Partial discharge / corona discharge

[norske]

Hi everyone,

Is there a difference between corona and partial discharge or are the two terms interchangeable? Also is some one able to shed some light on how this phenomenon occurs.

Many thanks to all who answer in advance

Regards

Norske

 

[alehman]

Corona is a partial discharge in air. It occurs when the insulating material begins to ionize or conduct due to voltage stress. In solid materials, partial discharge penetrates and chemically breaks down the insulation.

See

http://www.eatonelectrical.com/NASA...ink&c=Apubarticles&cid=1035391670096&Sec=home

 

[nostrayvoltage]

I think the reality is that most people use the two terms pretty interchangeably. Both refer to a partial breakdown usually involving the ionization of a gaseous conductor, whether in an insulation void or along the surface of a conductor.

 

[DougMSOE]

Corona takes place in air between an electrically stressed part and the atmosphere.
Partial discharge takes place INTERNAL to a dielectric media.

 

[nostrayvoltage]

DougMSOE
Sorry to disagree, but in reality the term "corona" is also often used to describe partial discharges that occur in voids of solid dielectrics. Likewise the term partial discharge also discribes the ionization around a conductor in air where a complete breakdown of the gap does not occur. The terms are used by and large interchangeabily.

One of my first jobs out of college was to do "corona" testing on underground components (connectors) using solid dielectric. As a college student, I was involved in "corona" testing of EHV overhead transmission line hardware.

 

[ScottyUK]

Hi nostrayvoltage,

From the UK perspective I agree with DougMSOE, although it would not be the first time the US and the UK have been divided by a common language!

 

[nostrayvoltage]

I think this link to ASTM supports my view of the interchangeability of the two terms.

http://www.astm.org/cgi-bin/SoftCart.exe/DATABASE.CART/REDLINE_PAGES/D1868.htm?E+mystore

no_stray_voltage@yahoo.com

 

[jbartos]

Suggestion: References:
1. IEEE Std 100-2000 "Dictionary"
It includes several definitions of Corona, and Corona + , e.g. Corona Charging
1a. Corona (1)(air) A luminous discharge due to ionization of the air surrounding a conductor caused by a voltage gradient exceeding a certain critical value.
(ANSI C57.19.03-1996)
1b. Corona (4) (partial discharge) (corona measurement). A type of localized discharge resulting from gaseous ionization in an insulation system when the voltage stress exceeds a critical value. The ionization is usually localized over a portion of the distance between the electrodes and the system. (IEEE 436-1977)

etc.