IEC TR 61000-3-7:2008

IEC/TR 61000-3-7
Edition 2.0 2008-02
TECHNICAL
REPORT
BASIC EMC PUBLICATION
Electromagnetic compatibility (EMC) –
Part 3-7: Limits – Assessment of emission limits for the connection of
fluctuating installations to MV, HV and EHV power systems

IEC/TR 61000-3-7:2008(E)
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IEC/TR 61000-3-7
Edition 2.0 2008-02
TECHNICAL
REPORT
BASIC EMC PUBLICATION
Electromagnetic compatibility (EMC) –
Part 3-7: Limits – Assessment of emission limits for the connection of
fluctuating installations to MV, HV and EHV power systems

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
XB
CODE PRIX
ICS 33.100.10 ISBN 2-8318-9606-1

– 2 – TR 61000-3-7 © IEC:2008(E)
CONTENTS
FOREWORD.5
INTRODUCTION.7
ACKNOWLEDGMENT.8

1 Scope.9
2 Normative references .10
3 Terms and definitions .10
4 Basic EMC concepts related to voltage fluctuations.13
4.1 Compatibility levels .14
4.2 Planning levels.14
4.2.1 Indicative values of planning levels.14
4.2.2 Assessment procedure for evaluation against planning levels.15
4.3 Illustration of EMC concepts.16
4.4 Emission levels .17
5 General principles .18
5.1 Stage 1: simplified evaluation of disturbance emission .18
5.2 Stage 2: emission limits relative to actual system characteristics.18
5.3 Stage 3: acceptance of higher emission levels on a conditional basis.19
5.4 Responsibilities .19
6 General guidelines for the assessment of emission levels .19
6.1 Point of evaluation.19
6.2 Definition of flicker emission level .20
6.3 Assessment of flicker emission levels.20
6.4 Declared system short circuit power or impedance .21
6.4.1 Short-circuit power or impedance for pre-connection assessment of
emission levels.21
6.4.2 Short-circuit power or impedance for assessing actual emission
levels.21
6.5 General guidelines for assessing the declared system impedance.21
7 General summation law .21
8 Emission limits for fluctuating installations connected to MV systems .22
8.1 Stage 1: simplified evaluation of disturbance emission .22
8.2 Stage 2: emission limits relative to actual system characteristics.23
8.2.1 Global emission to be shared between the customers.23
8.2.2 Individual emission limits .24
8.3 Stage 3: acceptance of higher emission levels on a conditional basis.25
8.4 Summary diagram of the evaluation procedure .26
9 Emission limits for fluctuating installations connected to HV or EHV systems .28
9.1 Stage 1: simplified evaluation of disturbance emission .28
9.2 Stage 2: emission limits relative to actual system characteristics.28
9.2.1 Assessment of the total available power .28
9.2.2 Individual emission limits .29
9.3 Stage 3: acceptance of higher emission levels on a conditional basis.30
10 Rapid voltage changes .31
10.1 General considerations.31
10.2 Compatibility level .32

TR 61000-3-7 © IEC:2008(E) – 3 –
10.3 Planning levels.32
10.4 Emission limits .33
10.5 Assessment procedure for evaluation against planning levels & emission
limits .33

Annex A (informative) P = 1 curves and numerical data for 230 V and 120 V

st
applications .34
Annex B (informative) Guidelines on the assessment of flicker transfer coefficient.36
Annex C (informative) Example of reallocation of global contributions and planning
levels considering transfer coefficients.37
Annex D (informative) The use of the severity indicators A and A to simplify
st lt
calculations.39
Annex E (informative) Pre-connection and post-connection assessment of emission for
P .40
st
Annex F (informative) Addition of P from different busbars.49
st
Annex G (informative) Examples of case studies .51
Annex H (informative) List of symbols and subscripts .62

Bibliography.64

Figure 1 – Illustration of basic voltage quality concepts with time/ location statistics
covering the whole system.17
Figure 2 – Illustration of basic voltage quality concepts with time statistics relevant to
one site within the whole system.
Figure 3 – Example of a system for sharing global contributions at MV .23
Figure 4 – Diagram of evaluation procedure.27
Figure 5 – Determination of S for a simple HV or EHV system.28
t
Figure 6 – Determination of S for a meshed HV or EHV system .29
t
Figure 7 – Equivalent circuit and vector diagram for simple assessments .31
Figure 8 – Example rapid voltage change associated with motor starting .31
Figure 9 – Example rapid voltage change associated with capacitor switching .32
Figure A.1 – P = 1 curve for regular rectangular voltage changes [13].34
st
Figure E.1 – Shape factor curve for pulse and ramp changes .41
Figure E.2 – Shape factor curves for double-step and double-ramp changes .42
Figure E.3 – Shape factor curves for sinusoidal and triangular changes.42
Figure E.4 – Shape factor curves for aperiodic changes .43
Figure E.5 – Accounting for network loading .45
Figure E.6 – System for flicker emission assessment.47
Figure E.7 – Assessment of emission level using current measurements .48
Figure F.1 – Example of two loads fed from different busbars .49
Figure G.1 – Example of effect from a rolling mill.51
Figure G.2 – Example of effect of multiple spot welder load .53
Figure G.3 – Example profile of winder reactive power levels.57
Figure G.4 – Normal system configuration .
...