Thank you 7anoter4 for your detailed response.
The EPRI formula you provided is in the same form as the Kersting formula, the difference being attributable to the resistivity assumption. I came up with 7.07 ohm/mi using the 30 ohm-cmil/ft you sited, versus 3.36 ohm/mi if Kersting's assumed...
I am in the process of calculating sequence impedances for a triplexed 750MCM, 34.5kV, EPR cable with copper tape shield, and am running into some problems.
The cable vendor, Prysmian, provided all the relevant cable data, including a shield resistance of 34.4 ohm/mi, which sounded high to...
There is a 3-50kVA, 13.8 kV wye / 600 V delta connected bank on that circuit, but it is before the recloser. The print shows no ground sources beyond the recloser, but I suppose that could be wrong. I'll have to make some field checks
If you're curious, attached is a fault record from another...
We had an interesting trip the other day. A squirrel got across a normally open tie air break switch between two 13.8kV feeders. Both station breakers tripped correctly, but a downstream recloser on one of the circuits also tripped on ground for some reason. There is no known ground source...
We are running two LTC's in parallel. We have been having a problem recently with a high number of LTC operations on each unit. Closer inspection revealed that the units are "hunting" for a period of a few hours early each morning during light load. As soon as the load comes up, they fall back...
This is what can happen when panels aren't crated for shipping correctly:
www.hged.com/MVC-008F.JPG
www.hged.com/DSC-00943.JPG
www.hged.com/MVC-002F.JPG
Good thing it was FOB.
