pollutes the
insulator surface.
Through deep research & testing it was determined by
the laboratories of CSL Silicones Inc, that the optimum
ATH particle size is 13 microns.
Si-COAT HVIC: The world’s best RTV Silicone HVIC
Patented Technology
The purpose of the ATH is to protect the silicone in case
surface discharges should occur under adverse
conditions. Without ATH, the silicone may burn.
Protection is provided by the surface of the ATH particle.
On a per unit mass basis, the surface area of ATH is
increased by making the particles smaller in size.
Science of RTV Coating

42. In most cases, Si-COAT achieves ultra-hydrophobity,
which is an extreme contact angle greater than 150o.
The abundance of LMWS in Si-COAT combined with
contamination particles creates a hydrophobic
microtexture on the surface of the coating. Science has
named this phenomenon the “Lotus Leaf Effect”. As on
a lotus leaf, water simply rolls away & vanishes.
Because Si-COAT HVIC develops ultra-hydrophobicity the
coating has a tendency to remain dry by quickly shedding off
water.
An insulator that remains dry is an insulator that remains at its
highest insulating performance.
Si-COAT HVIC is suitable for use on overhead transmission &
distribution lines and in substations.
Si-COAT is also suitable for use at all voltage levels including
the latest UHV projects.
Trust the science inside Si-COAT HVIC to solve your most
difficult insulation challenges.
An insulator freshly coated with Si-COAT HVIC
demonstrates excellent hydrophobicity.
The degree of hydrophobicity is measured by the contact
angle formed between a water droplet and the coating
surface.
In the case of fresh Si-COAT, a=120o on average.

43. RTV Silicone Coat LMWS encapsulates Dirt
(Si-COAT)
Silicone oil diffuses to the surface encapsulating the pollutant particle
within the LMWS layer.
Water prevented from coming into contact with the pollutant.
ATH absorbs energy of dry band arcs and prevents damage to
coating.
Science of RTV Coating

44. Water Can’t Combine with Dirt
Science of RTV Coating

45. RTV Coat (Si-COAT) Hydrophobicity
RTV Coating - Hydrophobicity

46. Silicon Coated Insulators exhibit a manifold increase in the withstand salinity level compared to uncoated
insulators.
– Pollution testing of coated and uncoated insulators prove it beyond doubt.
Artificial Pollution Test
Type
(400kV String
with 23 nos. of)
Withstand
Salinity
kg / m3
Uncoated
insulator
7
Si coat coated
insulator
160
RTV Coating – Test Reports

47. Hydrophobicity of coated insulators – The hydrophobicity of coated insulators in service is
almost equal to that of newly coated insulators.
RTV Coating – Test Reports

48. RTV Coating – Test Reports

49. RTV Coating – Test Reports

50. Installation Base : Si-COAT® 570™ in past 5 years
~80% of Si-COAT® HVIC
tonnage has been
implemented on OHTL in
past 3 years
Slide 53 of 23

51. RTV Coating – Proven Performance

52. RTV Coating – Proven Performance

53. RTV Coating – Proven Performance

54. RTV Coating – Proven Performance

55. RTV Coating – Proven Performance

56. RTV Coating – Proven Performance

57. RTV Coating – Proven Performance

58. RTV Coating – Proven Performance

59. RTV Coating – Proven Performance

60. RTV Coating – Proven Performance

61. Relative cost benefit: Water washing vs. Grease coating vs. Si Coat
RTV Coating – A Practical and
Viable Solution

62. Carbon Conscious
CO2 Offset
30 million kg / year *
Equivalent trees
1.4 million additional trees
* Per 1000km of a 245kV exposed line @ 2mA average leakage current
RTV Coating – Protection Against
Climate Change

63. Standards for RTV HVIC Coating
STANDARDS DESCRIPTION
IEE-1523-2018
IEEE Guide for the Application,
Maintenance, and Evaluation of Room
Temperature Vulcanizing (RTV)
Silicone Rubber Coating for Outdoor
Ceramic Insulator
Various important aspects that are
needed for satisfactory long-term
performance of High-Voltage Insulator
Coatings (HVIC) are presented in this
guide. Various possible application
scenarios, maintenance issues on
coated insulators, factors affecting
long-term performance, the question
of aging, laboratory accelerated tests,
and functional outdoor evaluation are
described.

64. Critical Tests for RTV HVIC Coating
Name of Tests Test Lab
Artificial Pollution Test CPRI, Bangalore
Hydrophobicity recovery by Corona
test
CPRI, Bangalore
Inclined Plane Tracking & Erosion Test POWERTECH, Canada
Test of Housing : Tracking and Erosion
Test
KEMA High Voltage Laboratory,
Netherlands
5000 hours Ageing test under
operating voltage simulating weather
condition
KEMA High Voltage Laboratory,
Netherlands

65. Application Photos

66. © 2012 CSL Silicones Inc. All trademarks registered. All rights reserved.
Coating Application at Site with
Manual Process

67. © 2012 CSL Silicones Inc. All trademarks registered. All rights reserved.
Coating Application at Site with
Manual Process

68. © 2012 CSL Silicones Inc. All trademarks registered. All rights reserved.
Coating Application at Site with
Manual Process

69. © 2012 CSL Silicones Inc. All trademarks registered. All rights reserved.
Coating Application at Site with
Manual Process

70. © 2012 CSL Silicones Inc. All trademarks registered. All rights reserved.
Coating Application at Site with
Manual Process

71. Application Photos

72. Application Photos

73. Application Photos

74. Application Photos

75. Application Photos

76. Application Photos

77. Application Photos

78. Application Photos

79. Application Photos

80. Application Photos

81. Application Photos

82. Application Photos

83. © 2012 CSL Silicones Inc. All trademarks registered. All rights reserved.
Equipment for Application
§ With a 120 cc
Honda engine and
additional features
for increased
productivity, the
GMAX II 3900 can
handle up to two
guns and is ideal
for the professional
RTV coating
application
contractor.
We recommend GRACO Airless Spray Pump for Application of RTV
Silicone Coating

84. © 2012 CSL Silicones Inc. All trademarks registered. All rights reserved.
Equipment for Application
• With a 160 cc Honda engine and the ability to spray up to
1.6 gallons per minute, the GMAX II 5900 is the industry
standard for the professional RTV coating application
contractors.
We recommend GRACO Airless Spray Pump for Application of RTV
Silicone Coating

85. RTV Silicone HVIC
Thanks
10/23/20
Q & A Session