Faults: Wye Wye versus Delta Wye
Faults: Wye Wye versus Delta Wye
(OP)
Hello,
I am working on a project which called for a 1500 KVA delta-wye transformer (25 kV to 480V). Somehow we ended up with a wye-wye. Assuming the transformer is the same size and impedance, would the change from delta-wye to wye-wye have any detrimental effects on the fault current? Is there any reason to re-do the short circuit and arc flash studies?
EE
I am working on a project which called for a 1500 KVA delta-wye transformer (25 kV to 480V). Somehow we ended up with a wye-wye. Assuming the transformer is the same size and impedance, would the change from delta-wye to wye-wye have any detrimental effects on the fault current? Is there any reason to re-do the short circuit and arc flash studies?
EE






RE: Faults: Wye Wye versus Delta Wye
Gunnar Englund
www.gke.org
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Half full - Half empty? I don't mind. It's what in it that counts.
RE: Faults: Wye Wye versus Delta Wye
RE: Faults: Wye Wye versus Delta Wye
But you may want to review your ground fault relaying.
RE: Faults: Wye Wye versus Delta Wye
Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.
RE: Faults: Wye Wye versus Delta Wye
Thanks again
RE: Faults: Wye Wye versus Delta Wye
Bill
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"Why not the best?"
Jimmy Carter
RE: Faults: Wye Wye versus Delta Wye
RE: Faults: Wye Wye versus Delta Wye
RE: Faults: Wye Wye versus Delta Wye
RE: Faults: Wye Wye versus Delta Wye
EE
RE: Faults: Wye Wye versus Delta Wye
When you say that ETAP calculates min and max faults, if it is based on IEE1584 (most likely) it will be calculating 3 phase fault currents and arcing currents. IEEE1584 recommends calculating trip times at 85% arcing current (for LV systems) as well as 100% to see which scenario gives the highest incident energy, but both are 3 phase values. 85% arcing current results in longer trip times. I am not familiar with ETAP, but SKM PTW calculates the incident energy for both cases and reports the worst case, and I suspect that ETAP does the same.