lightning arresters and cutouts on 25kV lines
lightning arresters and cutouts on 25kV lines
(OP)
Looking for anyone from an electric utility with experience on the use of lightning arresters on distribution lines, particularly using a lightning arrester in front of a cutout in an attempt to save the fuse from blowing when a lightning strike occurs. If you have actual experience before and after installing LAs I would certainly appreciate hearing from you.
K2ofKeyLargo






RE: lightning arresters and cutouts on 25kV lines
Articles from Hubbellpowersystems may be of interesting:
http://ww
RE: lightning arresters and cutouts on 25kV lines
Hope this helps.
RE: lightning arresters and cutouts on 25kV lines
The enclose site discuss this issue briefly. http://www.sandc.ca/webzine/050602_1.asp
RE: lightning arresters and cutouts on 25kV lines
cheers!
RE: lightning arresters and cutouts on 25kV lines
1. the line should be bult with a protectiove conductor above
2. If the line is an existing one, can be improved by installing from place to place a set of surge arresters - for examople, each 1-2miles; this will have the effect of stopping the surge on line, before reaching critical equipment. How many you install depend on the isokeraunic indices of your area.
Still, more than likely is a problem of insualtion coordination (chek the BILs)
RE: lightning arresters and cutouts on 25kV lines
If the arrester is placed ahead of the cutout, then the protective level of the equipment is reduced because the arrester lead length between the arrester ground and the equipment ground will be longer. This is because the surge current through the arrester will have to flow through the arrester ground lead and there will be an inductive (L·di/dt) voltage buildup in the lead. The inductive voltage will add to the arrester voltage so that a higher voltage will be impressed on the equipment. You want to keep lead lengths that carry the surge in parallel with the equipment as short as possible.
If the arrester is placed after the cutout, then the lightning surge current will flow through the fuse and you might get nuisance fuse blowing. You can get high surge fuse links to reduce this. The article referenced by cuky2000 discusses this and provides some probability curves of the fuse link blowing.
RE: lightning arresters and cutouts on 25kV lines
Admittedly, surge arresters cost money - but so do fuses - AND re-fusing. Unless you're in a high isokeraunic area I think I'd just fuse and let nature take her course.
RE: lightning arresters and cutouts on 25kV lines