Spacing requirements between the phases of open AL tubular bus
Spacing requirements between the phases of open AL tubular bus
(OP)
We are installing a new maintanenace transformer that will be fed from 4 different 15kV circuits.
Only one circuit at a time will ever power this transformer. Most of the existing feeders to the existing transformers are fed with aluminum pipe. And that is what we want to do here. The circuits are 15kV phase to phase.
I'm looking at the NEC Table 490.24 that indicates to to get a BIL of 110kV, we need at least 10.5 inches between the phases and 10 inches to a grounded surface.
It's been suggested a couple of different configurations. One would give us more space but would involve bringing one of the phases underneath the other two, and not exactly an equal distance away from the other phases. It seems there may be some type design flaw we aren't thinking of? Is there some kind of transformer action this would cause?
I sketched this out to make what I'm speaking of much clearer...but I can't figure out how to make an attachment with the new "Start a New Thread" input screen. Anyone know how to do this?
Only one circuit at a time will ever power this transformer. Most of the existing feeders to the existing transformers are fed with aluminum pipe. And that is what we want to do here. The circuits are 15kV phase to phase.
I'm looking at the NEC Table 490.24 that indicates to to get a BIL of 110kV, we need at least 10.5 inches between the phases and 10 inches to a grounded surface.
It's been suggested a couple of different configurations. One would give us more space but would involve bringing one of the phases underneath the other two, and not exactly an equal distance away from the other phases. It seems there may be some type design flaw we aren't thinking of? Is there some kind of transformer action this would cause?
I sketched this out to make what I'm speaking of much clearer...but I can't figure out how to make an attachment with the new "Start a New Thread" input screen. Anyone know how to do this?






RE: Spacing requirements between the phases of open AL tubular bus
RE: Spacing requirements between the phases of open AL tubular bus
RE: Spacing requirements between the phases of open AL tubular bus
I would at least look at the NESC.
Check out the BurRec substaion manual- it's good and it free.
RE: Spacing requirements between the phases of open AL tubular bus
I did improve the design some by reversing the phase sequence on one pair of the switches. See the attached.
RE: Spacing requirements between the phases of open AL tubular bus