Corona Ring Information Sheet

High voltages can result in unwanted noise (RIV) and corona. To minimize the effects of corona, corona rings are applied to one or both ends of the insulator (attached onto the end fittings). Typically, for system voltages 230kV and above a corona ring or combination of rings is necessary. However, some applications may require rings at lower system voltages when addition corona protection is required; high contamination, high altitude, or applications with tight phase spacing. For these special cases or any corona ring application assistance, contact MPS.

The MPS Smart Fit corona rings are designed around the needs of the end user. It is easy to install, unidirectional (not able to install in the wrong direction), and can be installed or removed with hot stick tools. By making the ring a one-piece design, we have eliminated the problem of missing or lost parts. This was made possible by designing a unique clamping mechanism that uses two bolted keepers to secure the ring to the insulator. Additionally, the clamping section was designed such that the ring can only be installed in one direction, which eliminates the problem of misapplied rings. As a final step, the ring was designed with a split (opening) to allow installation with hot stick tools.

Recommended Corona Ring Application Table
138 kV 161 kV 230 kV 345 kV 400 kV 500 kV
Line End None None 8” 12” 12” 17’
Tower End None None None None 8” 8”

Three Ring Diameters are also available for use on all suspension insulator styles:


For insulators 230 kV and above, MPS recommends use of Corona Rings.  The application table above depicts typical corona ring usage on MPS suspension Insulators.  For corona ring usage on special applications, environments, and elevations, please contact MPS.
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