Design and application of corona and grading rings for composite insulators

The addition of a corona ring to a polymer insulator will improve the insulators performance, but it must be the right ring used for the right reasons to realize the benefits. A corona ring should not be a quick fix to a problem; it may only mask a bigger concern or delay the inevitable. Selection of a corona ring is as critical a decision as picking the appropriate dry arc, leakage, or mechanical rating for the insulator. Beyond selecting the appropriate size ring for a specific voltage, other critical characteristics include attachment type, mating feature, hot stick-able design, ordering, and packaging.