Wortai corona ring, also called an anti-corona ring, is a toroid of
conductive material, usually metal, which is attached to a terminal
or other irregular hardware piece of high voltage equipment. The
role of the corona ring is to distribute the electric field
gradient and lower its maximum values below the corona threshold,
either preventing corona discharge entirely or transferring its
destructive effects from the valuable hardware to the expendable
ring. Corona rings are used on very high voltage power transmission
insulators and switchgear, and on scientific research apparatus
that generates high voltages. A very similar related device, the
grading ring, is used around insulators.
