Lighting Arrester should be after or before the cutout fuse (which protects the pole mounted XMR)

[abk453]

We have 34.5kV distribution line where the Lightning Arrester(LA) is installed after the fuse and primary side the pole mounted transformer. So, when the lightning hits then fuse blown and create interruption and company losing money because the oil wells do not have power. I am thinking of changing the location of the LA before the fuse so that lightning surge will dissipate through LA and fuse will not be blown which helps to eliminate interruption. Does anyone have any technical suggestions or papers about this . Your comments are really appreciable .

 

[LionelHutz]

Fuse before can lower the transient voltage that reaches the transformer. It's also generally accepted to connect the arrestor as close to the transformer as possible. Still, I see fuse after installations around here so it's done both ways. A Google search on overhead transformer lightning protection should yield lots of information.

 

[davidbeach]

More arrestor locations along the line might help as well. Let a bunch of arrestors share the surge and the current through any one of them will be less. That way you can still leave the arrestors at the transformers as close to the transformer as possible to maximize the protection they provide to the transformer.

 

[dpc]

Also mind the quality of the ground connection to the arrester. As straight and short as possible. And yes, as close to the transformer as possible is always preferred.

 

[abk453]

Thanks all for your suggestions.Actually, the production loss is the big factor here as fuse is before lightning arrester(LA) . My logic is to put LA before fuse to reduce frequent fuse blown which will ultimately reduce oil production loss. I know the lead length is a issue for LA but how circuit will work with LA before the fuse and also reduce the lead length.

 

[crshears]

As long as the per annum economic benefit of reduced production loss due to less interruptions outweighs the cost of replacing failed transformers, LA ahead of fuse is doable; also, davidbeach's point to add more LA's than there are customer taps is in my view excellent advice.

CR

"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]

 

[RRaghunath]

In case of OHL connection to the transformer, it is important to keep the LA as close as possible to the transformer primary terminals.
Some users even insist on LA being part of the transformer (mounted on top of the transformer near bushings) package itself.
Providing additional LAs before the fuses, leaving the LA near transformer terminals as it is could be your option to minimise the outage without sacrificing the protection level of transformer. LAs are low cost items.

 

[PA28]

Just wandering what will happen if the LA fails as a short circuit. At low voltage levels we always use a fuse to isolate the defective surge protection devices.

 

[crshears]

LA fail to a short circuit / negligible impedance state would almost certainly result in its explosive failure, quickly resolving the short circuit issue; the feeder may or may not auto-reclose / blow an upstream fuse, depending mostly on line/source impedance.

CR

"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]