IEC TS 62749:2015

Assessment of power quality - Characteristics of electricity supplied by public networks

IEC TS 62749:2015(E) specifies the expected characteristics of electricity at the SUPPLY TERMINALS of public low, medium and high voltage, 50 Hz or 60 Hz, networks.

General Information

• Status: Published
• Publication Date: 08-Apr-2015
• ICS: 17.220.99 - Other standards related to electricity and magnetism
• ICS: 33.200 - Telecontrol. Telemetering
• Technical Committee: TC 8 - System aspects of electrical energy supply
• Drafting Committee: WG 11 - TC 8/WG 11
• Current Stage: DELPUB - Deleted Publication
• Start Date: 29-Dec-2017
• Completion Date: 11-Feb-2020

Relations

• Revised: IEC TS 62749:2020 - Assessment of power quality - Characteristics of electricity supplied by public networks
• Effective Date: 05-Sep-2023

Standards Content (Sample)

IEC TS 62749 ®
Edition 1.0 2015-04
TECHNICAL
SPECIFICATION
colour
inside
Assessment of power quality – Characteristics of electricity supplied by public
networks
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IEC TS 62749 ®
Edition 1.0 2015-04
TECHNICAL
SPECIFICATION
colour
inside
Assessment of power quality – Characteristics of electricity supplied by public

networks
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 17.220.99 ISBN 978-2-8322-2547-9

– 2 – IEC TS 62749:2015 © IEC 2015

CONTENTS
FOREWORD . 4

INTRODUCTION . 6

1 Scope . 7

2 Normative references . 8

3 Terms and definitions . 9

4 Recommended values for power quality indices . 16

4.1 General . 16
4.2 Frequency deviation . 16
4.3 Supply voltage deviation . 16
4.3.1 General . 16
4.3.2 Low voltage systems . 16
4.3.3 Medium voltage systems. 17
4.3.4 High voltage systems . 17
4.4 Voltage unbalance . 18
4.5 Flicker. 18
4.6 Harmonic and interharmonic voltage . 18
4.6.1 General . 18
4.6.2 Low voltage systems . 18
4.6.3 Medium voltage systems. 19
4.6.4 High voltage systems . 20
4.7 Voltage dip . 21
4.8 Voltage swell . 22
4.9 Voltage interruption. 22
4.10 Mains signalling voltage . 22
4.11 Rapid voltage change . 23
4.12 Transient overvoltage . 23
4.12.1 Low voltage systems . 23
4.12.2 Medium and High voltage systems . 24
5 Objectives and methods for power quality assessment . 24
5.1 General . 24
5.2 Site power quality assessment . 24
5.2.1 General . 24

5.2.2 For continuous phenomena. 25
5.2.3 For discontinuous phenomena (single event) . 26
5.3 System aspect power quality assessment . 27
5.3.1 General . 27
5.3.2 For continuous phenomena. 27
5.3.3 For discontinuous phenomena (events) . 27
Annex A (informative) Examples of PROFILES for Power Quality Specification . 30
A.1 LV public distribution in European countries . 30
A.2 LV, MV and HV power supply system in China . 31
A.3 Example of a transmission system in Canada . 32
A.4 Examples of Profiles in Australia . 33
Annex B (informative) Example on System Aspect Continuous Disturbance Evaluation . 34
Annex C (informative） Main Impact of Poor Power Quality. 35

C.1 Harmonic distortion . 35

C.2 Voltage unbalance . 35

C.3 Voltage deviation . 36

C.4 Frequency deviation . 36

C.5 Voltage fluctuation . 36

C.6 Flicker. 36

C.7 Voltage dip (or Voltage sag) . 36

C.8 Transient overvoltages . 36

Annex D (informative) Power Quality Issues Related to Distributed Generation and

Micro-grids. 37

D.1 Voltage deviation . 37
D.2 Harmonics . 37
D.3 DG magnetic bias (DC current injection) . 37
D.4 Voltage fluctuation and flicker . 37
D.5 High frequency conducted disturbances . 38
Annex E (informative) Methods to Maintain and Improve Power Quality . 39
E.1 Voltage deviation . 39
E.2 Harmonics . 39
E.3 Flicker. 40
E.4 Unbalance . 40
E.5 Voltage dip/swell/short time interruption . 40
Annex F (informative) Relation between Power quality and EMC . 41
Bibliography . 43

Figure 1 – Signal voltages recommended values in percent of U used in public LV
N
networks (or U in public MV networks) . 23
c
Figure 2 – An example for illustrating voltage THD assessment result trends . 26
Figure 3 – An example showing information of single event assessment . 27
Figure F.1 – Application points in a LV system (example) . 42
Figure F.2 – Relation between disturbance levels (Schematic significance only) . 42

Table 1 – Classification of electromagnetic phenomena addressed by power quality
indices . 8
Table 2 – Flicker severity P recommended values . 18

lt
Table 3 – Recommended values of individual harmonic voltages at the low voltage
supply terminals for orders up to 50 given in percent of the fundamental voltage U . 19
Table 4 – Recommended values of individual harmonic voltages at the medium voltage
supply terminals for orders up to 50 given in percent of the fundamental voltage U . 20
Table 5 – Indicative values of individual harmonic voltages at the high voltage supply
terminals given in percent of the fundamental voltage U . 21
Table 6 – Site power quality assessment methods . 25
Table 7 – Example of single event assessment . 27
Table 8 – List of individual events measured at a single monitoring site . 28
Table 9 – SARFI-X indices coming out of Table 8 . 28
Table 10 – Magnitude – duration table format . 29
Table B.1 – Listing of System Power Quality Evaluation . 34

– 4 – IEC TS 62749:2015 © IEC 2015

INTERNATIONAL ELECTROTECHNICAL COMMISSION

____________
ASSESSMENT OF POWER QUALITY – CHARACTERISTICS OF

ELECTRICITY SUPPLIED BY PUBLIC NETWORKS

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising

all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To

this end and in addition to other activities, IEC publishes International
...