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 11: Effectiveness of residual current monitors (RCM) in TT, TN and IT systems

IEC 61557-11:2020 is available as IEC 61557-11:2020 RLV which contains the International Standard and its Redline version, showing all changes of the technical content compared to the previous edition.IEC 61557-11:2020 specifies the requirements for test equipment applied to the testing of the effectiveness of residual current monitors (RCM) that are already installed in distribution systems. This test equipment can be used in any kind of network, such as a TN, TT or IT system. The test equipment can also be used for testing directionally discriminating residual current monitors (RCM) in IT systems. It is not the purpose of this document to verify the residual current monitors (RCM) according to their product standards. IEC 61557-11:2020 cancels and replaces the first edition published in 2009. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition:
a) document title modified to include all types of RCM;
b) terms aligned with IEC 60050;
c) addition of requirements for testing new types of RCM;
d) moving of requirements for RCM Type B from former Annex A to main body text;
e) alignment of the structure with that of the whole IEC 61557 series.

Sécurité électrique dans les réseaux de distribution basse tension au plus égale à 1000 V c.a. et 1500 V c.c. - Dispositifs de contrôle, de mesure ou de surveillance de mesures de protection - Partie 11: Efficacité des contrôleurs d'isolement à courant différentiel résiduel (RCM) dans les réseaux TT, TN et IT

IEC 61557-11:2020 est disponible sous forme de IEC 61557-11:2020 RLV qui contient la Norme internationale et sa version Redline, illustrant les modifications du contenu technique depuis l'édition précédente.L'IEC 61557-11:2020 spécifie les exigences relatives au matériel d'essai appliqué à l'essai de l'efficacité des contrôleurs d'isolement à courant différentiel résiduel (RCM - Residual Current Monitors) déjà installés dans les réseaux de distribution. Ce matériel d'essai peut être utilisé dans n'importe quel type de réseau tel qu'un réseau TN, TT ou IT. Le matériel d'essai peut également être utilisé pour l'essai des contrôleurs d'isolement à courant différentiel résiduel (RCM) sélectifs en direction dans des réseaux IT. Le présent document n’a pas pour objet de vérifier les contrôleurs d'isolement à courant différentiel résiduel (RCM) selon leurs normes de produit. L'IEC 61557-11:2020 annule et remplace la première édition parue en 2009. Cette édition constitue une révision technique. Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente:
a) le titre du présent document a été modifié pour inclure tous les types de RCM;
b) termes alignés avec l'IEC 60050;
c) ajout des exigences pour les essais de nouveaux types de RCM;
d) déplacement des exigences pour les RCM de type B de l'ancienne Annexe A dans le texte normatif;
e) alignement de la structure sur celle de l'ensemble de la série IEC 61557.

General Information

Status
Published
Publication Date
22-Jun-2020
Current Stage
PPUB - Publication issued
Completion Date
23-Jun-2020
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IEC 61557-11
Edition 2.0 2020-06
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
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 11: Effectiveness of residual current monitors (RCM) in TT, TN and IT
systems
Sécurite 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 11: Efficacité des contrôleurs d'isolement à courant différentiel résiduel

(RCM) dans les réseaux TT, TN et IT
IEC 61557-11:2020-06(en-fr)
---------------------- Page: 1 ----------------------
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---------------------- Page: 2 ----------------------
IEC 61557-11
Edition 2.0 2020-06
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
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 11: Effectiveness of residual current monitors (RCM) in TT, TN and IT
systems
Sécurite 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 11: Efficacité des contrôleurs d'isolement à courant différentiel résiduel

(RCM) dans les réseaux TT, TN et IT
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 17.220.20; 29.080.01; 29.240.01 ISBN 978-2-8322-8496-4

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 61557-11:2020 © IEC 2020
CONTENTS

FOREWORD ........................................................................................................................... 3

1 Scope .............................................................................................................................. 5

2 Normative references ...................................................................................................... 5

3 Terms and definitions ...................................................................................................... 5

4 Requirements .................................................................................................................. 7

4.1 General ................................................................................................................... 7

4.2 Functions ................................................................................................................ 7

4.2.1 Operating test .................................................................................................. 7

4.2.2 Non-operating test ......................................................................................... 10

4.2.3 Test of actuating time .................................................................................... 10

4.3 Fault voltages exceeding U ................................................................................. 10

4.4 Overvoltage .......................................................................................................... 10

5 Marking and operating instructions ................................................................................ 11

5.1 Markings ............................................................................................................... 11

5.2 Operating instructions ........................................................................................... 11

5.2.1 General ......................................................................................................... 11

5.2.2 Information .................................................................................................... 11

5.2.3 Warnings ....................................................................................................... 11

6 Tests ............................................................................................................................. 11

6.1 General ................................................................................................................. 11

6.2 Operating uncertainty ............................................................................................ 12

6.3 Test of protection against high fault voltages ........................................................ 13

6.4 Test of overvoltage ............................................................................................... 13

Bibliography .......................................................................................................................... 14

Figure 1 – Maximum step size of increasing smooth direct test current (I ) ............................ 8

Figure 2 – Maximum gradient of linearly increasing smooth direct test current (I ) ................. 9

Figure 3 – Example for linearly increasing smooth direct test current (I ): I = 30 mA .......... 9

T ∆n

Table 1 – Calculation of operating uncertainty ...................................................................... 13

---------------------- Page: 4 ----------------------
IEC 61557-11:2020 © IEC 2020 – 3 –
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 11: Effectiveness of residual current
monitors (RCM) in TT, TN and 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

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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 61557-11 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 2009. This edition

constitutes a technical revision.

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

edition:
a) document title modified to include all types of RCM;
b) terms aligned with IEC 60050;
c) addition of requirements for testing new types of RCM;
d) moving of requirements for RCM Type B from former Annex A to main body text;
---------------------- Page: 5 ----------------------
– 4 – IEC 61557-11:2020 © IEC 2020
e) alignment of the structure with that of the whole IEC 61557 series.
The text of this International Standard is based on the following documents:
FDIS Report on voting
85/720/FDIS 85/722/RVD

Full information on the voting for the approval of this International Standard can be found in the

report on voting indicated in the above table.

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

This International Standard is to be used in conjunction with IEC 61557-1:2019.

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 AC and 1 500 V DC – 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 document will remain unchanged until the

stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to

the specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
---------------------- Page: 6 ----------------------
IEC 61557-11:2020 © IEC 2020 – 5 –
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 11: Effectiveness of residual current
monitors (RCM) in TT, TN and IT systems
1 Scope

This part of IEC 61557 specifies the requirements for test equipment applied to the testing of

the effectiveness of residual current monitors (RCM) that are already installed in distribution

systems.

This test equipment can be used in any kind of network, such as a TN, TT or IT system. The

test equipment can also be used for testing directionally discriminating residual current monitors

(RCM) in IT systems.

It is not the purpose of this document to verify the residual current monitors (RCM) according

to their product standards.
2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements 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 61010-1:2010, Safety requirements for electrical equipment for measurement, control, and

laboratory use – Part 1: General requirements

IEC 61557-1:2019, 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 1:

General requirements

IEC 61557-6, 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 6:

Effectiveness of residual current devices (RCD) in TT, TN and IT systems
3 Terms and definitions

For the purposes of this document, the terms and definitions given in IEC 61557-1, IEC 61557-

6, and the following apply.

ISO and IEC maintain terminological databases for use in standardization at the following

addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
---------------------- Page: 7 ----------------------
– 6 – IEC 61557-11:2020 © IEC 2020
3.1
earth fault current
current flowing to earth due to an insulation fault
[SOURCE: IEC 60050-442:1998, 442-01-23]
3.2
test current

current superimposed by the test equipment for testing the effectiveness of the RCM

3.3
residual current

RMS value of the vector sum of the currents flowing through the main circuit of the residual

current device due to an insulation fault

[SOURCE: IEC 60050-442:2019, 442-05-19, modified – The wording "instantaneous values"

has been deleted from the definition and "due to an insulation fault" has been added.]

3.4
rated residual operating current

value of residual operating current assigned to the RCM by the manufacturer at which the RCM

operates under specified conditions
3.5
residual operating current

value of residual current which causes the residual current monitoring device to operate under

specified conditions

[SOURCE: IEC 60050-442:2019, 442-05-20, modified: "residual current device" has been

replaced with "residual current monitoring device" and symbol "I " has been replaced with

"I ".]
3.6
residual non-operating current

value of residual current at and below which the RCM does not operate under specified

conditions

[SOURCE: IEC 60050-442:2019, 442-05-21, modified – "residual current device" has been

replaced with "RCM" and the symbol has been omitted.]
3.7
actuating time

time taken for an RCM to change from the non-alarm state to the alarm state in response to the

sudden appearance of a residual current which exceeds the preset level
[SOURCE: IEC 62020-1:2020, 3.1.6, modified – The symbol has been added.]
---------------------- Page: 8 ----------------------
IEC 61557-11:2020 © IEC 2020 – 7 –
3.8
residual current monitor
RCM

device or association of devices which monitors the residual current in an electrical installation,

and which activates an alarm when the residual current exceeds the operating value of the

device
[SOURCE: IEC 62020-1:2020, 3.1.1]
3.9
RCM Type A

type of RCM for which monitoring is ensured for residual sinusoidal alternating currents and

residual pulsating direct currents, whether suddenly applied or slowly rising

[SOURCE: IEC 62020-1:2020, 5.2.6.2, modified – The words "initiating an alarm" have been

replaced with "monitoring".]
3.10
RCM Type B

type of RCM for which monitoring is ensured for residual sinusoidal alternating currents, with

residual pulsating direct currents and smooth residual direct currents independent of polarity,

whether suddenly applied or slowly rising
Note 1 to entry: RCM Type B are described in IEC 62020-1:2020, 5.2.6.4.
3.11
directionally discriminating RCM

type of RCM having the ability to discriminate between supply side and load side residual

currents of the monitored lines, as declared by the manufacturer
Note 1 to entry: Directionally discriminating RCM are described in IEC 62020-1.
[SOURCE: IEC 62020-1:2020, 3.1.10]
4 Requirements
4.1 General

In addition to the requirements of IEC 61557-1:2019, Clause 4, the requirements of Clause 4 of

this document shall apply.
4.2 Functions
4.2.1 Operating test

The testing equipment shall be capable of verifying that the residual operating current of an

RCM Type A tested with an AC test current is less than or equal to the value of the rated residual

operating current.

Testing of an RCM Type A shall be conducted with a calibrated AC current suddenly applied at

a zero crossing.

The tests shall be carried out with a sinusoidal, or mains-derived quasi-sinusoidal, test current.

If the test equipment is capable of producing half-wave test currents, testing of an RCM Type A

may be carried out alternatively with half-wave test currents and/or AC current with

superimposed ±6 mA DC.
---------------------- Page: 9 ----------------------
– 8 – IEC 61557-11:2020 © IEC 2020

In the case of pulsed DC current, the test equipment shall be capable of testing in both

polarities.

When testing an RCM Type B with a DC test current, it shall be verified that the residual

operating current is less than or equal to 2 times the value of the rated residual operating

current.

Testing of an RCM Type B shall be conducted separately with a suddenly applied, calibrated

AC current and a linearly increasing smooth direct current.
The slope of the linear increase shall not be greater than 2 times I / 5 s.

If the slope of the linear increase is simulated by a stepwise or linearly increasing test current;

the increase shall not be greater than 2 times I / 30 (see Figure 1 to Figure 3).

In both cases, the starting current shall be less than 0,2 times I .

The operating uncertainty of the increasing test current I shall not exceed ±10 % of the rated

residual operating current I .

The operating uncertainty of the calibrated test current I shall not exceed 0 % to +10 % of the

rated residual operating current I .

The test period shall be adapted to the set actuating time of the RCM and it shall be possible

to extend the test period up to 10 s.
Figure 1 – Maximum step size of increasing smooth direct test current (I
---------------------- Page: 10 ----------------------
IEC 61557-11:2020 © IEC 2020 – 9 –

Figure 2 – Maximum gradient of linearly increasing smooth direct test current (I )

Figure 3 – Example for linearly increasing smooth direct test current (I ): I = 30 mA

T ∆n
Key (for Figure 1 to Figure 3)
t time
I rated residual operating current
I smooth direct test current

∆I slope of the linear increasing test current or steps of stepwise rising test current

∆t time for one step for linearly increasing test current or time for steepness of continuous rising test current

A slow continuous or stepwise increase of the DC test current is required to prevent the AC

sensitive part of the RCM Type B from operating during the DC test.
Example for ∆I = 2 mA: ≥ 167 ms
Example for ∆I = 0,5 mA: ≥ 42 ms
NOTE 1 Existing leakage currents downstream can influence the verification.
---------------------- Page: 11 ----------------------
– 10 – IEC 61557-11:2020 © IEC 2020

NOTE 2 The actual rise time depends on the system capacitance and the resistive load of the test equipment.

NOTE 3 Smooth DC test current refers to direct current with AC ripple up to 10 % (peak to peak).

4.2.2 Non-operating test

When a test at 50 % or less of the rated residual operating current is used to test the reliability

of the RCM is included, the minimum test period shall be 10 s. The alarm shall not be activated.

When a non-operating test at 50 % or less of the rated residual operating current is included,

the operating uncertainty of the calibrated test current shall not exceed 0 % to −10 % of the

specified non-operating test current.
NOTE Existing leakage currents downstream can influence the verification.
4.2.3 Test of actuating time

If the set actuating time of the RCM is being tested with the test equipment, the setting of the

test period on the test device shall have a resolution of minimum 0,5 s ranging up to 10 s. The

setting uncertainty shall not exceed 0 % to −10 % of the set value. The test shall solely be

performed with calibrated AC test current.

Other methods for the acquisition of the actuating time via optical recognition or interfacing are

permissible.

NOTE The general function of RCMs is not to disconnect the power supply when a residual current above the value

of the rated residual operating current occurs. The RCM indicates the increase of the residual current above the

residual operating current with a signalling device, for example a lamp, buzzer, contact relay or interface-signal.

Thus, the response time can only be tested via the visual or additional electrical detection of this signal.

According to IEC 62020-1, the actuating time of the RCM may only amount to a maximum of

10 s. The response time shall be specified by the manufacturer or shall be adjustable on the

device.

If the RCM is being used for the purpose of disconnection, the tests covered by IEC 61557-6

shall apply.
4.3 Fault voltages exceeding U

Prevention of danger due to fault voltages exceeding U within the system under test shall be

ensured during the use of the test equipment. This can be achieved as follows:

– automatic disconnection in accordance with IEC 61010-1:2010, Figure 1, if the residual

voltage is above 50 V AC or 120 V DC;

– application of test current I , gradually or permanently adjustable, where the test starts with

a maximum current of 3,5 mA AC or 15 mA DC in accordance with IEC 61010-1:2010,

6.3.2 b), including parallel test circuits, is permitted. The possibility to change the test

current I without generating a dangerous fault voltage shall be clearly identifiable, for

instance on a voltmeter;
– in special locations, the touch voltage limit is 25 V AC or 60 V DC;

– the operating uncertainty for the detection of the fault voltage shall not exceed 0 % to −20 %

of the limit.
4.4 Overvoltage

If the system is connected to 120 % of the nominal voltage of the system for which the test

equipment is designed, neither the operator shall be harmed, nor the device be damaged.

Protective devices shall not be activated. If the device is intended to be used in IT systems, the

nominal voltage of the test equipment is the line-to-line voltage.
---------------------- Page: 12 ----------------------
IEC 61557-11:2020 © IEC 2020 – 11 –

If the test equipment is accidentally connected to 173 % of the nominal voltage in TN or TT

systems for which the test equipment is designed for the duration of 1 min, neither the operator

shall be harmed, nor the device be damaged. In this case, protective devices may be activated.

5 Marking and operating instructions
5.1 Markings

In addition to the requirements of IEC 61557-1:2019, 5.1, the following information shall be

provided on the measuring equipment.

Rated residual operating current or rated residual operating currents of the RCM for which the

test equipment has been designed for an actuating time of 10 s.

NOTE Other rated residual operating currents for a shorter duration of the actuating times can be marked in

addition.
The maximum voltage to earth and the rated measuring category shall be marked.
5.2 Operating instructions
5.2.1 General

In addition to the requirements of IEC 61557-1:2019, 5.3, the operating instructions shall

include the information and warnings set out in 5.2.2 and 5.2.3.
5.2.2 Information

a) Information about special test configurations to avoid unintended tripping of residual current

devices (RCD);
b) information to avoid unintended influences on the operation of the system;

c) information for recalibration cycles and safety tests of the test equipment after repair and

instructions for periodical tests.
5.2.3 Warnings

a) If the detecting circuit for the fault voltage has no probe and if a possible voltage between

the protective conductor and earth influences the measurements, a warning shall be

included.

b) Where the detecting circuit for the fault voltage uses the N-conductor as a probe, a warning

shall be given to test the connection between the neutral point of the distribution system

and earth before the test is started; a possible voltage between the N-conductor and earth

may influence the measurements.

c) A warning that leakage currents in the circuit following the RCM may influence

measurements and test results.

d) The earth electrode resistance of a detecting circuit for the fault voltage with a probe shall

not exceed the value stated by the manufacturer.
e) A warning that the potential fields of other earthed installation
...

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