As young apprentice electrical/electronic engineer I was always impressed when seeing high voltage electrical equipment. An aura surrounded the equipment. There was a distinct odour when in the presence of such equipment, which may have been accountable to the shellac used as a protective coating. The equipment created visions seen in  sci-fi films and TV programs, where spheres and sparks were intended to create a scene of technology advance and a sinister environment. Hmmmm???

So what are the large ‘donut rings’, toroid’s or whatever, commonly associated with high voltage transmission systems? Well the correct name is a corona ring, and is sometimes referred to as anti-corona ring.

A corona ringis a toroid of conductive material, usually metal and most often aluminium, which is attached to a terminal or other irregular shaped piece of high voltage equipment.

The purpose of a corona ring is to aid even distribution of the ’electric field’ which accumulates at a connection point in the high voltage system. The corona ring reduces the ‘peaks’ of the electrical field which would form at ‘jagged/pointed’ parts of the connection point. In doing so the corona ring reduces or distributes the magnitude of the electrical field over the surface of the corona ring to a value below the corona threshold.

This prevents the occurrence of a natural phenomenon referred to as corona discharge (first stages of electrical arcing) by transferring the destructive effect of the electrical field from the valuable high voltage hardware to the expendable corona ring.

Corona rings are very similar and related in operation to a grading ring, which is used and located around insulators on medium/high voltage power systems.

Eur Ing Dr Robert Brown (Robert) is a Consultant Engineer in the fields Electrical Electronic and Control Engineering. Robert is also an accomplished professional Expert Witness having prepared and presented many court compliant reports and presented oral evidence within the High Court, Crown Courts and County Courts.

For further information please contact Robert via;

Email,…robert.brown@frasergeorge.com   or   robertbrown@robertbrown.uk.com

Tel Land: +44 (0)1777 709175

Tel Mobile: +44 (0) 7976250624