87T Vs. 87REF
87T Vs. 87REF
(OP)
what is the need for a REF on a wye-wye grounded 15 MVA trafo if a full differential (87T) is provided? I think that any winding to yoke fault on secondary or primary will be detected by the 87T and the OC/EF provides back up protection.
any clue?
any clue?






RE: 87T Vs. 87REF
RE: 87T Vs. 87REF
RE: 87T Vs. 87REF
RE: 87T Vs. 87REF
Now regarding the advantage of having REF.
If any of the winding neutral is resistively earthed, probably the sensitivity of 87T may not be adequate to cover the faults which are close to the neutral point. The REF has an edge over 87T for such faults.
RE: 87T Vs. 87REF