AS 61869.4:2021 Instrument transformers Part 4: Additional requirements for combined transformers (IEC 61869-4:2013 (ED.1.0) MOD).
This part of IEC 61869 applies to newly-manufactured combined transformers for use with electrical measuring instruments and electrical protective devices at frequencies from 15 Hz to 100 Hz.
The requirements and tests of this standard, in addition to the requirements and tests of IEC 61869-1, IEC 61869-2 and IEC 61869-3 cover current and inductive voltage transformers that are necessary for combined instrument transformers.
2 Normative references
Clause 2 of IEC 61869-1:2007 is applicable with the following modifications:
IEC 60028, International Standard of resistance for copper
IEC 60038, IEC standard voltages
IEC 61869-1:2007, Instrument Transformers — Part 1: General requirements
IEC 61869-2:2012, Instrument Transformers — Part 2: Additional requirements for current transformers
IEC 61869-3:2011, Instrument Transformers — Part 3: Additional requirements for inductive voltage transformers
3 Terms, definitions and abbreviations
For the purposes of this document, the terms and definitions given in IEC 61869-1:2007, IEC 61869-2:2012 and IEC 61869-3:2011, as well as the following apply.
3.1 General definitions
combined instrument transformer
instrument transformer consisting of a current and a voltage transformer in the same enclosure
error of voltage transformer
ratio error of voltage transformer determined with disconnected current transformer
4 Normal and special service conditions
Clause 4 of IEC 61869-1:2007 is applicable.
Clause 5 of IEC 61869-1:2007, Clause 5 of IEC 61869-2:2012 and Clause 5 of IEC 61869- 3:2011 are applicable with the following modifications:
5.401 Additional requirements for measuring and protective combined transformer
The error limits for measuring combined transformers shall correspond to the requirements for measuring current transformers, indicated in 5.6.201 of IEC 61869-2:2012, and to the requirements for measuring voltage transformers indicated in 5.6.301 of IEC 61869-3:2011. The limits of error for protective combined transformers shall correspond to the requirements for protective current transformers indicated in 5.6.202 of IEC 61869-2:2012, and to the requirements for protective voltage transformers indicated in 5.6.302 of IEC 61869-3:2011.
5.401.2 Mutual influence
When operating the current transformer between 5 % of the rated current and the rated continuous thermal current, the voltage transformer shall not exceed the limits of voltage error and phase displacement corresponding to its class within the specified range of burden and between 80 % and 120 % of the rated voltage.
When operating the voltage transformer between 80 % of the rated voltage and the rated voltage multiplied by the rated voltage factor, the current transformer shall not exceed the limits of current error and phase displacement within the range of current corresponding to its class and within the specified range of burden.
See 188.8.131.521 and 184.108.40.2062 and Annex 4A.
6 Design and construction
Clause 6 of IEC 61869-1:2007, Clause 6 of IEC 61869-2:2012 and Clause 6 of IEC 61869-3:2011 are applicable with the following modifications:
6.4 Requirements for temperature rise of parts and components
Subclause 6.4.1 of IEC 61869-2:2012 is applicable with the following modifications.AS 61869.4 pdf download.