wye-delta overvoltage backfeed
wye-delta overvoltage backfeed
(OP)
In another thread, Waross spoke having experience with these wye-deltas. I'm hoping he will respond along with anyone else with experience in the matter.
We recently had some damage when a fuse opened and backfeed on the downstream side of that phase occurred from an ungrounded wye-delta bank. When doing a bit of searching on the subject, I came across IEEE C62.22 which shows how an arrester could experience as much as 2.7 per unit voltage for this condition when load is unbalanced (situation normal). Sounds like an extreme disadvantage for so common a connection. Is this your experience? Thanks.
We recently had some damage when a fuse opened and backfeed on the downstream side of that phase occurred from an ungrounded wye-delta bank. When doing a bit of searching on the subject, I came across IEEE C62.22 which shows how an arrester could experience as much as 2.7 per unit voltage for this condition when load is unbalanced (situation normal). Sounds like an extreme disadvantage for so common a connection. Is this your experience? Thanks.






RE: wye-delta overvoltage backfeed
RE: wye-delta overvoltage backfeed
I once found an REA publication which recommended floating the wye point if the wye/delta connection was used.
That avoids the circulating currents but introduces the possibility of transient overvoltages during switching.
Bill
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"Why not the best?"
Jimmy Carter