IEC 61557-9:2009

Electrical safety in low voltage distribution systems up to 1000 V a.c. and 1500 V d.c. - Equipment for testing, measuring or monitoring of protective measures - Part 9: Equipment for insulation fault location in IT systems

IEC 61557-9:2009 specifies the requirements for insulation fault location systems which localize insulation faults in any part of the system in unearthed IT a.c. systems and unearthed IT a.c. systems with galvanically connected d.c. circuits having nominal voltages up to 1 000 V a.c., as well as in unearthed IT d.c. systems with voltages up to 1 500 V d.c., independent of the measuring principle. This second edition cancels and replaces the first edition published in 1999. It is a technical revision. This edition includes the following significant technical changes with respect to the previous edition:
- scope, normative references and terms and definitions complemented;
- revision of requirements, marking and operating instructions and Clause 6;
- revision of Table 1;
- addition of Annexes A, B and C.

Sécurité électrique dans les réseaux de distribution basse tension de 1000 v c.a. et 1500 v c.c. - Dispositifs de contrôle, de mesure ou de surveillance de mesures de protection - Partie 9: Dispositifs de localisation de défauts d'isolement pour réseaux IT

La CEI 61557-9:2009 définit les exigences particulières applicables aux dispositifs de localisation de défauts d'isolement qui, indépendamment du principe de mesure, peuvent localiser les défauts d'isolement des parties de réseaux IT c.a. non mis à la terre et des réseaux IT c.a. non mis à la terre comprenant des circuits à courant continu reliés galvaniquement dont les tensions nominales sont égales ou inférieures à 1 000 V c.a., ainsi que dans des réseaux IT c.c. non mis à la terre dont les tensions nominales sont égales ou inférieures à 1 500 V c.c. Cette deuxième édition annule et remplace la première édition parue en 1999. Elle constitue une révision technique. Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente:
- le domaine d'application, les références normatives et les termes et définitions ont été complétés;
- les exigences, le marquage et les instructions de fonctionnement et l'Article 6 ont été révisés;
- le Tableau 1 a été révisé;
- les Annexes A, B et C ont été ajoutées.

General Information

• Status: Published
• Publication Date: 11-Jan-2009
• ICS: 25.040.40 - Industrial process measurement and control
• Technical Committee: TC 85 - Measuring equipment for electrical and electromagnetic quantities
• Drafting Committee: WG 8 - TC 85/WG 8
• Current Stage: DELPUB - Deleted Publication
• Completion Date: 11-Dec-2014

Relations

• Revised: IEC 61557-9:2014 - 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 9: Equipment for insulation fault location in IT systems
• Effective Date: 05-Sep-2023

Standards Content (Sample)

IEC 61557-9
®
Edition 2.0 2009-01
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 9: Equipment for insulation fault location in IT systems

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 9: Dispositifs de localisation de défauts d'isolement pour réseaux IT

IEC 61557-9:2009

---------------------- Page: 1 ----------------------
THIS PUBLICATION IS COPYRIGHT PROTECTED
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---------------------- Page: 2 ----------------------
IEC 61557-9
®
Edition 2.0 2009-01
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 9: Equipment for insulation fault location in IT systems

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 9: Dispositifs de localisation de défauts d'isolement pour réseaux IT

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
S
CODE PRIX
ICS 25.040.40 ISBN 978-2-88910-536-6
® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale

---------------------- Page: 3 ----------------------
– 2 – 61557-9 © IEC:2009
CONTENTS
FOREWORD.4
1 Scope.6
2 Normative references .6
3 Terms and definitions .7
4 Requirements .8
4.1 Equipment for insulation fault location .8
4.2 Response sensitivity.8
4.3 Warning device .8
4.4 Locating current I .8
L
4.5 Locating voltage U .9
L
4.6 Indication of the insulation value .9
4.7 PE connection .9
4.8 Clearances and creepage distances .9
4.9 Electromagnetic compatibility (EMC) .9
4.10 Additional requirements.9
5 Marking and operating instructions .10
5.1 Marking .10
5.2 Operating instructions .11
6 Tests .11
6.1 Type test .12
6.1.1 Response sensitivity of the insulation fault location system .12
6.1.2 Locating current I .12
L
6.1.3 Locating voltage U .13
L
6.1.4 Warning device.13
6.1.5 Equipment for indication of the insulation value .13
6.1.6 Locating current injector .13
6.1.7 Dielectric test .13
6.1.8 Electromagnetic compatibility (EMC) .13
6.1.9 Loss of locating current sensor connection .13
6.1.10 Additional requirements .13
6.1.11 Marking and operating instructions .13
6.1.12 Record of the type test .13
6.2 Routine tests .13
6.2.1 General .13
6.2.2 Response sensitivity.13
6.2.3 Warning device.14
6.2.4 Self-test function .14
6.2.5 Dielectric test .14
6.2.6 Marking and operating instructions .14
Annex A (normative) Equipment for insulation fault location in medical locations .15
Annex B (normative) Portable equipment for insulation fault location .18
Annex C (informative) Example of an insulation fault location system and explanation of
upstream / downstream leakage capacitances .20
Bibliography.23

Figure C.1 – Example of an insulation fault location system.21

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61557-9 © IEC:2009 – 3 –
Figure C.2 – Explanation of upstream/downstream leakage capacitance.22

Table 1 – Requirements for Insulation Fault Location Systems (IFL) .10
Table A.1 – Additional requirements applicable to equipment for insulation fault location
in medical locations .17
Table A.2 – Emission test for equipment for insulation fault location in medical locations.17

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– 4 – 61557-9 © IEC:2009
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________

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 9: Equipment for insulation fault location in IT systems


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
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indispensable for the correct application of this publication.
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 61557-9 has been prepared by IEC technical committee 85:
Measuring equipment for electrical and electromagnetic quantities.
This second edition cancels and replaces the first edition published in 1999. It is a technical
revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) scope complemented;
b) normative references complemented;
c) terms and definitions of Clause 3 complemented;
d) revision of requirements;
e) revision of marking and operating instructions;
f) revision of Clause 6 “Tests”;

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61557-9 © IEC:2009 – 5 –
g) revision of Table 1;
h) addition of Annex A;
i) addition of Annex B;
j) addition of Annex C.
The text of this standard is based on the following documents:
FDIS Report on voting
85/337/FDIS 85/341/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 is to be used in conjunction with IEC 61557-1:2007.
A list of all parts of 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
maintenance result 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.

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– 6 – 61557-9 © IEC:2009
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 9: Equipment for insulation fault location in IT systems



1 Scope
This part of IEC 61557 specifies the requirements for insulation fault location systems which
localize insulation faults in any part of the system in unearthed IT a.c. systems and unearthed IT
a.c. systems with galvanically connected d.c. circuits having nominal voltages up to 1 000 V a.c.,
as well as in unearthed IT d.c. systems with voltages up to 1 500 V d.c., independent of the
measuring principle.
NOTE 1 IT systems are described in IEC 60364-4-41 amongst other literature. Additional data for a selection of
devices in other standards should be noted.
NOTE 2 Further information on insulation fault location can be found in the following standards:
IEC 60364-4-41:2005, 411.6, and IEC 60364-5-53:2001, 531.3.
2 Normative references
The following referenced documents are indispensable for the application of this document. For
dated references, only the edition cited applies. For undated references, the latest edition of the
referenced document (including any amendments) applies.
IEC 60364-4-41:2005, Low-voltage electrical installations – Part 4-41: Protection for safety –
Protection against electric shock
IEC 60664-1, Insulation coordination for equipment within low-voltage systems – Part 1:
Principles, requirements and tests
IEC 60664-3, Insulation coordination for equipment within low-voltage systems – Part 3: Use of
coating, potting or moulding for protection against pollution
IEC 60721-3-1, Classification of environmental conditions – Part 3: Classification of groups of
environmental parameters and their severities – Section 1: Storage
IEC 60721-3-2, Classification of environmental conditions – Part 3: Classification of groups of
environmental parameters and their severities – Section 2: Transportation
IEC 60721-3-3, Classification of environmental conditions – Part 3-3: Classification of groups of
environmental parameters and their severities – Stationary use at weatherprotected locations
IEC 61010-1:2001, Safety requirements for electrical equipment for measurement, control, and
laboratory use – Part 1: General requirements
IEC 61326-2-4, Electrical equipment for measurement, control and laboratory use – EMC
requirements – Part 2-4: Particular requirements – Test configurations, operational conditions
and performance criteria for insulation monitoring devices according to IEC 61557-8 and for
equipment for insulation fault location according to IEC 61557-9

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61557-9 © IEC:2009 – 7 –
IEC 61557-1:2007, 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 1:
General requirements
IEC 61557-8:2007, 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
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 61557-1, in
IEC 61557-8 and the following apply.
3.1
insulation fault location system
device or combination of devices used for insulation fault location in IT systems. The insulation
fault location system is used in addition to an insulation monitoring device. It injects a locating
current between the electrical system and earth and locates insulation faults
NOTE The requirements for insulation monitoring devices are defined in IEC 61557-8.
3.2
locating current
I
L
r.m.s. value of the current that is injected by the locating current injector during the location
process. The locating current can be generated by
– an independent locating voltage source, or
– an independent locating current source, or
– it can be driven directly from the system to be monitored
3.3
locating voltage
U
L
r.m.s. value of the voltage present at the measuring terminals of the locating current injector
during the measurement when the device has an independent locating voltage or current source
NOTE In a fault-free, de-energized system, this represents the voltage present between the terminals of the locating
device to the system to be monitored and the terminals for the connection to the PE conductor.
3.4
response sensitivity
value of the evaluating current or insulation resistance at which the evaluator responds under
specified conditions
NOTE Response sensitivity can either be a fixed threshold or a response curve.
3.5
insulation fault locator
device or part of a device for the location of the insulation fault
3.6
locating current sensor
sensor for the detection of the locating current used for the location of the insulation fault
3.7
locating current injector
device or part of a device, which function it is to inject the locating current in the IT system in
order to locate the insulation fault

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– 8 – 61557-9 © IEC:2009
3.8
passive locating current injector
locating current injector that generates the locating current directly from the system to be
monitored
3.9
active locating current injector
locating current injector that generates the locating current from a locating voltage source which
is independent from the system to be monitored
4 Requirements
The following requirements as well as those given in IEC 61557-1 shall apply.
4.1 Equipment for insulation fault location
Equipment for insulation fault location shall be capable of localizing symmetrical as well as
asymmetrical insulation faults in an IT system and to give a warning, if the insulation resistance
in a part of the installation falls below the response sensitivity.
If equipment for insulation fault location has a self-test function, the self-test shall not produce
an insulation fault to earth.
NOTE 1 See also IEC 61557-8:2007, 4.1.
NOTE 2 Insulation monitoring devices may be deactivated during the location process.
NOTE 3 Warning indication can be done by a lamp, a buzzer or by any other kind of indication.
NOTE 4 Insulation fault locating systems may have a self-test function. Checking the response sensitivity is not
necessary.
NOTE 5 Insulation fault location systems with an active locating current source may also be used for insulation fault
location in de-energized systems.
4.2 Response sensitivity
Insulation fault location systems shall be designed in such a manner that the response
sensitivity stated by the manufacturer will be met under the specified system conditions, at a
total symmetrical system leakage capacitance of 1 μF upstream the evaluating current sensor
(C = 1 μF, C = 0 μF according to Figure C.2).
Lu Ld
Information on the influence of the system leakage capacitances higher than 1 μF on the
response sensitivity as well as possible interference from the distribution system on the
insulation fault location process shall be stated by the manufacturer.
NOTE The total leakage capacitance is the sum of the leakage capacitances of all phase conductors, including the
neutral conductor to PE.
4.3 Warning device
Insulation fault location systems shall contain a visual warning device, which indicates if an
insulation fault is detected or allow connection to such a device for the indication of a fault. If
externally connectable audible signalling devices are provided, they may be fitted with a
resetting facility. In this case, after clearing a fault or resetting the device, the audible signal
shall sound if a new fault occurs.
4.4 Locating current I
L
The maximum locating current I shall be limited to 500 mA, r.m.s., to ensure that the locating
L
current does not produce touch voltages above the conventional voltage limit (50 V a.c., 120 V

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61557-9 © IEC:2009 – 9 –
d.c.) under the first fault in the distribution system. The locating current shall not increase above
500 mA, r.m.s., under foreseeable component failures in the locating current injector. When the
locating current is adjustable, unintentional changes of the setting shall be prevented by suitable
means.
4.5 Locating voltage U
L
If an active locating voltage or locating current is used, the locating voltage U shall be equal or
L
below 50 V a.c. or 120 V d.c. (see IEC 60364-4-41) under no load conditions.
If an active locating voltage U above 50 V a.c. or 120 V d.c. is used the locating current shall not
L
exceed 3,5 mA a.c., (r.m.s.) or 10 mA d.c. through a pure resistance of 2 000 Ω.
4.6 Indication of the insulation value
When insulation fault location systems include means for the indication of the insulation value,
the uncertainty of the indicated value shall be stated by the manufacturer.
4.7 PE connection
Contrary to IEC 61557-1, the PE connection of insulation fault location systems (locating current
injector) is a measuring connection and shall be treated as functional earth connection (FE). If
the insulation fault location system has accessible parts which are earthed for protective
purposes, these connections shall be treated as protective connections (PE).
4.8 Clearances and creepage distances
Insulation fault location systems shall have minimum clearances and creepage distances in
accordance with IEC 60664-1 and IEC 60664-3, or only IEC 61010-1. Clearances and creepage
distances shall be selected in accordance with
– overvoltage category III,
– pollution degree 2, and
– pollution degree 1 for circuits inside the housing which are coated according to IEC 60664-3.
NOTE For accessible parts on the outside of the housing, creepage distances of pollution degree 3 are
recommended to withstand higher environmental requirements.
Where different voltages are used in one device, clearances and creepage distances shall be
designed for the highest voltage.
4.9 Electromagnetic compatibility (EMC)
Insulation fault location systems shall comply with the requirements for electromagnetic
compatibility (EMC) in accordance with IEC 61326-2-4.
4.10 Additional requirements
Additional requirements for insulation fault location systems are listed in Table 1.

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– 10 – 61557-9 © IEC:2009
Table 1 – Requirements for Insulation Fault Location Systems (IFL)
Requirements for type test Requirements for routine tests
Response sensitivity According to 6.1.1 According to 6.2.2
Locating current I According to 6.1.2 Not applicable
L
Locating voltage U According to 6.1.3 Not applicable
L
Warning device According to 6.1.4 According to 6.2.3
Relative uncertainty of the According to 6.1.5 Not applicable
a
indicated insulation value
Locating current injector According to 6.1.6 According to 6.2.4
Dielectric test According to 6.1.7 According to 6.2.5
Electromagnetic compatibility According to 6.1.8 Not applicable
Marking and operating instructions According to 6.1.11 According to 6.2.6
Minimum permanently admissible Not applicable
1,15 × U

n
b
nominal voltage
of the highest nominal voltage U
n
Climatic environmental conditions – Operation: class 3k5
c
(IEC 60721-3-3: -5 °C to +45 °C)
– Transport: class 2k3
(IEC 60721-3-2: -25 °C to +70 °C)
– Storage: class 1k4 (IEC 60721-3-1:
-25 °C to +55 °C)
a
The relative uncertainty is evaluated under the conditions of 4.5 and in addition:
– operation temperatures between –5 °C and +45 °C;
– at the voltages U and U and the leakage capacitances C stated by the manufacturer in the operating
s n e
instructions.
b
U is the phase-to-phase voltage in a three-phase system or the phase-to-neutral voltage in a one-phase system.
n
c
 Except condensation and the formation of ice.

5 Marking and operating instructions
5.1 Marking
In addition to the marking in accordance with IEC 61557-1, the following information shall be
provided on insulation fault location systems, if applicable.
5.1.1 Type of device as well as mark of origin or name of the manufacturer.
5.1.2 Type of IT system to be monitored (if the insulation fault location system is designed for
a specific type of IT system).
5.1.3 Wiring diagram or number of the wiring diagram or number of the operating instructions.
5.1.4 Nominal system voltage
...