This part of IEC 61850, which is a Technical Report, describes the methodologies for the modelling of logics for IEC 61850 based applications in power utility automation. In particular, it describes the functional view of logic based on existing logical nodes for generic process automation and the operational modes of the logic. Furthermore it includes the specification of the standard language to be applied to specific the logic as well as the related data exchange format between engineering tools and their application as well as the mapping of logic elements to IEC 61850 data types.

The examples or use cases given in this document are based on the class model introduced in IEC 61850‑7‑1 and defined in IEC 61850‑7‑3. The logical node and data names used in this document are defined in IEC 61850‑7‑4, the services applied in IEC 61850‑7‑2. The naming conventions of IEC 61850‑7‑2 are applied in this document also.

If extensions are needed in the application examples, the normative naming rules for multiple instances and private, compatible extensions of Logical Node (LN) Classes and Data Object Names defined in IEC 61850‑7‑1 are considered.

This document describes the use of IEC 61850 extensions for modelling logics, therefore it implies some tutorial material. However it is advisable to read IEC 61850‑6 and IEC 61850‑7‑1 in conjunction with IEC 61850‑7‑3 and IEC 61850‑7‑2 first and IEC 61131‑3 as reference for the programming language of logic.

The different logics included in any IED in an IEC 61850 based system can be classified into two groups:

The major goal of this document is to adopt the given functionality of an IED to fit to specific application function demands. This is to provide a definition of the methodology for describing and exchanging logics using an IEC 61850 compatible solution. As a benefit the same logic description will be valid and vendor-independent, so it could be used for different IEDs. It is up to the tools to understand this standard description in order to be able to manipulate the logics and to properly configure the IEDs.

Graphical representation of logic is currently out-of-scope of the IEC 61850 series, even if it is part of the PLCopen XML specification. The representation is subject to the engineering tools.

Modelling logics requires some extension of the currently defined data model and / or an extension of the content in the SCL files which is described and which needs to be considered in later editions of IEC 61850‑6 and IEC 61850‑7‑4.

Some examples are included for guidance in Annex B.