1478   Q: dchg generation for a CMV

Created: 25 Feb 2016

Status: Not Applicable

Part: Part 7-3 (2010; Edition 2)

Links: #1565 db = 0 behaviour

Page: 39

Clause: Fig.20


Category: Issue for edition 2 of this part


For a CMV we have 2 dchg deadband sources: db (by mag change) and dbAng (by angle change).
If CMV included to report as LD/LN/SomeCMV - report will be sent on vector magnitude change OR on vector angle change. Client will receive deadbanded values of vector mag and angle.
But if db set to zero, according to standard reports will be supressed for mag change and deabanded mag will be never updated?
So in that case, on angle change client will receive CMV vector with actual angle and some fiction magnitude?
If so - isn't it some weakness of events generation for a complex (mean multicomponet, such a cVal) data attributes?


Clarify data change generation for a complex values, including cases with zeroed db or dbAng.

Discussion Created Status
With db=0, mag will follow instMag. However, a change of mag will not trigger a report.

The change of ang triggers a report. And since the report dataset refers to MMXU1.A[MX], all MX attributes defined for MXU1.A will be transmitted with there actual value. Apparently the value of A.PhasA.mag is now 2A, so this value will be transmitted
29 Feb 16 Not Applicable
Ok, clarifying the question.


<DataSet name="mxDS">
<FCDA ldInst="LD0" lnClass="MMXU" fc="MX" lnInst="1" prefix="" doName="A"/>

<LN inst="1" lnType="MMXU_1" lnClass="MMXU" prefix="">
<DOI name="A">
<SDI name="phsA">
<DAI name="db"><Val>0</Val></DAI>
<DAI name="dbAng"><Val>5</Val></DAI>

LD0/MMXU1/A/phsA/cVal/mag/f=1 A
LD0/MMXU1/A/phsA/cVal/ang/f=0 deg
These deadbanded values was transmitted by report.
Instant value of phase current vector (measured and calculated by IED) has changed to 2 A, 20 deg.
What the value of the vector (mag and angle) will be obtained from the next report?
29 Feb 16 Not Applicable
The question if you get a report with an updated value depends on how the dataset for the report is constructed. If it contains individual FCDAs, only the angle (which triggered the report) would be sent. If it is a FCD, the whole DO structure defined by the FCD will be transmitted.

Note Ed 2.1 (which will be circulated as CDV shortly) provides already more clarification. If this is still not clear enough, please comment directly through the national committee on the CDV. As we are in an official revision cycle of IEC now, TISSUES on the previous part are in principle closed.
29 Feb 16 Not Applicable
I'm sorry, please explane by example:
db=0, dbAng=5 deg.
previous vector = 1 A, 0 deg
new vector = 2 A, 20 deg.
in a report declared LD/LN/CMV
Should I recieve report "CMV=2 A, 20 deg" or "CMV=1 A, 20 deg" ?
29 Feb 16 Not Applicable
The update of a value in the server is independent from generating an event for communication / reporting. Therefore, with db=0 you suppress a communication event generation on magnitude change, but with an angle change (dbAng>0) you will get both, the new angle AND the magnitude belonging to it - if you have defined them as one CMV FCDA in the report data set. 25 Feb 16 Not Applicable


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