IEC 61850 User Feedback Task Force

I guees, that the setting LoSet and HiSet apply the differential protection for power transformer:
LoSet would define the threhold in % for IDiff/InominalAtLowVoltageSide
HiSet would define the threhold in % for IDiff/InominalAtHighVoltageSide

The nominal current of the power transformer is determined by the setting YPTR.VARtg and
- YLTC.HiVRtg for the current at the high voltage side of the power transformer
- YLTC.LoVRtg for the current at the low voltage side of the power transformer

For differential protection for line: the rated current is given at the TCTR.ARtg. However, it is not clear to me if LoSet or HiSet apply to the Line Differentail Protection.

I spoke to one of our protection engineering SMEs and received some more details.

They agreed with the plot that Michael shows in his comment. There are typically two different elements set. One, the Low Set, is for the slope differential. The other, the High Set, is for the instantaneous differential.

Based on the AtMostOne constraint, it appears as if it was intended that two PDIF elements would be used, one for the slope differential and one for the instantaneous differential.

As far as the nominal current, they said that different vendors or relays may set their differential elements using different nominal currents. One relay may use CT current rating as nominal current. Another relay may use the transformer (or some other protected apparatus) rated current as the nominal (I may not have the terms exactly correct here).

They did agree that having a nominal current setting would be useful. However, it has to be general enough that it can apply to the various values used by the different vendors.

Thierry Dufaure wrote in #note-2: - Typo for the HiVRtg / LoVRtg - they are both located in YPTR

I guees, that the setting LoSet and HiSet apply the differential protection for power transformer:
LoSet would define the threhold in % for IDiff/InominalAtLowVoltageSide
HiSet would define the threhold in % for IDiff/InominalAtHighVoltageSide

The nominal current of the power transformer is determined by the setting YPTR.VARtg and
- YPTR.HiVRtg for the current at the high voltage side of the power transformer
- YPTR.LoVRtg for the current at the low voltage side of the power transformer

For differential protection for line: the rated current is given at the TCTR.ARtg. However, it is not clear to me if LoSet or HiSet apply to the Line Differentail Protection.