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Despite the seemingly logical conclusion that an IEC 61850 device supporting say disturbance recording should provide RDRE and the individual channel RABR and RBDR, the Standard does not mandate the modelling chosen by the manufacturer must include these Logical Nodes.

Nor does the Standard mandate that a distance relay has to use a PDIS, and a differential relay is not mandated to have a PDIF.  It is totally up to the vendor to decide what and how to implement IEC 61850 so if they want to have a distance relay but want to exclude the distance function from the scope of the IEC 61850 model, they can do that - perhaps ridiculous to make a conscious decision to do that but it is possible and permit-able.

  • I know of one utility who called for samples of IEC 61850 conforming line differential relays for tender evaluation - one vendor supplied a sample relay with LOTS of LN of all sorts EXCEPT PDIF - none at all!  The IED however has a valid Conformance Certificate issued by KEMA
  • I also know of a university as specialists in teaching of IEC 61850 who obtained various relays "compliant to IEC 61850" in order that they do some research of sampled values - however the relays they obtained did not provide IEC 61850 - 9-2 nor 9-2LE either in subscribing to or publishing Sampled Values
  • I also know of a utility investigating some new products on the market which ONLY had LLN0 implemented in the device - but of course still had a Conformance Certificate.

That is probably a big epiphany for many.

LNs are MODELS of functions.

If a supplier CHOOSES to model a function with IEC 61850, then that model must conform to the LN structure defined in Part 7-4.

i.e. which LNs they provide is TOTALLY OPTIONAL.

Furthermore, within the LN Model itself there are Mandatory, Optional and Conditional Data Objects and Attributes according to the vendor's chosen 'depth' of modelling - hence for example they don't necessarily have to provide any setting Data Objects for a PDIS - they are ALL Optional Data Objects.  The only PDIS Mandatory Data Objects for PDIS are .Str and .Op

Conclusion:  You only can expect to get what you specify - that requires to the DETAIL of:

  1. Which TYPE of LNs
  2. How MANY of each type of LN
  3. Which Optional and Conditional DATA OBJECTS to be provided
  4. Which Optional and Conditional ATTRIBUTES to be provided

Many Procurement specifications for relays and/or systems often end up not being of any practical benefit towards getting what you need:
(refer these 3 real specification examples - click to enlarge)

:

These specifications are akin to buying a car based on the sole requirement  "all cars shall be drivable on tarred roads".

What do Conformance Certificates actually certify

There is much controversy - rather misunderstanding - of what Certification means, especially the wording of the Certificates.

The wording of the Certificates seems a bit confusing: "NOT BEEN SHOWN TO BE NON-COMPLIANT"
This means that the certification laboratory has undertaken the prescribed testing of the IED and it did not fail. 

This is a correct 'legal' statement of what was done.

The IEC 61850 Certification process is defined in IEC 61850 Part 10.

A vendor must declare what they want certified.  

The Certification Laboratory will then test the things the vendor has requested to be certified that whatever has been implemented has NOT BEEN SHOWN TO BE NON-COMPLIANT
Hence the above example of a Certified IED only having a LLN0 which was "not implemented incorrectly".

Certification does not include proving that the vendors chosen functions and modelling thereof makes any sense from an application or usage point of view.
This, as always, is the responsibility of the purchaser to specify and verify they get the "things" they need for their application.

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