Corona Findings on Coated Insulators
Insulators coatings are used to retain their hydrophobic properties and extend their lifetime. Coating is usually performed every few years. There are several factors to consider before coating an insulator in order to reduce costs and time spending; first you should inspect your insulators for corona before coating so you coat only necessary components. Also, old coating needs to be removed due to physical deterioration of the coating material and the insulator's surface must be clean and smooth before a new coating.
Since coating cannot avoid corona discharges at all times, for example, coating needs to be perfectly applied since any small dry droplet can change the E-Field distribution leading to corona formation, therefore it is highly recommended to inspect for corona also after coating to ensure effectiveness. Corona, once started, will damage the coating present even if recently applied. It is known that cracks and air gaps can be sealed with coating material but small cracks may remain leading to corona formation. This can be avoided by inspecting for corona after coating.
The quality of the coating material is an important factor as well; choosing a high quality coating material can reduce damage to the insulator and avoid a quick peel-off that may lead to corona.
Following the above tips can avoid unplanned outages and reduce maintenance costs buy coat only necessary components and save on human resources. It can also, optimize equipment operational life creating a safe working environment.
Coating is an effective method to extend insulator's lifetime and DayCor® technology is the best way to ensure it does.