Sunday, June 29, 2014

One Standard – multiple Terms for the same Thing

The Standard series IEC 61850 and IEC 61400-25 define hundreds of new terms for information models and communication models. Usually a term defined in one part and re-used in another part is the same (syntactically and semantically). In some cases you will find different terms for the same “meaning”.

Here is one example to explain what I mean:

The Standard part IEC 61850-7-2 (ACSI) defines in clause

TrgOp [0..2] – trigger option

The attribute TrgOp of type TriggerConditions shall define the trigger conditions (associated to a data attribute of a data object) that may cause a report to be sent or a log entry to be stored into a log.

Three values are defined to be used inside the data object:

dchg data-change A report or a log entry shall be generated due to a change of the value of the associated data attribute

qchg quality-change A report or a log entry shall be generated due to a change of the value of the associated quality data attribute q

dupd data value update A report or a log entry shall be generated due to updating the value of a data attribute. An updated value may have the same value as the old
value. An example is freezing the value of a freezable data attribute updating the value of another data attribute, which could lead to the same value it already has.

The trigger conditions integrity and general-interrogation of the TriggerConditions type are used independent of instances of a data object.

The service parameter IntegrityPeriod is mapped to intgPd: IntgPdintegrity period

IntgPd shall indicate the period in milliseconds used for generating an integrity report.

So far so good – even we have already three terms:

integrity, IntegrityPeriod, IntgPd, or integrity period.

What does part 6 (SCL) define?

<xs:complexType name="tTrgOps">
   <xs:attribute name="period" type="xs:boolean" use="optional" default="false"/>

and for the value attribute of “period”: intgPd="2000" in the report configuration element.

So, we find six terms that mean more or less the same thing … you have to understand what they mean and when to use one or the other!

When it comes to IED Configuration Tools (ICT), you may have to learn new terms again:


Here the SCL attribute “period” is set to true, if the checkbox for “Included in Integrity/Poll” is set.

By the way, these terms describe something quite easy: Push all (!) values of a DataSet every n milliseconds. Without a request from the client. In addition to the cyclic push you may configure the server to report the value of a single signal after it has changed (data change)):


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