scope:

This International Standard is a product family standard applicable to newly manufactured instrument transformers with digital output. The product standard is composed of IEC 61869-1 and IEC 61869-6, in addition to this standard and the relevant specific standard. This standard defines requirements for digital communications of instrument transformer measurements. It is based on the IEC 61850 series of standards, UCA International Users Group document Implementation Guideline for Digital Interface to Instrument Transformers Using IEC 61850-9-2, and IEC 60044-8 which is being replaced by this standard. It includes additional improvements including IEC 61588 network based time synchronization. An illustrative general block diagram of an instrument transformer with digital output is shown in Figure 901. It shows multiple current and/or voltage information coming from the secondary converters (SC in Figure 901) and fed into a common block labelled "merging unit". The merging unit performs all the data processing (sampling, analogue to digital conversion, scaling, message formatting, etc.) necessary to produce a time-coherent output data stream according to this standard. For the purposes of this standard a merging unit is a physical unit (hardware subsystem) used to assemble and transmit digital output data frames.