Two bundles one tower

[HamburgerHelper]

I have a tower with two bundles that are on the same circuit. The problem that I am running into is that the relaying under reaches for a fault on one bundle due to the parallel flow on the other bundle. This has to be a problem that has been solved a long time ago. Do you usually just put more margin into your settings? Is there no nice solution? Am I just use the wrong terms and that is why I can't find anything on this?

 

[Mbrooke]

Question. Have you considered "fusing" the circuits together every kilometer? I'd think this would lower the impedance of any fault involved.

 

[davidbeach]

Yep, you're going to need to install jumpers between the two sides. May not need to be every km though; when I faced that problem a while back I found that 3 jumpers would generally be enough. Try jumpers at about 25%, 50%, and 75% of the line.

 

[HamburgerHelper]

The jumpers were my first thought ,too, but I had hoped there was a maybe a non-physical solution.

 

[Mbrooke]

MY second choice would be using differential protection for the line, but thats only if adequate communication exists or can be justified. But considering all the other physical work one might encounter, line jumpers are perhaps the easiest.

 

[davidbeach]

A few crew hours are far less expensive and disruptive than new relays. I certainly wouldn't mind differential on the examples we have, but one of the worst still has electromechanical relays on one of the terminals (3 terminal line with two conductors per phase on two of the three legs). I'm guessing that it's more likely that the line will go away in few years than that we'll get to put new relays on all three terminals.

 

[Mbrooke]

Id say so too. Hope everything gets sorted out with that line, not something I would feel comfortable with.