A corona ring also called an anti-corona ring, it is a toroid-shaped metal ring that is attached to a terminal of high voltage equipment. For system voltages 230kV and above, a corona ring is necessary. The primary role of the corona ring is to reduce corona discharge using corona rings which occur in high-voltage power lines.

Made from copper, steel, and aluminum the corona ring is packed in wooden case and cartons, Corona discharge occurs when there is an excessive localized electric field gradient as the diameter of the ring is inversely proportional to the voltage percentage of the lowermost insulators.

Corona discharge occurs in high power discharge lines using corona rings which can help reduce the corona discharge because they can damage the insulators and may produce breakdown products. To suppress the corona discharge, the wire-to-ring current flow is being formed up instead of wire-to-air.

The hot end of the stack will have a far more voltage drop across the insulators because of the stack of insulators used for EHV insulation.

Accessories used with corona rings are:

400kv transmission line
Corona discharge
Surge arrester
Composite insulators
Grading rings

Can be used on extremely high voltage apparatus
Prolong the lifetime of insulator surfaces
Can easily be installed on the insulators of antennas of high-power radio transmitters
Increase the capacitance of the insulators


What is Corona Ring?

The basic purpose of the corona ring is to distribute an electric field gradient by lowering the corona threshold. Corona rings produce high voltages because of high voltage power transmission insulators and switchgear.

How is the Corona Ring used?

Corona ring and combination of corona rings are necessary above 230kv while high altitude, high contamination, and tight phase spacing may require rings at lower system voltages.

What is the function of the Corona Ring?

The smooth, large diameter of spherical corona toroids controls the electric field by suppressing the generation of the corona. The diameter of corona balls must increase to obtain corona suppression.

How do you install Corona Ring?
  • I string – gap should be above the conductors.
  • Dead end – to face them each other, orient the gap inside
  • V-strings- put the gaps inside of the V by facing each other
  • Line posts- by pointing the gap downwards plant the corona rings there
  • Braced line posts fix the corona rings down on the suspension with the gap pointing downwards
What are the types of products used with Corona Rings?

There is a certain type of product used with corona rings i.e.There is a certain type of product used with corona rings i.e.

  • Corona discharge
  • Electrical power
  • Insulators
  • Transmission lines
  • Guard ring
  • Voltage measurements
  • Grading ring

Corona Ring Drawing

Configuration-1 Configuration-2 Configuration-3
Shed diameter D1/D2/D3 (mm) 171/85 190/131/100 145/110
Shed spacing B (mm) 79 79 60
Leakage path distance L (mm) 13270 16300 13370
Width of end fittings W (mm) 72.4 72.4 86.6
Corona ring diameter D (mm) 370
Corona tube diameter d (mm) 50
Corona ring position H (mm) 110