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Questions
Answers
How does Si-COAT 570 HVIC stop leakage current
leading to flashover?
Leakage current is caused by contaminants such as salt, sand,
carbon, fly ash, etc. settling on the surface of an insulator.
When these contaminants are combined with natural mositure
(rain, fog, dew, etc.) current leaks down the body of the
insulator. If the flow of current is too great, the electricity
in the conductor will take the shortest path to ground, which
is across the full length of the insulator and down the tower
or pole. This is called a flashover. Flashovers result in
expensive power outages and repair costs.Si-COAT 570 HVIC's
patented formulation stops leakage current by virtue of the
non-conductive free fluid present in the cured coating. After
the coating has been applied to the insulator surface, the
free fluid migrates to the surface of the coating to form
a one molecule thick layer. This layer is referred to as the
"monolayer" and forms naturally due to the low surface tension
property of the fluid.As contaminants settle of the surface
of the coated insulator, they come in contact with the free
fluid. Again, because of the low surface tension of the free
fluid, it automatically encapsulates the contaminant particle,
creating a non-conductive envelope. Thus, current cannot find
a conductive path to follow down the insulator body and is
effectively suppressed.Natural moisture in the form of rain,
fog, dew, etc. bead up into tiny water droplets when in contact
with the free fluid. Again, this is due to the low surface
tension of the fluid. When enough moisture has accumulated
on the surface, it will wash the encapsulated contaminants
and the monolayer of free fluid away. When the monolayer has
been washed away, it immediately regenerates to once again
protect the insulator from leakage current.
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How long will Si-COAT 570 last?
The life of Si-COAT 570 HVIC depends greatly upon its service
conditions. Field applications have been in place up to 18
years without any failure. A minimum five years of service
life can be expected from Si-COAT 570, however.Laboratory
tests indicate that Si-COAT 570 HVIC will last greater than
30 years. As a caveat, this projection has yet to be verified
by field experience.
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Can I use Si-COAT 570 HVIC on my polymer/composite
insulators?
Yes. Si-COAT 570 HVIC adheres just as strongly to polymer/composite
(heat cure silicone, LSR, EPDM, etc.) insulators as it does
to porcelain and glass insulators. Si-COAT 570 HVIC can be
used to enhance the hydrophobicity and leakage current prevention
properties of polymer insulators.
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Does Si-COAT offer turnkey applications
of Si-COAT 570 HVIC?
Yes. The experts at Si-COAT can offer you a turnkey solution
to your needs for insulator coating in most places around
the world. Please contact CSL Silicones Inc. for more information.
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Is water washing necessary after I use Si-COAT
570 HVIC?
In most cases water washing of Si-COAT 570 HVIC is not necessary.
However, in extreme circumstances where pollution levels are
abnormally high or rainfall levels are abnormally low, water
washing may be necessary in order to keep Si-COAT 570 HVIC
performing optimally. The frequency of water washing will
depend on the exact circumstances of the application environment.
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Is the final dry film thickness of the coating
critical to its performance?
 An
average dry film thickness (DFT) of 15 to 20 mils (380 to
500 microns) of Si-COAT 570 HVIC is required for optimum product
performance. If the final DFT is greater than 15 to 20 mils
(380 to 500 microns), product performance is NOT reduced.
It should be noted, however, that a greater thickness of coating
will not lead directly to longer product life. Applying the
coating in excessive thickness is merely a waste of material.
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Si-COAT
570 Material Safety Data Sheet
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