Frodsham 2 circuit is at Fiddlers Ferry coal fired power station. These insulators are directly opposite the coal mound which is continually moved causing high levels of dust in the air. There is a constant build up of coal dust on the insulator surfaces which can be seen in the above photos.

The through wall bushings and VT’s were coated in hydrocarbon grease which had become completely saturated with coal dust and no longer providing protection.  

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A polluted surface causes the insulator to become hydrophilic which results in wetting during high levels of moisture or rainfall. This could cause arcing and tracking on the surface which would ultimately lead to flashover.

Access to the insulators was by Mobile Elevated Work Platforms.

The grease on the through wall bushings had become hardened to the underside of the skirts and was hard to remove. The grease had been baked on by sunlight and the profiles on the underside of the insulators were deep and very awkward to access. All surfaces of the insulators were thoroughly cleaned and absolutely all traces of hydrocarbon grease removed.

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Finally the insulators were coated with rtv silicone HVIC to a thickness of approximately 0.5mm. This will provide maintenance-free protection for an expected minimum of 10 years in this highly polluted environment. In 10 or more years time the insulators can be re-coated with rtv silicone. Surface contamination does not stick to the silicone surface so cleaning is relatively simple and a lot less time consuming!