IEC 61992-6:2006/AMD2:2020

Amendment 2 - Railway applications - Fixed installations - DC switchgear - Part 6: DC switchgear assemblies

General Information

• Status: Published
• Publication Date: 25-May-2020
• ICS: 45.060.01 - Railway rolling stock in general
• Technical Committee: TC 9 - Electrical equipment and systems for railways
• Drafting Committee: MT 61992 - TC 9/MT 61992
• Current Stage: PPUB - Publication issued
• Start Date: 26-May-2020
• Completion Date: 12-May-2020

Relations

• Amends: IEC 61992-6:2006 - Railway applications - Fixed installations - DC switchgear - Part 6: DC switchgear assemblies
• Effective Date: 05-Sep-2023

Overview

IEC 61992-6:2006/AMD2:2020 is Amendment 2 to Part 6 of IEC 61992 - the International Electrotechnical Commission standard for railway applications - fixed installations - DC switchgear assemblies. This amendment introduces a normative test method (Annex B) and additional requirements focused on internal arcing (internal arc faults) in metal‑enclosed DC switchgear used in indoor stationary railway installations. It provides guidance for assigning a rated short‑circuit current under internal arcing conditions (I_Narc) and specifies how to test assemblies to verify protection of operating staff against gas, pressure and hot products generated by internal arcs.

Key Topics and Technical Requirements

• Internal arc definition and rating: Clarifies terminology (internal arc) and allows manufacturers to assign a rated internal‑arcing short‑circuit current (I_Narc), which shall equal the rated earth‑fault current (I_Ncwe).
• Normative internal arc test (Annex B): A type test required when I_Narc is assigned. Key aspects:
  • Test duration: 150 ms
  • Test specimen: representative, metal‑enclosed, fully equipped assemblies; modular units tested as assembled in service
  • Test circuit: adjustable resistors/reactors to reproduce prospective sustained short‑circuit current; calibration per IEC 61992‑1 amendments
  • Arc initiation: ignition wire between live part and earthed part, with specified minimum wire cross‑sections depending on test current
  • Earthing: enclosure earthed to negative conductor; protections that would trip the circuit must be made ineffective during test
• Assessment criteria (Clause B.5): Five pass/fail criteria covering retained door/covers, absence of enclosure fragmentation or ejected parts (>60 g), no burn‑through holes up to 2 000 mm, non‑ignition of vertical indicators, and maintained earthing continuity.
• Test reporting: Detailed test report requirements including currents, Joule integral, oscillograms, photos and assessment against criteria.

Applications and Who Uses It

This amendment is essential for:

• Switchgear manufacturers designing and certifying DC switchgear assemblies for railway traction power
• Railway system integrators and operators validating equipment safety for indoor substations and depots
• Test laboratories and certification bodies performing internal arc type tests and producing compliance reports
• Safety and compliance engineers assessing risk, earthing arrangements and mechanical containment for switchgear installations

Adoption supports safer fixed DC installations by ensuring assemblies limit risk from internal arcing and meet traceable test evidence.

Related Standards

• IEC 61992-1 (general test methods and definitions)
• IEC 61992-7-1 (earthing considerations for DC switchgear)
• IEC 62271-200 (accessibility classes / internal arc equivalence references)

Keywords: IEC 61992-6:2006/AMD2:2020, DC switchgear assemblies, internal arc test, railway applications, fixed installations, rated short‑circuit current under internal arcing conditions.

Standards Content (Sample)

IEC 61992-6 ®
Edition 1.0 2020-05
INTERNATIONAL
STANDARD
AMENDMENT 2
Railway applications – Fixed installations – DC switchgear –
Part 6: DC switchgear assemblies

IEC 61992-6:2006-02/AMD2:2020-05(en)

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IEC 61992-6 ®
Edition 1.0 2020-05
INTERNATIONAL
STANDARD
AMENDMENT 2
Railway applications – Fixed installations – DC switchgear –

Part 6: DC switchgear assemblies

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 45.060.01 ISBN 978-2-8322-8149-9

– 2 – IEC 61992-6:2006/AMD2:2020
© IEC 2020
FOREWORD
This amendment has been prepared by IEC technical committee 9: Electrical equipment and
systems for railways.
The text of this amendment is based on the following documents:
CDV Report on voting
9/2542/CDV 9/2584A/RVC
Full information on the voting for the approval of this amendment can be found in the report
on voting indicated in the above table.
The committee has decided that the contents of this amendment and the base publication will
remain unchanged until the stability date indicated on the IEC website 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.
This amendment was elaborated to provide guidance to the requirement of 6.6.3, Internal
arcing, that gas or vapour escaping under pressure does not endanger operating staff.

_____________
3 Terms and definitions
Replace the text of Clause 3 by the following:
For the purposes of this document, the terms and definitions given in IEC 61992-1 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
3.1
internal arc
arcing within a switchgear assembly arising from a fault between active parts and/or between
active parts and other conductive parts

© IEC 2020
3.2
rated short-circuit current under internal arcing conditions
I
Narc
current, during the test duration of 150 ms, indicating the maximum allowable value of
sustained short-circuit current at the terminals of the incoming unit for which the requirements
of this test specification are fulfilled
Note 1 to entry: The value is the maximum value of the prospective sustained short-circuit current.
3.3
compartment under test
compartment of a switchgear assembly which is subject to an internal arc test
6.6.2 Internal arcing
Add the following at the end of 6.6.2:
A manufacturer may assign a rated short-circuit current under internal arcing conditions I
Narc
to the equipment. Requirements are given in Clause B.2.
8.2 List of the applicable tests
Add the following at the end of, and after, Table 2:
Internal arc test Type 8.3.9
Routine and type tests are mandatory tests if related characteristics are assigned to the
equipment.
8.3 Performance of tests
Add the following new subclause after 8.3.8:
8.3.9 Internal arc test
The internal arc test is a type test and shall be performed if a rated short-circuit current under
internal arcing conditions (I ) is assigned to the equipment. The test shall be performed
Narc
according to the procedure specified in Annex B. The criteria for successful passing are given
in Clause B.5.
Add the following new Annex B after Annex A:

– 4 – IEC 61992-6:2006/AMD2:2020
© IEC 2020
Annex B
(normative)
Method for testing under conditions of arcing due to an internal fault
B.1 Purpose of the test
Annex B applies to metal-enclosed DC switchgear assemblies - hereinafter called assemblies
- used in indoor stationary installations.
The test procedure described below is intended:
– to assess the ability of the assembly to limit the risk of personal injury,
– to verify the effectiveness of the design in protecting persons,
in case of an internal arc.
The testing conditions take into account that assemblies are installed in areas restricted to
authorized personnel.
NOTE This is equivalent to accessibility class A of IEC 62271-200:2011.
B.2 Characteristics – Rated short-circuit current under internal arcing
conditions (I )
Narc
If a rated short-circuit current under internal arcing conditions I is assigned by the
Narc
manufacturer to the equipment the value shall be equal to the rated earth fault current I .
Ncwe
The peak of the short-circuit current value is conventionally assumed to be 1,42 times the
prospective sustained short-circuit current (fault of negligible impedance).
NOTE The current level during internal arcing depends on the earthing of the switchboard frame (see
IEC 61992-7-1:2006, 6.5.7). High fault currents can be expected where the switchboard frame is:
– directly connected to the return circuit as shown in IEC 61992-7-1:2006, 6.5.7, Figure 4b, or
– connected to substation earth as shown in IEC 61992-7-1:2006, 6.5.7, Figure 4a, and a voltage limiting device
is installed between substation earth and the return circuit.
Lower fault currents can be expected where the bedding resistance of the track and the earth resistance limit the
fault current.
B.3 Test arrangements
B.3.1 Test specimen
The test shall be carried out on representative samples. In case of an assembly with a
continuous main busbar, consisting of extensible (modular) standalone units, the test
specimen shall consist of minimum two units connected together as in service.
The following points shall be observed.
– The test shall be carried out on a test specimen not previously subjected to an arcing test
or on a specimen cleaned and prepared accordingly. The specimen and the equipment in
it may be repaired or replaced before each test.
NOTE Degradation of insulation due to carbonisation or moderate erosion of metal parts is not necessarily
considered to render a unit unsuitable for a further test.
– The test specimen shall be placed in an open area and shall be fixed by its designed
means.
© IEC 2020
– Vertical indicators shall be installed all around.
– A ceiling shall be located at a distance of (200 ± 50) mm from the upper part of the test
specimen unless differently stated by the manufacturer.
If a test specimen includes a roof according to the following specification, and as shown in
Figure B.1, it shall be tested with the roof installed and an additional ceiling is not
required. The roof:
• covers the top surface completely, and
• is of a protection degree of IPX1 or higher, and
• is mounted at minimum distance dc to the top of the assembly of no more than
200 mm.
– The test specimen shall be fully equipped. Earthing and bonding shall be as for normal
service.
– Mock-ups of internal components are permitted provided that:
• they have the same volume and shape as the original items,
• similar external materials, with any metallic external material is earthed in a similar
manner to normal service.
– All doors and covers provided are closed.
– The test specimen shall be earthed at the earthing point provided.
– Secondary devices need not be installed if inside a separate compartment for control
circuits. Means for wiring from the control compartment to the compartment under test
shall be installed.
B.3.2 Test circuit
A typical diagram of the test circuit is shown
...