Re: LF: Corona Discharge - how to prevent ?

["James Moritz" <james.moritz@btopenworld.com>]

Dear Graham, Alan, LF Group,

Corona rings as in the attachment have served me well over the years - they 
do seem to substantially increase the voltage at which the onset of corona 
happens. I doubt if multiple rings, spheres etc. will be much improvement, 
since then the maximum potential gradient will then just occur around the 
wire in the middle of the span instead of  at the ends, and the corona will 
move to that point. When I first started fitting them, I found that adding 
the corona ring would get rid of the corona at one end or sharp bend of the 
wire, only for it to reappear at a different point, until all ends and 
corners, and the connection to the loading coil, were so "protected".  Make 
sure there are no loose ends of wire hanging out. Also, try to maximise the 
distance between the wire and any other conducting objects, even poor 
conductors like trees, woodwork, masonry, etc.
Cheers, Jim Moritz
73 de M0BMU

corona_ring.jpg
Description: JPEG image