Si-COAT® 570™ Reliability &...

Si-COAT® 570™RTV Silicone HVIC

Reliability & Beyond

Seminar Presentation

© 2012 CSL Silicones Inc. All trademarks registered. All rights reserved.

Overview

• Background & industry pressures₋ Early validation of Si-COAT HVIC

• The science of Si-COAT

• Q&A


Si-COAT HVIC : The Background

• A need for a robust insulator coating₋ Excellent adhesion required

₋ Elimination of water washing required

• Si-COAT Formulated for:

₋ Superior adhesion

₋ Very smooth surface finish

₋ Extremely long life

• Two very surprising advantages discovered!


Si-COAT : The Advantages

• One-part RTV (ready-to-use)

• Superior adhesion

• Smooth surface finish

• Rich LMWS concentration

• Low surface free energy₋ Very high hydrophobicity

• Maintenance free

• Near total suppression of leakage current


A Thorn in Reliability’s Side…

Insulator contamination : a long posed nuisance

• Water washing

₋ Short-term solution

• Greasing

₋ Short-term solution

• Composite insulators

₋ Questionable reliability

• RTV Silicone Coatings

₋ Reliable performance

₋ Leverages mechanical integrity of ceramics

₋ A cure for ailing composites


0

50

100

150

200

250

Year 0 Year 2 Year 4 Year 6 Year 8 Year 10

Cum

ula

tive E

xpen

se

Water

Grease

Si-COAT

Si-COAT versus Water & Grease


Si-COAT : a Remarkable Effect

Leakage current nearly eradicatedLABORATORY

• Zittau University (Germany) Testing₋ IEC 62217 Salt Fog Test; 1,000 hours

• KEMA (Netherlands) Testing₋ IEC 61109 Salt Fog Test; 5,000 hours

FIELD

• US Dept. of Energy₋ > 99% suppression over 10 years

• PPC Greece₋ > 99.9% suppression in IEC Class IV contamination zone

• Kinectrics Research₋ 20 kW/km recoverable!

• Koeberg (KIPTS) Testing


IEC 62217 : 1,000 hr Si-COAT Result

Data : Prof R. Bärsch, HV Lab, Zittau University of Applied Sciences

Test Parameters• Medium voltage porcelain

- 700 mm creepage

- 60 mm core diameter

- 122 mm shed diameter

- 355 mm dry arc resistance

• 20.3 kV ; 0.29 kV/cm

• 6.7 mS/cm fog conductivity (ref. 50 mS/cm for sea water)

Observation• Max leakage current of

<0.1 mA


IEC 61109 : Si-COAT Shines

Final Test Report, KEMA Laboratories, The Netherlands, 2004


Si-COAT ® HVIC Thermal Imagingin Rural Italy

Thermal imaging via infrared cameras measures the rise in temperature, above ambient, of various structures.

Since leakage current generates heat, thermal imaging is an ideal and cost-efficient tool to measure approximate levels of leakage current.

Thermal imaging by infrared cameras of insulators coated withSi-COAT and those left uncoated reveal that uncoated insulators undergo an appreciable rise in temperature.

Each Celsius degree rise in temperature above ambient roughly correlates to 2 mA of leakage current.

The approximate 9°C temperature rise of uncoated sections in this photograph indicate roughly 18 mA of leakage current on uncoated insulators.

Coated insulators show no rise in temperature, translating to an effective zero level of leakage current.

Si-COAT HVIC coated insulator

(at ambient temp.)

Uncoated insulators

(at elevated temp.)

Photo courtesy of Terna of the Enel Group, Italy


US Dept. of Energy Experience

Columbia Generating Station

• 1,150 MW Nuclear Plant

• Owned & operated by Energy Northwest

• Sole customer is Bonneville Power Administration (US Dept. of Energy)

• East side of Washington State₋ Seemingly unlikely place

for insulator contamination


(US DoE) : Plant Configuration


(US DoE) : Plant Configuration

Transformer yard on north side of station


• Prevailing winds from south

• Plume & contaminants carried to transformer yard

northsouth

(US DoE) : Contamination Issues



Condensed plume migrating north to transformer yard



Typical contamination buildup



• Cooling water drawn from Columbia River

• Contamination sources₋ Natural river contaminants

₋ Buffer chemicals

• Contaminants in circulation water₋ Anions:

sulphate, bicarbonate, silica, chloride, orthophosphate, fluoride

₋ Cations:calcium, magnesium, sodium, ammonia, copper, zinc, iron


(US DoE) : Failure in Reliability

Flashover #1:

• 17h14, 30-January-89

• Plume condensed in cold

• Corrective action: annual water washing

Flashover #2:

• 10h10, 10-December-90

• Corrective action: find the correct solution


I. Cleaning• Off-line cleaning• Hot line washing• Installed insulator washers

II. Monitoring• Insulator leakage current

monitoring• Weekly measurement of ESDD• Meteorological monitoring• RF/Ultrasonic

III. Contamination Source Reduction• Transformer Yard cover• Transformer Yard wind

deflectors• Drift eliminators• Cooling tower plume reduction• Hot air ducted into transformer

yard

IV. Insulator Modifications• Fog type insulators• Non-ceramic insulators• Resistance graded insulators• Creepage extenders• Silicone grease• Si-COAT RTV Silicone HVIC

(US DoE) : Reliability Investigations


(US DoE) : Si-COAT HVIC Testing

• Si-COAT under test from 1989

• Intensive testing initiated late 1991

• Principal property was to improve hydrophobicity (prevent water filming)


Fog Chamber Tests Round 1 (31-Dec-92)

• Coated & uncoated insulators first contaminated for 3 months under plume

• ESDD up to 0.111 mg/cm2, area weighted avg.

Trial #1 Trial #2

Minutes to Flashover

Per Unit Rated Voltage

Minutes to Flashover


Bare 20 2.0 55 2.0

Other RTV 94 2.0 116 2.0

Si-COAT RTV >120 2.6 >120 2.9



Fog Chamber Tests Round 2 (05-May-93)

• 31.5 in station post insulators

• Exposure:₋ 20 days tower mist and 26 lbs dust

₋ 5 days mist and heat cyclingFlashover Voltage


Bare 117 kV 1.52

Company 1 RTV 131 kV 1.70

Company 2 RTV 227 kV 2.94

Silicone Grease A 240 kV 3.11

CSL-880 Grease 250 kV 3.25

Si-COAT RTV 251 kV 3.26



(US DoE) : Conclusions

• Si-COAT provided superior results for reducing risk and preventing flashover

• With the concurrence of US DoE, Energy Northwest determined Si-COAT (CSL) RTV HVIC offered best prospects for preventing future service interruptions


(US DoE) : Results

• Si-COAT virtually eliminated leakage current

Maximum Broad-Band Leakage Current

Uncoated Insulator

Si-COAT RTV HVIC Coated Insulator

18-Dec-93 50 mA< 0.25 mA(> 99.5%

suppression)

Apr-94 100 mA< 0.25 mA(> 99.8%

suppression)


(US DoE) : Results

• US DoE Internal Report 03-Jun-94₋ Si-COAT avoided at least 6 forced outages in first

year alone

• Leakage current, hydrophobicity and resistance testing indicated good condition after 10 years of service₋ Recoat at 10 years as insurance

• Few visible signs of degradation


The Science


electrons LEAKalong a dirty insulator

particlesof dirt

Insulators conditions are not Perfect


How Does Si-COAT Work?


Si-COAT LMWS Encapsulates Dirt


Water Can’t Combine with Dirt


Si-COAT has Most LMWS

Si-COAT Other RTV HVIC

Relative bulk LMWS concentrations as revealed by X-ray mapping technique


How To Avoid Damage to Silicone!

this area getsWARM & DRY


• Dry band arcing₋ Very high

temperatures

₋ Can damage unprotected coating

How To Avoid Damage to Silicone!


Dry Band Arcing Damage is Beaten

• ATH: Alumina Trihydrate

• Dry band arcing activates ATH

• ATH absorbs the energy of dry band arcing

• Coating is protected and undamaged

• Surface of ATH particle is most critical

₋ The greater the surface area of the ATH, the more protection that is offered


Smaller ATH = More Surface Area


Very Small ATH Restricts LMWS


Larger ATH Promotes LMWS Flow


13 microns : Optimum ATH Size

• The basis of CSL’s patent for Si-COAT HVIC is the 13 micron Optimum ATH Particle Size


Developing Ultra-Hydrophobicity


Ultra-Hydrophobicity Explained

• Ultra-Hydrophobicity is also known as “The Lotus Leaf Effect”


Ultra-Hydrophobicity Explained


Ultra-Hydrophobicity, Turkey (2 years)






In Conclusion

1. The Si-COAT patented technology proposes three levels of value:

• Maintenance reduction

• Reliability improvement

• Economic/Environmental benefits

2. Si-COAT virtually eliminates leakage current for the long term

3. Therefore, significant reduction in expenses and losses due to planned/unplanned outages

4. Investment in Si-COAT veryquickly recovered


Q&A Session

Seminar Presentation

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