Electrical safety in low voltage distribution systems up to 1 000 V a.c. and 1 500 V d.c. - Equipment for testing, measuring or monitoring of protective measures - Part 8: Insulation monitoring devices for IT systems

IEC 61557-8:2014 specifies the requirements for insulation monitoring devices (IMD) which permanently monitor the insulation resistance RF to earth of unearthed a.c. IT systems, of a.c. IT systems with galvanically connected d.c. circuits having nominal voltages up to 1 000 V a.c., as well as of unearthed d.c. IT systems with voltages up to 1 500 V d.c. independent from the method of measuring. IT systems are described in IEC 60364-4-41 amongst other literature. Additional data for the selection of devices in other standards should be noted. IMDs according to this part of IEC 61557 can also be used for de-energized TT, TN and IT systems or appliances. This third edition cancels and replaces the second edition published in 2007. This edition constitutes a technical revision which includes the following significant technical changes with respect to the previous edition:
- terms and definitions have been complemented;
- abbreviations are listed and explained;
- requirements have been revised;
- mandatory and optional functions and their terminology have been adapted from IEC 61557-15;
- mechanical requirements have been added;
- information on operating instructions has been added;
- type tests and routine tests have been complemented;
- an Annex C: 'Insulation monitoring devices for photovoltaic systems (PV-IMD)' has been added; and
- an Annex D: 'Insulation monitoring function of a photovoltaic inverter (PV-IMF) or in a charge controller' has been added.
This publication is to be read in conjunction with IEC 61557-1:2007. The contents of the corrigendum of May 2016 have been included in this copy.

Sécurité électrique dans les réseaux de distribution basse tension de 1 000 V c.a. et 1 500 V c.c. - Dispositifs de contrôle, de mesure ou de surveillance de mesures de protection - Partie 8: Contrôleur permanent d'isolement pour réseaux IT

L'IEC 61557-8:2014 spécifie les exigences applicables aux contrôleurs d'isolement (CPI) destinés à surveiller en permanence, et quelle que soit la méthode de mesure, la résistance d'isolement RF par rapport à la terre de réseaux IT à courant alternatif non mis à la terre, ou de réseaux IT à courant alternatif comprenant des circuits à courant continu reliés galvaniquement dont les tensions nominales sont au plus égales à 1 000 V en courant alternatif, et de réseaux IT à courant continu non mis à la terre dont les tensions nominales sont au plus égales à 1 500 V en courant continu. Les réseaux IT sont décrits entre autres dans l'IEC 60364-4-41. Il convient de noter que, pour le choix des appareils, des indications supplémentaires sont données dans d'autres normes. Les CPI conformes à la présente partie de l'IEC 61557 peuvent également être utilisés dans des systèmes ou appareils hors tension du type TT, TN et IT. Cette troisième édition annule et remplace la deuxième édition parue en 2007. Cette édition constitue une révision technique qui inclut les modifications techniques majeures suivantes par rapport à l'édition précédente:
- les termes et définitions ont été complétés;
- énumération et explication des abréviations;
- révision des exigences;
- adaptation des fonctions obligatoires et facultatives et leur terminologie à l'IEC 61557-15;
- ajout d'exigences mécaniques;
- ajout d'informations relatives aux instructions de fonctionnement;
- les essais de type et essais individuels de série ont été complétés;
- ajout de l'Annexe C: 'Contrôleurs d'isolement pour systèmes photovoltaïques (PV-CPI)'; et
- ajout de l'Annexe D: 'Fonction de surveillance de défaut d'isolement d'un onduleur photovoltaïque (PV-IMF) ou dans un contrôleur de charge'.
Cette publication doit être lue conjointement avec la CEI 61557-1:2007. Le contenu du corrigendum de mai 2016 a été pris en considération dans cet exemplaire.

General Information

Status
Published
Publication Date
10-Dec-2014
Current Stage
PPUB - Publication issued
Completion Date
11-Dec-2014
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IEC 61557-8:2014 - Electrical safety in low voltage distribution systems up to 1 000 V a.c. and 1 500 V d.c. - Equipment for testing, measuring or monitoring of protective measures - Part 8: Insulation monitoring devices for IT systems
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IEC 61557-8
Edition 3.0 2014-12
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Electrical safety in low voltage distribution systems up to 1 000 V a.c. and
1 500 V d.c. – Equipment for testing, measuring or monitoring of protective
measures –
Part 8: Insulation monitoring devices for IT systems
Sécurité électrique dans les réseaux de distribution basse tension au plus
égale à 1 000 V c.a. et 1 500 V c.c. – Dispositifs de contrôle, de mesure ou de
surveillance de mesures de protection –
Partie 8: Contrôleur permanent d’isolement pour réseaux IT
IEC 61557-8:2014-12(en-fr)
---------------------- Page: 1 ----------------------
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---------------------- Page: 2 ----------------------
IEC 61557-8
Edition 3.0 2014-12
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Electrical safety in low voltage distribution systems up to 1 000 V a.c. and
1 500 V d.c. – Equipment for testing, measuring or monitoring of protective
measures –
Part 8: Insulation monitoring devices for IT systems
Sécurité électrique dans les réseaux de distribution basse tension au plus
égale à 1 000 V c.a. et 1 500 V c.c. – Dispositifs de contrôle, de mesure ou de
surveillance de mesures de protection –
Partie 8: Contrôleur permanent d’isolement pour réseaux IT
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX
ICS 17.220.20; 29.080.01; 29.240.01 ISBN 978-2-8322-1973-7

Warning! Make sure that you obtained this publication from an authorized distributor.

Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé.

® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale
---------------------- Page: 3 ----------------------
– 2 – IEC 61557-8:2014 © IEC 2014
CONTENTS

FOREWORD ........................................................................................................................... 6

1 Scope .............................................................................................................................. 8

2 Normative references ...................................................................................................... 8

3 Terms, definitions and abbreviations ............................................................................... 9

3.1 Terms and definitions .............................................................................................. 9

3.2 Abbreviations ........................................................................................................ 13

4 Requirements ................................................................................................................ 13

4.1 General requirements ........................................................................................... 13

4.2 Types of IMDs ....................................................................................................... 14

4.2.1 General ......................................................................................................... 14

4.2.2 Mandatory functions provided by IMDs .......................................................... 14

4.2.3 Mandatory service function provided by the IMD – Test function .................... 15

4.3 Optional functions provided by IMD ....................................................................... 15

4.3.1 General ......................................................................................................... 15

4.3.2 Local transformer monitoring warning (LTMW) ............................................... 15

4.3.3 Remote transformer monitoring warning (RTMW) ........................................... 15

4.3.4 Remote enabling and disabling command (REDC) ......................................... 16

4.4 Performance requirements .................................................................................... 16

4.4.1 Specified response value R ......................................................................... 16

4.4.2 System leakage capacitance C ..................................................................... 16

4.4.3 Relative percentage uncertainty A of the specified response value R .......... 16

4.4.4 Response time t .......................................................................................... 17

4.4.5 Measuring voltage U and measuring current I ............................................ 17

m m

4.4.6 Internal d.c. resistance R and internal impedance Z ...................................... 17

i i

4.4.7 Indication of the value of the insulation resistance R .................................... 18

4.4.8 Permanently admissible nominal voltage U ................................................... 18

4.4.9 Permanently admissible extraneous d.c. voltage U ...................................... 18

4.4.10 Supply voltage U .......................................................................................... 18

4.5 Electromagnetic compatibility (EMC) ..................................................................... 18

4.6 Safety requirements .............................................................................................. 18

4.6.1 General ......................................................................................................... 18

4.6.2 Clearances and creepage distances .............................................................. 19

4.6.3 Protection class and earth connection of an IMD ........................................... 19

4.7 Climatic environmental conditions ......................................................................... 19

4.8 Mechanical requirements ...................................................................................... 19

4.8.1 General ......................................................................................................... 19

4.8.2 Product mechanical robustness ..................................................................... 19

4.8.3 IP protection class requirements .................................................................... 20

5 Marking and operating instructions ................................................................................ 21

5.1 Marking ................................................................................................................. 21

5.2 Operating instructions ........................................................................................... 22

6 Tests ............................................................................................................................. 23

6.1 General ................................................................................................................. 23

6.2 Type tests ............................................................................................................. 23

6.2.1 General ......................................................................................................... 23

6.2.2 Test of response values ................................................................................. 23

---------------------- Page: 4 ----------------------
IEC 61557-8:2014 © IEC 2014 – 3 –

6.2.3 Test of response time t ................................................................................ 24

6.2.4 Test of peak value of the measuring voltage U ............................................. 24

6.2.5 Test of the peak value of the measuring current I ........................................ 24

6.2.6 Test of internal d.c. resistance R and internal impedance Z .......................... 25

i i

6.2.7 Test of facilities for indicating the insulation resistance R ............................. 25

6.2.8 Test of effectiveness of the test device .......................................................... 25

6.2.9 Test of permanently admissible nominal voltage U ....................................... 25

6.2.10 Test of permanently admissible extraneous d.c. voltage U ........................... 25

6.2.11 Test of supply voltage U ............................................................................... 26

6.2.12 Test of optional functions ............................................................................... 26

6.2.13 Voltage tests ................................................................................................. 26

6.2.14 Test of electromagnetic compatibility (EMC) .................................................. 26

6.2.15 Inspection of the marking and operating instructions ...................................... 26

6.2.16 Mechanical tests ............................................................................................ 26

6.3 Routine tests......................................................................................................... 27

6.3.1 General ......................................................................................................... 27

6.3.2 Test of response values ................................................................................. 27

6.3.3 Test of effectiveness of the test function ........................................................ 27

6.3.4 Test of facility for indicating the insulation resistance R ................................ 27

6.3.5 Voltage tests ................................................................................................. 27

6.3.6 Compliance with tests of 6.3 .......................................................................... 27

7 Overview of requirements and tests for IMDs ................................................................. 27

Annex A (normative) Medical insulation monitoring devices (MED-IMD) ............................... 29

A.1 Scope and object .................................................................................................. 29

A.2 Requirements ....................................................................................................... 29

A.2.1 General ......................................................................................................... 29

A.2.2 Types of MED-IMDs ....................................................................................... 29

A.2.3 Mandatory functions provided by MED-IMD ................................................... 29

A.2.4 Performance requirements ............................................................................. 30

A.2.5 Electromagnetic compatibility (EMC) ............................................................. 31

A.3 Marking and operating instructions ........................................................................ 31

A.4 Tests .................................................................................................................... 32

A.4.1 General ......................................................................................................... 32

A.4.2 Type tests ...................................................................................................... 32

A.5 Overview of requirements and tests for MED-IMDs ............................................... 32

Annex B (informative) Monitoring of overload current and over-temperature ....................... 34

B.1 Scope and object .................................................................................................. 34

B.2 Requirements ....................................................................................................... 34

B.2.1 General ......................................................................................................... 34

B.2.2 Local transformer monitoring warning (LTMW) and/or remote

transformer monitoring warning (RTMW)........................................................ 34

B.2.3 Monitoring of overload current ....................................................................... 34

B.2.4 Monitoring of over-temperature of the IT system transformer ......................... 34

B.3 Operating instructions ........................................................................................... 35

B.4 Tests .................................................................................................................... 35

B.4.1 General ......................................................................................................... 35

B.4.2 Test of overload current and over-temperature monitoring ............................. 35

Annex C (normative) Insulation monitoring devices for photovoltaic systems (PV-IMD) ........ 36

C.1 Scope and object .................................................................................................. 36

---------------------- Page: 5 ----------------------
– 4 – IEC 61557-8:2014 © IEC 2014

C.2 Requirements for PV-IMDs for PV installations ..................................................... 36

C.2.1 General ......................................................................................................... 36

C.2.2 Types of PV-IMDs .......................................................................................... 37

C.2.3 Mandatory functions provided by PV-IMDs ..................................................... 37

C.2.4 Performance requirements ............................................................................. 37

C.3 Marking and operating instructions ........................................................................ 38

C.3.1 Marking ......................................................................................................... 38

C.3.2 Operating instructions .................................................................................... 39

C.4 Tests .................................................................................................................... 39

C.4.1 General ......................................................................................................... 39

C.4.2 Additional type tests ...................................................................................... 39

C.4.3 Additional routine tests .................................................................................. 40

C.5 Overview of requirements and tests for PV-IMDs .................................................. 40

Annex D (normative) Insulation monitoring function of a photovoltaic inverter (PV-IMF)

or in a charge controller ........................................................................................................ 41

D.1 Scope and object .................................................................................................. 41

D.2 Requirements for PV-IMFs .................................................................................... 41

D.2.1 General requirements for PV-IMFs ................................................................. 41

D.2.2 Types of PV-IMFs .......................................................................................... 42

D.2.3 Mandatory functions provided by PV-IMFs ..................................................... 42

D.2.4 Performance requirements for PV-IMFs ......................................................... 43

D.2.5 Electromagnetic compatibility (EMC) ............................................................. 44

D.2.6 Safety requirements....................................................................................... 44

D.2.7 Climatic environmental conditions .................................................................. 44

D.2.8 Mechanical requirements ............................................................................... 44

D.3 Marking and operating instructions ........................................................................ 44

D.3.1 Marking ......................................................................................................... 44

D.3.2 Operating instructions .................................................................................... 44

D.4 Tests .................................................................................................................... 45

D.4.1 General ......................................................................................................... 45

D.4.2 Type tests ...................................................................................................... 45

D.4.3 Routine tests ................................................................................................. 46

D.5 Overview of requirements and tests for PV-IMF .................................................... 46

Bibliography .......................................................................................................................... 47

Figure A.1 – Pictogram for marking a MED-IMD .................................................................... 32

Figure C.1 – Dynamic reference characteristics of d.c. PV system voltage ............................ 38

Figure C.2 – Pictogram for marking a PV-IMD ....................................................................... 39

Table 1 – Abbreviations ........................................................................................................ 13

Table 2 – Product mechanical requirements .......................................................................... 20

Table 3 – Minimum IP requirements for IMDs ........................................................................ 21

Table 4 – Pictograms for marking the type of IMD ................................................................. 22

Table 5 – Reference conditions for tests in operation ............................................................ 23

Table 6 – Reference conditions for storage tests (product not powered) ............................... 23

Table 7 – Requirements and tests applicable to IMD ............................................................. 28

Table A.1 – Summary of additional requirements and tests applicable to MED-IMDs ............. 32

---------------------- Page: 6 ----------------------
IEC 61557-8:2014 © IEC 2014 – 5 –

Table A.2 – Emission test for MED-IMDs .............................................................................. 33

Table C.1 – Requirements and tests for PV-IMDs ................................................................. 40

Table D.1 – Requirements and tests for PV-IMF integrated in the inverter ............................ 46

---------------------- Page: 7 ----------------------
– 6 – IEC 61557-8:2014 © IEC 2014
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ELECTRICAL SAFETY IN LOW VOLTAGE DISTRIBUTION SYSTEMS
UP TO 1 000 V AC AND 1 500 V DC – EQUIPMENT FOR TESTING,
MEASURING OR MONITORING OF PROTECTIVE MEASURES –
Part 8: Insulation monitoring devices for IT systems
FOREWORD

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9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of

patent rights. IEC shall not be held responsible for identifying any or all such patent rights.

International Standard IEC 61557-8 has been prepared by IEC technical committee 85:

Measuring equipment for electrical and electromagnetic quantities.

This third edition cancels and replaces the second edition published in 2007. This edition

constitutes a technical revision.

This edition includes the following significant technical changes with respect to the previous

edition:
a) Terms and definitions have been complemented;
b) Abbreviations are listed and explained;
c) Requirements have been revised;
d) Mandatory and optional functions and their terminology have been adapted from
IEC 61557-15;
---------------------- Page: 8 ----------------------
IEC 61557-8:2014 © IEC 2014 – 7 –
e) Mechanical requirements have been added;
f) Information on operating instructions has been added;
g) Type tests and routine tests have been complemented;

h) An Annex C: ‘Insulation monitoring devices for photovoltaic systems (PV-IMD)’ has been

added;

i) An Annex D: ‘Insulation monitoring function of a photovoltaic inverter (PV-IMF) or in a

charge controller’ has been added.
The text of this standard is based on the following documents:
FDIS Report on voting
85/485/FDIS 85/502/RVD

Full information on the voting for the approval of this standard can be found in the report on

voting indicated in the above table.

This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

This part of IEC 61557 shall be used in conjunction with Part 1.

A list of all parts in the IEC 61557 series, published under the general title Electrical safety in

low voltage distribution systems up to 1 000 V a.c. and 1 500 V d.c. – Equipment for testing,

measuring or monitoring of protective measures, can be found on the IEC website.

The committee has decided that the contents of this publication will remain unchanged until

the stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data

related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
The contents of the corrigendum of May 2016 have been included in this copy.
...

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