POWERSIL® 555 R
POWERSIL® 555 R Dispersion Coating is a one component liquid silicone RTV system that is designed as an insulator coating for high voltage applications. When exposed to moisture in the air, POWERSIL® 555 R cures to a flexible elastomer with excellent electrical and mechanical properties.
- Excellent unprimed adhesion
- Excellent unprimed adhesion
- One component, ready-to-use
- Easy to apply
- Sprayable or paintable
Protective coating for glass, porcelain or epoxy insulators and other high-voltage insulations, where contamination causes service problems. POWERSIL® 555 R prevents the formation of wet conductive films and therefore the risk of tracking and especially flashovers.
The surface to be coated should be clean and free of dust and grease. For cleaning of the insulator surface we suggest following operations: a) If the insulator was greased, different solvents (see below) are suitable to remove the grease. b) If the insulator surface shows adhering pollution like cement or other mineral or chemical pollutant cleaning by "corn cob" or carbondioxide blasting is recommended. c) In most other cases cleaning with water is sufficient. Following the above, the residual contaminants should be removed by thoroughly wiping with a cloth dipped in solvent and removal with clean cloth. Recommended solvents are hydrocarbon (fast drying ones, e.g. Shell X 55, slower drying ones, e. g. White Spirit or Mineral Turps) and Aromatic solvents (e. g. Toluene) and Chemical solvents (e. g. Acetone or Methyl Ethyl Ketone). Finish the cleaning just before spraying POWERSIL® 555 R with Isopropanol or an equivalent alcohol. In most cases it is not necessary to apply a primer before coating. Check carefully that there is no trace of dirt or grease left before spaying!
Insulators are coated preferably by spraying, but POWERSIL® 555 R can be applied by a brush (e.g. for repair) as well. For spraying application, the airless process has proved to be successful with following spraying equipment: - Airless gun: 200 bar - Flat nozzle: 0.33 mm, 20° - Air drive pump output: 150 bar - Setting of pressure output: 50 - 150 bar As a rule the spray gun should be moved evenly across the surface at a distance of about 50 cm. Due to the thixotropic properties of POWERSIL® 555 R it is usually possible to apply the first layer with a good cover. The second layer can be applied after approximately 30 minutes. With two coats, usually a dry film thickness of at least 0.5 mm (20 mils) will be achieved meaning a high protection for many years. Full cure is obtained within 8 - 12 hours depending on thickness and humidity. To reduce overspray it is important to keep the gun always in the direction of the insulator. The overspray should be limited not only because of cost reduction reasons but also to minimize the contamination of nearby devices. Wind during spraying will cause additional overspray and rain can damage the coating so try to protect job site or stop application! On basis of 70 % solids content we anticipate a requirement of approx. 1 kg of POWERSIL® 555 R to coat each square meter of porcelain insulator with a dry film thickness of 0.5 mm. We would suggest that an additional amount of approximately 10 % has to be calculated to take overspray into consideration. All spraying equipment should be cleaned with a nonpolar solvent (e. g. Xylene or White Spirit) immediately after use to avoid curing in the equipment.