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
• Start Date: 11-Dec-2014
• Completion Date: 26-Oct-2025

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
• Revises: IEC 61557-9:1999 - 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

Overview

IEC 61557-9:2009 is an international standard focused on ensuring electrical safety in low-voltage distribution systems up to 1000 V AC and 1500 V DC. This part of the IEC 61557 series specifically addresses equipment for insulation fault location in unearthed IT systems. It provides detailed requirements for devices that test, measure, or monitor protective measures by accurately locating insulation faults within IT systems-both AC and DC configurations.

The standard applies to insulation fault location systems in unearthed IT AC systems and unearthed IT DC systems with nominal voltages reaching up to 1000 V AC and 1500 V DC, respectively. It covers devices regardless of the measuring principle employed and aims to enhance safety by facilitating fast and reliable detection of insulation faults.

This 2009 edition is a technical revision of the original 1999 version, featuring expanded scope, updated terms and definitions, refined requirements, improved marking and operating instructions, and additional annexes addressing various application scenarios.

Key Topics

• Insulation Fault Location Systems (IFL): Defines the operational and technical requirements for locating insulation faults in IT systems.
• Response Sensitivity and Warning Devices: Specifies minimum performance criteria, including sensitivity levels and fault indication capabilities.
• Locating Currents and Voltages: Details parameters for the current and voltage used during insulation fault localization to ensure safety and effectiveness.
• Marking and Operating Instructions: Requirements for clear and comprehensive product labeling and user guidance to ensure proper use and compliance.
• Testing and Compliance: Describes mandatory type and routine tests, including sensitivity verification, dielectric and electromagnetic compatibility (EMC) testing.
• Additional Requirements: Includes provisions for clearance, creepage distances, protective earth (PE) connections, and fault location in specialized environments such as medical locations.
• Normative References: Integrates essential related standards for installation, safety, insulation coordination, and EMC requirements.

Applications

IEC 61557-9:2009 is crucial for manufacturers, installers, and maintenance personnel working with unearthed IT low-voltage electrical distribution systems. Its practical applications include:

• Fault Diagnosis in IT Electrical Networks: Enables rapid localization of insulation faults to prevent system failures or hazardous conditions.
• Safety Compliance: Assists organizations in meeting regulatory safety requirements for low-voltage electrical equipment and installations.
• Medical Sector: Annex A specifically addresses insulation fault localization equipment used in medical facilities where electrical safety is paramount.
• Portable Diagnostic Devices: Annex B covers portable equipment requirements, expanding usability for on-site troubleshooting.
• System Reliability Enhancement: Supports continuous monitoring and preventive maintenance by identifying insulation degradation early.

The standard ensures that insulation fault location equipment used in industrial, commercial, and healthcare settings provides consistent, reliable, and safe fault detection, helping to avoid electric shock risks and system downtime.

Related Standards

IEC 61557-9:2009 should be used in conjunction with other international standards to achieve comprehensive protection and measurement solutions in low-voltage electrical systems:

• IEC 61557-1:2007 – General requirements for equipment used to test, measure or monitor protective measures.
• IEC 60364-4-41:2005 – Protection for safety: Protection against electric shock in low-voltage electrical installations.
• IEC 60664-1 and IEC 60664-3 – Standards on insulation coordination and pollution protection.
• IEC 61010-1:2001 – Safety requirements for electrical equipment for measurement and laboratory use.
• IEC 61326-2-4 – EMC requirements specifically for measurement equipment.
• IEC 60364-5-53 – Additional guidance on insulation fault location in electrical systems.

By integrating these standards, professionals can ensure that insulation fault location systems are robust, compliant, and optimized for safe operation in a variety of industrial and clinical environments.

---

Keywords: IEC 61557-9, insulation fault location, IT systems, low voltage distribution, electrical safety, unearthed systems, insulation monitoring, fault detection equipment, IEC standards, electrical testing equipment, protective measures, medical electrical safety, low voltage fault location.

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

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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
– 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

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

– 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
co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and in
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6) All users should ensure that they have the latest edition of this publication.
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
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”;

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.
– 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

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

– 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

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.

– 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 U or range of the nominal voltage.
n
5.1.5 Nominal value of the rated supply voltage U or range of the rated supply voltage.
S
5.1.6 Nominal frequency of the rated supply voltage U and the nominal voltage U or working
S n
range of frequencies for the rated supply voltage or nominal voltage.
5.1.7 Response sensitivity or range of response sensitivity under specified conditions
(see 4.2).
61557-9 © IEC:2009 – 11 –
5.1.8 The serial number, the year of manufacture or the type designation mandatory on the
outside and, if necessary, on the inside.
5.1.9 All data of 5.1 shall be indelibly marked on the insulation fault location system.
5.2 Operating instructions
The operating instructions shall state the following in addition to the statements given in
IEC 61557-1.
5.2.1 Maximum value of the locating voltage U in case when it is independent from the voltage
L
in the system to be monitored.
5.2.2 Maximum value of the locating current I in cases where it is independent from the
L
voltage in the system to be monitored.
5.2.3 Response sensitivity.
5.2.4 Technical data of the interface for the connection of an external warning device, including
rated voltage and rated current, rated insulation voltage and explanation of the interface
function.
NOTE The information for contact circuits should be in accordance with IEC 61810-2 or IEC 60947-5-1 and
IEC 60947-5-4.
5.2.5 Wiring diagram when this is not marked on the device in accordance with 5.1.3.
5.2.6 Information on the influence of system leakage capacitances, of the system voltage and
of the type of distribution system on the response sensitivity.
5.2.7 Locating voltage according to 6.1.7 and conformity to the relevant EMC standards.
5.2.8 Functional description of the insulation fault location system.
5.2.9 An indication that the system to be monitored including any connected appliances might
be influenced by insulation fault location systems, for example influence on residual current
devices (RCDs).
5.2.10 An indication that insulation monitoring devices may be influenced by insulation fault
location systems, if applicable.
5.2.11 If the insulation monitoring device is deactivated during the fault indication, it shall be
explained in the operating instructions.
5.2.12 The maximum operating uncertainty for the response sensitivity under specified
conditions.
5.2.13 The maximum operating uncertainty for the indication of the insulation value, if
applicable.
6 Tests
The following tests in addition to those required according to IEC 61557-1 shall be executed
(see also Table 1).
– 12 – 61557-9 © IEC:2009
6.1 Type test
The type tests shall be carried out according to 6.1.1 to 6.1.12.
6.1.1 Response sensitivity of the insulation fault location system
The response sensitivity shall be tested at the lowest and at the highest value of the nominal
system voltage U and of the rated supply voltage U and under the conditions of 4.2.
n S
For this test, the insulation resistance shall be simulated as follows:
– single pole (from one phase of U );
n
– symmetrically (same resistor from all phases of U ).
n
The measuring device used for testing shall be able to accommodate slow continuous or
fine-step changes of the insulation resistance as well as a connection of system leakage
capacitances according to 4.2. Capacitors with an insulation resistance of at least 100 MΩ and
a tolerance limit of ±10 % maximum shall be used for simulating system leakage capacitances.
During testing, the insulation faults are simulated by externally connected test resistors. The
response sensitivity shall be determined at the lower and the upper value of the voltage of the
system to be monitored by reducing the test resistances slowly. The response sensitivity shall
be determined with symmetrical and single pole test resistances. If the measuring principle
depends on the magnitude of the system leakage capacitance, the specified response sensitivity
shall be tested by connecting capacitors step by step.
When the insulation fault location system is provided with adjustable response sensitivity, the
tests shall be performed at the lowest and at the highest value for a value which is adjustable
continuously and for all values with fixed selectable response sensitivities.
The tests shall be performed under the climatic environmental conditions of Table 1.
The response sensitivity shall be compared with the values stated by the manufacturer.
6.1.2 Locating current I
L
Compliance with the requirements in 4.4 and 4.5 shall be verified.
The locating current shall be measured in an IT system with no leakage capacitance and with an
insulation resistance >100 MΩ as follows:
– If the location current is driven directly from the system to be monitored or if an independent
locating voltage source is used with a locating voltage equal or below 50 V a.c or 120 V d.c:
– set the voltage of the IT system to the maximum nominal system voltage of the device;
– connect an Ampere Meter (mA meter) between one phase conductor and the PE
conductor and measure the r.m.s value of the locating current. The measured value shall
not be higher than the value stated by the manufacturer in the operating instructions and
shall not be higher than 500 mA.
– If an independent locating voltage source is used with a locating voltage above 50 V a.c. or
120 V d.c.:
– connect a resistor of 2 kΩ in series with an Ampere Meter (mA meter) between the
interconnected system terminals and the earth terminal and measure the r.m.s. current of
the locating current. The measured value shall not be higher than 3,5 mA a.c. (r.m.s.) or
10 mA d.c.
61557-9 © IEC:2009 – 13 –
6.1.3 Locating voltage U
L
Compliance with 4.5 shall be verified, if applicable. The locating voltage is measured using a
voltmeter, which is connected between the connections of the locating current injector to the
system to be monitored and the PE conductor under no load condition.
6.1.4 Warning device
Compliance with the requirements given in 4.3 shall be verified.
6.1.5 Equipment for indication of the insulation value
Compliance with 4.6 shall be verified.
6.1.6 Locating current injector
Compliance with 4.4 shall be verified.
6.1.7 Dielectric test
Insulation fault detection systems shall be tested in accordance with IEC 61010-1.
6.1.8 Electromagnetic compatibility (EMC)
The electromagnetic compatibility shall be tested in accordance with IEC 61326-2-4.
6.1.9 Loss of locating current sensor connection
If provided, it shall be verified that loss of the connection to the locating current sensor is
indicated according to 4.1.
For this test, interruption and short circuit of the connection shall be simulated.
6.1.10 Additional requirements
Compliance with the requirements given in 4.6, 4.7, 4.8 and 4.10 shall be verified.
6.1.11 Marking and operating instructions
Compliance with the requirements given in 5.1 and 5.2 shall be verified by visual inspection.
6.1.12 Record of the type test
The results of the type test shall be documented.
6.2 Routine tests
6.2.1 General
Routine tests shall be carried out according to Table 1.
NOTE Engineering and statistical analyses may show that routine tests on each insulation fault location system may
not always be required, in which case sampling tests may be made instead. These tests should be carried out either
during the manufacturing process or at the end.
6.2.2 Response sensitivity
The response sensitivity shall be verified for compliance on each insulation fault location system.
The routine test shall be carried out in accordance with 6.1.1 and at the specified conditions of
4.2. In this test the following conditions apply:

– 14 – 61557-9 © IEC:2009
– room temperature (23 ± 3) °C at 1,0 times U and 1,0 times U or the lowest and highest rated
n S
value of U and U for a device with several rated voltages or with a range of rated voltages;

n S
– at a minimum of three settings including the minimum, the maximum and at a point in the
centre of the setting of the response sensitivity for devices with continuously adjustable
response sensitivity;
– at each step for devices with stepwise adjustment of the response sensitivity.
During this test, the limits shall be reduced to such a degree that the conditions in Table 1 are
met.
6.2.3 Warning device
Compliance with the requirements given in 4.3 shall be verified.
6.2.4 Self-test function
Compliance with 4.1 shall be verified.
6.2.5 Dielectric test
The dielectric test shall be performed in accordance with Annex F of IEC 61010-1:2001.
6.2.6 Marking and operating instructions
Compliance with 5.1 shall be verified by visual inspection.

61557-9 © IEC:2009 – 15 –
Annex A
(normative)
Equipment for insulation fault location in medical locations

A.1 Scope and object
This Annex A specifies the additional requirements for equipment for insulation fault location
which is used in unearthed IT a.c. systems of GROUP 2 medical locations in accordance with
IEC 60364-7-710.
NOTE The information and requirements specified here replace or supplement the corresponding clauses and
subclauses of the main text of this standard, as indicated.
A.2 Normative references
The following referenced documents are indispensable for the application of Annex A. For dated
references, only the edition cited applies. For undated references, the latest edition of the
referenced document (including any amendments) applies.
CISPR 11, Industrial, scientific and medical (ISM) radio-frequency equipment – Electromagnetic
disturbance characteristics – Limits and methods of measurement
IEC 60364-7-710:2002, Electrical installations of buildings – Part 7-710: Requirements for
special installations or locations – Medical locations
A.3 Terms and definitions
For the purposes of this Annex, the terms and definitions given in Clause 3 of this standard, as
well as the following apply.
A.3.1
equipment for insulation fault location in medical locations
specific insulation fault location equipment dedicated to locating insulation faults in IT systems
of GROUP 2 medical location. These devices should comply with Annex A
A.3.2
response time
t
al
time required by insulation fault location equipment to respond under the conditions of A.4.5

A.3.3
GROUP 2 medical locations
medical locations, where applied parts are intended to be used in applications such as
intracardiac procedures, operating theatres and vital treatment, where discontinuity (failure) of
the supply can cause danger to life
NOTE An intracardiac procedure is a procedure, whereby an electrical conductor is placed within the cardiac zone of
a patient or is likely to come into contact with the heart, such conductor being accessible outside the patient's body.
In this context, an electrical conductor includes insulated wires, such as cardiac pacing electrodes or intracardiac
ECG-electrodes, or insulated tubes filled with conducting fluids.
[IEC 60364-7-710, 710.3.7]
– 16 – 61557-9 © IEC:2009
A.4 Requirements
The following requirements or modifications as well as those given in Clause 4 of this standard
shall apply.
A.4.1 Response sensitivity
The minimum response sensitivity shall be 50 kΩ or U / 50 kΩ at a total upstream leakage

n
capacitance (sum of the leakage capacitances of all phase conductors to ground) of 1 μF.
A.4.2 Locating current I
L
The locating current shall be limited to 1 mA r.m.s.
A.4.3 Locating voltage U
L
If an active locating voltage or locating current is used, the locating voltage U shall be below 25

L
V a.c. r.m.s. or d.c. according to IEC 60364-7-710.
A.4.4 Electromagnetic compatibility (EMC)
Equipment for insulation fault location in medical locations shall comply with IEC 61326-2-4 and
in addition with CISPR 11.
A.4.5 Response time t
al
The response time under the conditions of A.4.2 shall be stated by the manufacturer.
A.4.6 Indication
An indication shall take place that indicates in which section of the installation the insulation fault
has been detected.
A.5 Marking and operating instructions
Clause 5 of this standard applies.
A.6 Tests
Clause 6 of this standard applies. Additionally the requirements of A.4 shall be considered.
A.6.1 Type tests
The response time t shall be tested at the nominal system voltage and at a total leakage

al
capacitance of 1 μF symmetrically distributed from all phase conductors upstream the
evaluating current sensor by suddenly reducing the insulation resistance from nearly infinity to
25 kΩ. Table A.1 shows additional requirements applicable to equipment for insulation fault
location in medical locations. Table A.2 shows emission test for equipment for insulation fault
location in medical locations.

61557-9 © IEC:2009 – 17 –
Table A.1 – Additional requirements applicable to equipment
for insulation fault location in medical locations
Requirements for type tests Requirements for routine tests
Response sensitivity According to 6.1.1 and A.4.1 According to 6.2.2 and A.4.1
Locating current I According to 6.1.2 and A.4.2 Not applicable
L
Locating voltage U According to 6.1.3 and A.4.3 Not applicable
L
Electromagnetic compatibility According to 6.1.8 and A.4.4 (Table A.2) Not applicable

Table A.2 – Emission test for equipment for insulation
fault location in medical locations
Test No. Access Test Specification Class Comment Basic
Standard
Complete Radiated 30 MHz to 230 MHz B At rated CISPR 11
1 device disturbance 230 MHz to 1 000 MHz voltage
emission
Supply Conducted 150 kHz to 30 MHz B At rated CISPR 11
connections disturbance voltage
and main emission
connections
– 18 – 61557-9 © IEC:2009
Annex B
(normative)
Portable equipment for insulation fault location

B.1 Scope and object
This Annex B specifies the additional requirements for portable equipment for insulation fault
location which is used in unearthed IT systems.
This portable equipment can be used instead or in combination with fixed equipment for
insulation fault location.
NOTE The information and requirements specified here replace or supplement the corresponding clauses and
subclauses of the main text of this standard, as indicated.
B.2 Normative references
The following referenced documents are indispensable for the application of this Annex. For
dated references, only the edition cited applies. For undated references, the latest edition of the
referenced document (including
...