198   Instantiation of URCB

Created: 01 Sep 2005

Status: In Force (green)

Part: Part 8-1 (2004)


Page: see issue #114



Issue: In part 6 below table 23 the instantiation of URCB/BRCB is specified as follows:
"The URCName or BRCName of the control block according to IEC 61850-7-2 (clause 14.2.1) is built from the RCName attribute above followed by a two digit number between 01 and max. If ClientLNs are defined, the index (position) of the ClientLN in the list contained in the RptEnabled element is used as this number for this client (the first has index 1). This means that a report control block definition in SCL has to be considered as a type, and not as an instance, which might have 99 instances for 99 clients"

This means that in MMS the URCB reference (instance) is constructed from the SCL RCBname followed by a two digit number. For example the RCBname is "urcbST" and max client is 3 the MMS has (at least):
urcbST01, urcbST02 and urcbST03.

Question: Is this correct and is this mandatory?
When yes all clients can read the SCL and can exactly determine the reference for the RCB. When no, clients can not determine from SCL what the RCB reference will be and this results in an interoperability problem!

The confusion is caused because some servers support option a) "URCB are visible to all clients" and other servers support option b) "URCB is visible to one client only" (option a-b are specified in part 7-2 clause 14.2.1) and there is no parameter in SCL to indicate this difference. In part 8-1 a note recommends a naming convention to resolve this. It would be better if this would be a SCL report setting. Based on this setting the client can determine the instance name of a URCB (and BRCB).

Proposal: - Make the instantiation as described in part 6 mandatory
- add a new SCL report setting to indicate the instantiation mechanism with or without sequence number

Discussion Created Status
Both models in 7-2 need to be reflected in Part 6. Therefore, adding a RCB attribute in SCL to indicate if the RCB is indexed or not. The SCL attribute should be "indexed" (BOOLEAN) TRUE or FALSE.

8-1 needs to be updated to map this new SCL Attribute. This impacts the reccomendations on page 52/53. The 8-1 recommendations should be removed and replaced with:

"If the IEC 61850-6 RCB attribute "index" is TRUE, the RCB (URCB or BRCB) instance numbering shall start with 01 and progress through 99. Two digits of instance numbering is mandatory.

If the IEC 61850-6 RCB attribute "index" is FALSE, the RCB (URCB or BRCB) instance shall be with instance number of 01."

24 Oct 05 Ballot Period


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