IEC 62475:2010 is applicable to high-current testing and measurements on both high-voltage and low-voltage equipment. It deals with steady-state and short-time direct current (as e.g. encountered in high-power d.c. testing), steady-state and short-time alternating current (as e.g. encountered in high-power a.c. testing), and impulse-current. In general, currents above 100 A are considered in this International Standard, although currents less than this can occur in tests. This standard also covers fault detection during, for example, lightning impulse testing.

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7	English CONTENTS
13	1 Scope 2 Normative references 3 Terms and definitions
14	3.1 Measuring systems 3.2 Components of a measuring system
15	3.3 Scale factors
16	3.4 Rated values 3.5 Definitions related to the dynamic behaviour
17	3.6 Definitions related to uncertainty Figures Figure 1 – Examples of amplitude frequency responses for limit frequencies (f1; f2) Upper and lower limits frequencies are shown on curve A. Curve B shows a constant response down to direct current
19	3.7 Definitions related to tests on measuring systems
20	4 Procedures for qualification and use of a measuring system 4.1 General principles 4.2 Schedule of performance tests 4.3 Schedule of performance checks
21	4.4 Requirements for the record of performance 4.5 Operating conditions
22	4.6 Uncertainty
23	5 Tests and test requirements for an approved measuring system 5.1 General requirements 5.2 Calibration – Determination of the scale factor
25	Figure 2 – Calibration by comparison over full assigned measurement range
26	Figure 3 – Uncertainty contributions of the calibration (example with the minimum of 5 current levels)
27	Figure 4 – Calibration by comparison over a limited current range with a linearity test (see ‎5.3) providing extension up to the largest value in the assigned measurement range
28	5.3 Linearity test
29	5.4 Dynamic behaviour Figure 5 – Linearity test of the measuring system with a linear device in the extended voltage range
30	5.5 Short-term stability
31	Figure 6 – Short-term stability test for steady-state current Figure 7 – Short-term stability test for impulse current and short-time current
32	5.6 Long-term stability 5.7 Ambient temperature effect Figure 8 – Short-term stability test for periodic impulse-current and periodic short-time current
33	5.8 Effect of nearby current paths
34	Figure 9 – Test circuit for effect of nearby current path for current-converting shunts and current transformers with iron Figure 10 – Test circuit for effect of nearby current path for inductive measuring systems without iron (Rogowski coils)
35	5.9 Software effect 5.10 Uncertainty calculation
37	5.11 Uncertainty calculation of time-parameter measurements (impulse currents only)
39	5.12 Interference test
40	Figure 11 – Principle of interference test circuit Figure 12 – Interference test on the measuring system i1(t) based on current converting shunt or current transformer with iron in a typical 3 phase short circuit set up (example)
41	5.13 Withstand tests Figure 13 – Test circuit for interference test for inductive systems without iron
42	6 Steady-state direct current 6.1 Application 6.2 Terms and definitions 6.3 Test current
43	6.4 Measurement of the test current Tables Table 1 – Required tests for steady-state direct current
44	6.5 Measurement of ripple amplitude
45	Table 2 – Required tests for ripple current
46	6.6 Test procedures 7 Steady-state alternating current 7.1 Application 7.2 Terms and definitions 7.3 Test current
47	7.4 Measurement of the test current
48	Figure 14 – Acceptable normalized amplitude-frequency response of an a.c. measuring system intended for a single fundamental frequency fnom
49	Figure 15 – Acceptable normalized amplitude-frequency response of an a.c. measuring system intended for a range of fundamental frequencies fnom1 to fnom2 Table 3 – Required tests for steady-state alternating current
50	7.5 Test procedures 8 Short-time direct current 8.1 Application
51	8.2 Terms and definitions Figure 16 – Example of short-time direct current
52	8.3 Test currents 8.4 Measurement of the test current Table 4 – Tolerance requirement on test-current parameters for short-time direct current
53	Table 5 – Required tests for short-time direct current
54	8.5 Test procedures 9 Short-time alternating current 9.1 Application
55	9.2 Terms and definitions Figure 17 – Example of short-time alternating current
56	9.3 Test current Table 6 – Tolerance requirements on the short-time alternating current test parameters
57	9.4 Measurement of the test current Table 7 – List of typical tests in a high-power laboratory and required minimum frequency range of the measuring system
58	Table 8 – Tolerance requirements on scale factor Table 9 – Required tests for short-time alternating current
60	9.5 Test procedures 10 Impulse currents 10.1 Application 10.2 Terms and definitions
61	Figure 18 – Exponential impulse current Figure 19 – Exponential impulse current – Oscillating tail
62	Figure 20 – Impulse current – Rectangular, smooth Figure 21 – Impulse current – Rectangular with oscillations
64	10.3 Test current Table 10 – Examples of exponential impulse-current types
65	10.4 Measurement of the test current
67	Table 11 – Required tests for impulse current
68	10.5 Test procedures 11 Current measurement in high-voltage dielectric testing 11.1 Application 11.2 Terms and definitions
69	11.3 Measurement of the test current Table 12 – Required tests for impulse current in high-voltage dielectric testing
70	11.4 Test procedures 12 Reference measuring systems 12.1 General 12.2 Interval between subsequent calibrations of reference measuring systems
71	Annex A (informative) Uncertainty of measurement
76	Table A.1 – Coverage factor k for effective degrees of freedom νeff (p = 95,45 %)
77	Table A.2 – Schematic of an uncertainty budget
78	Figure A.1 – Normal probability distribution p(x) of a continuous random variable x Figure A.2 – Rectangular symmetric probability distribution p(x) of the estimate x of an input quantity X
79	Annex B (informative) Examples of the uncertainty calculation in high-current measurements
81	Table B.1 – Result of the comparison measurement Table B.2 – Result of the comparison measurement
82	Table B.3 – Uncertainty budget for calibration of scale factor Fx
83	Table B.4 – Result of linearity test
84	Figure B.1 – Comparison between the system under calibration X and the reference system N Table B.5 – Uncertainty budget of scale factor FX,mes
85	Annex C (informative) Step-response measurements Figure C.1 – Circuit to generate current step using a coaxial cable Figure C.2 – Circuit to generate current step using a capacitor
87	Figure C.3 – Definition of response parameters with respect to step response
88	Annex D (informative) Convolution method for estimation of dynamic behaviour from step-response measurements
91	Annex E (informative) Constraints for certain wave shapes Figure E.1 – Attainable combinations of time parameters (shaded area) for the 8/20 impulse at maximum 20 % undershoot and for 20 % tolerance on the time parameters
92	Figure E.2 – Locus for limit of attainable time parameters as a function of permissible undershoot for the 8/20 impulse Figure E.3 – Locus for limit of attainable time parameters as a function of permissible undershoot for the 30/80 impulse
93	Annex F (informative) Temperature rise of measuring resistors
94	Annex G (informative) Determination of r.m.s. values of short-time a.c. current Figure G.1 – Equivalent circuit of short-circuit test
95	Figure G.2 – Symmetrical a.c. component of an alternating short-circuit current
96	Figure G.3 – Numerical evaluation of r.m.s value showing both instantaneous current and instantaneous squared value of the current
97	Figure G.4 – Three-crest method
98	Figure G.5 – Evaluation of conventional r.m.s. value of an arc current using the three-crest method
99	Figure G.6 – Evaluation of equivalent r.m.s value of a short-time current during a short-circuit test
100	Figure G.7 – Relation between peak factor k and power factor cos(q).
101	Annex H (informative) Examples of IEC standards with high-current tests Table H.1 – List of typical tests with short-time alternating current
102	Table H.2 – List of typical tests with exponential impulse current Table H.3 – List of typical tests with rectangular impulse current
103	Bibliography

Published By	Publication Date	Number of Pages
BSI	2010	108


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Status	Under Review
Pages	108
Publication Date	2010-12-31
ISBN	978 0 580 56946 3
Standard Number	BS EN 62475:2010
Title	High-current test techniques. Definitions and requirements for test currents and measuring systems
Identical National Standard Of	IEC 62475:2010, EN 62475:2010
Descriptors	Electrical measuring instruments, High voltage, High-voltage tests, Measurement characteristics, Test equipment, Direct current, Electric current, Electrical measurement, Impulse-voltage tests, Alternating current, Low-voltage equipment, Electrical testing, High-voltage equipment, Estimation
Publisher	BSI
Committee	PEL/42
ICS Codes	19.080 - Electrical and electronic testing

BS EN 62475:2010

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