IEC61850-7-5 #7248
Calculation of the common position for single-phase monitored equipment
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Description
Clause 5.2.1 of the existing document 7-5 states
"
b) If the information of the single phase XCBR.Pos are of different values, then the common
– XCBR.Pos.stVal shall be ‘bad’
"
Are we sure that "bad" is the most appropriate value? During operational situations of phase discrepancy the position would be stated "bad" temporarly.
This entry is linked in some way with #7045 .
Also to be decided whether Clause 5.2 should remain limited to circuit breakers (... mentioning "XCBR" only) or whether it is also applicable to switches.
Updated by Vladan Cvejic 7 days ago
Just a thought - In past, we were using DBI - 'Don't believe indication' as a synonym to 00 and 'Faulty' for 11 value (source: https://standards.globalspec.com/std/9949928/ng-tgn-e-213 ).
Just found out that in modern slang it is 'Don't believe it'.
Otherwise, 'bad' as a word is not forbidden by Non-inclusive terms and recommended alternatives for ISO and IEC documents
Updated by Michael Haecker 6 days ago
It is not the term "bad" as such which I am questioning, it is the semantic associated with "bad". (We are talking about the 'stVal', not the 'q'.)
During operation there will be different timings between the positions of the poles. If the rule from clause 5.2.1 was applied, then the common position would immediately go to "bad" each time when a discrepancy between the positions of the three poles is detected. Will this cause unneccessary alarming?
Should we change "bad" to "intermediate"?
Updated by Vladan Cvejic 6 days ago
From the definition of DpStatusKind:
intermediate-state=0, Equipment is in intermediate state.
off=1, Equipment is open.
on=2, Equipment is closed.
bad-state=3, The server cannot detect whether the position is open (off), closed (on) or in intermediate state.
Bad-state = 11 - means that our wired information is inappropriate (both potentials are high).
We could use DscDlTmms (Discrepancy between phases delay setting) to suppress false alarms for intermediate-state transition.
If we are talking about steady state, where abovementioned timeout passed and single phase is, for example, in position Open and two others are in position Close - I would also go for an Intemediate-state (all open contacts are in series, all close contacts are in series thus if one in open-sequence is closed and others open, and one in close-sequence is open and others closed -> resulting potentials would be No-potential, No-potential = 00 -> intermediate state).
Updated by Michael Haecker 6 days ago
In 7-5 clause 5.2.1 there is no reference to DscDlTmms or the suppression of positions as we do in 7-500 clause 10.1.1.2 Pole discrepancy. In 7-5 we describe how the common signal is calculated. We could introduce the notion of position suppression via DscDlTmms.
Generally speaking, if the common XCBR LN instance does not implement pole discrepancy treatment, then it will publish a "flickering" of "bad" position signals, first, when leaving the start position and again when reaching the end position.
To use the "intermediate" position in such cases seems to be more meaningful.