IEC 61869-2:2012

IEC 61869-2 ®
Edition 1.0 2012-09
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Instrument transformers –
Part 2: Additional requirements for current transformers

Transformateurs de mesure –
Partie 2: Exigences supplémentaires concernant les transformateurs de courant

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IEC 61869-2 ®
Edition 1.0 2012-09
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Instrument transformers –
Part 2: Additional requirements for current transformers

Transformateurs de mesure –
Partie 2: Exigences supplémentaires concernant les transformateurs de courant

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX XB
ICS 17.220.20 ISBN 978-2-83220-293-7

– 2 – 61869-2 © IEC:2012
CONTENTS
FOREWORD . 5
1 Scope . 8
2 Normative references . 8
3 Terms and definitions . 8
3.1 General definitions . 8
3.3 Definitions related to current ratings . 9
3.4 Definitions related to accuracy . 10
3.7 Index of abbreviations . 18
5 Ratings . 20
5.3 Rated insulation levels . 20
5.3.2 Rated primary terminal insulation level . 20
5.3.5 Insulation requirements for secondary terminals . 20
5.3.201 Inter-turn insulation requirements . 20
5.5 Rated output . 20
5.5.201 Rated output values . 20
5.5.202 Rated resistive burden values . 20
5.6 Rated accuracy class . 21
5.6.201 Measuring current transformers . 21
5.6.202 Protective current transformers . 22
5.6.203 Class assignments for selectable-ratio current transformers . 26
5.201 Standard values for rated primary current . 26
5.202 Standard values for rated secondary current . 27
5.203 Standard values for rated continuous thermal current . 27
5.204 Short-time current ratings . 27
5.204.1 Rated short-time thermal current (I ) . 27
th
5.204.2 Rated dynamic current (I ) . 27
dyn
6 Design and construction . 27
6.4 Requirements for temperature rise of parts and components . 27
6.4.1 General . 27
6.13 Markings . 27
6.13.201 Terminal markings . 27
6.13.202 Rating plate markings . 28
7 Tests . 30
7.1 General . 30
7.1.2 Lists of tests . 30
7.2 Type tests . 31
7.2.2 Temperature-rise test . 31
7.2.3 Impulse voltage withstand test on primary terminals . 33
7.2.6 Tests for accuracy . 33
7.2.201 Short-time current tests . 35
7.3 Routine tests . 36
7.3.1 Power-frequency voltage withstand tests on primary terminals . 36
7.3.5 Tests for accuracy . 36
7.3.201 Determination of the secondary winding resistance (R ) . 38
ct
7.3.202 Determination of the secondary loop time constant (T ) . 38
s
61869-2 © IEC:2012 – 3 –
7.3.203 Test for rated knee point e.m.f. (E ) and exciting current at E . 39
k k
7.3.204 Inter-turn overvoltage test . 39
7.4 Special tests . 40
7.4.3 Measurement of capacitance and dielectric dissipation factor . 40
7.4.6 Internal arc fault test . 40
7.5 Sample tests . 41
7.5.1 Determination of the remanence factor . 41
7.5.2 Determination of the instrument security factor (FS) of
measuring current transformers . 41
Annex 2A (normative) Protective current transformers classes P, PR . 42
Annex 2B (normative) Protective current transformer classes for transient
performance . 47
Annex 2C (normative) Proof of low-leakage reactance type . 63
Annex 2D (informative) Technique used in temperature rise test of oil-immersed
transformers to determine the thermal constant by an experimental estimation . 64
Annex 2E (informative) Alternative measurement of the ratio error (ε) . 66
Annex 2F (normative) Determination of the turns ratio error . 68

Figure 201 – Duty cycles . 15
Figure 202 – Primary time constant T . 16
P
Figure 203 – Secondary linked flux for different fault inception angles γ . 17
Figure 2A.1 – Vector Diagram . 42
Figure 2A.2 – Error triangle . 43
Figure 2A.3 – Typical current waveforms . 44
Figure 2A.4 – Basic circuit for 1:1 current transformer . 44
Figure 2A.5 – Basic circuit for current transformer with any ratio. 45
Figure 2A.6 – Alternative test circuit . 45
Figure 2B.1 – Short-circuit current for two different fault inception angles . 48
Figure 2B.2 – ψ (t) as the curve of the highest flux values, considering all relevant
max
fault inception angles γ . 48
Figure 2B.3 – Relevant time ranges for calculation of transient factor . 49
Figure 2B.4 – Determination of K
in time range 1 at 50 Hz for T = 1,8 s . 50
tf s
Figure 2B.5 – Determination of K in time range 1 at 60 Hz for T = 1,5 s . 50
tf s
Figure 2B.6 – Determination of K in time range 1 at 16,7 Hz for T = 5.5 s . 50
tf s
Figure 2B.7 – Limiting the magnetic flux by considering core saturation . 52
Figure 2B.8 – Basic circuit . 53
Figure 2B.9 – Determination of remanence factor by hysteresis loop . 55
Figure 2B.10 – Circuit for d.c. method . 56
Figure 2B.11 – Time-amplitude and flux-current diagr
...