IEC 61869-2:2012/ISH1:2022

IEC 61869-2:2012/ISH1:2022 – 1 –
© IEC 2022
INTERNATIONAL ELECTROTECHNICAL COMMISSION
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IEC 61869-2
Edition 1.0  2012-09


INSTRUMENT TRANSFORMERS –

Part 2: Additional requirements for current transformers


INTERPRETATION SHEET 1



This interpretation sheet has been prepared by IEC Technical Committee 38: Instrument
transformers.
The text of this interpretation sheet is based on the following documents:
DISH Report on voting
38/687/DISH 38/692/RVDISH

Full information on the voting for the approval of this interpretation sheet can be found in the
report on voting indicated in the above table.

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5.6.201.3 Limits of ratio error (ε) and phase displacement for measuring current
transformers
BACKGROUND:
Subclause 5.6.201.3 states the following:
...For all classes, the burden shall have a power-factor of 0,8 lagging except that, when
the burden is less than 5 VA, a power-factor of 1,0 shall be used, with a minimum value
of 1 VA.
QUESTION:
How shall this sentence be interpreted when the rated output is above 5 VA, but the test burden
for the test at 25 % of the rated output is below 5 VA?
For example, when testing a current transformer with a rated output of 10 VA, the test burden
at 25 % of the rated output is 2,5 VA. Shall this test burden be at power factor 1,0 or 0,8?
ICS 17.220.20
IEC 61869-2:2012-09/ISH1:2022-01(en)

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© IEC 2022
INTERPRETATION:
The "burden" mentioned in the above-stated sentence of 5.6.201.3 is to be understood as the
"test burden" and therefore in the proposed example the test at 2,5 VA has to be carried out at
power factor 1,0.
Rationale: The sentence under discussion is about the burden connected to the current
transformer during the accuracy test. This is the understanding of manufacturers, metrological
institutes and test laboratories.
This is also reflected in the commercially available test burdens used for accuracy testing of
current transformers. These burdens have the possibility to choose values of 5 VA and above
with a power factor of 0,8 and values below 5 VA with a power factor of 1,0. The minimum test
burden is 1 VA.
For the above-mentioned reasons, it is logical to conclude that:
• the power factor value is 0,8 for test burdens of 5 VA and above,
• the power factor value is 1,0 for test burdens of less than 5 VA,
• 1 VA is the minimum value for the rated output, as well as for the test burden.
Some users need to compare accuracy measurements at 25 % and 100 % of the rated output
with the same power factor of 0,8. The best wa
...