IEC 63522-12:2025

IEC 63522-12 ®
Edition 1.0 2025-02
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Electrical relays – Tests and measurements –
Part 12: Internal moisture
Relais électriques – Essais et mesurages –
Partie 12: Humidité interne
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IEC 63522-12 ®
Edition 1.0 2025-02
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Electrical relays – Tests and measurements –

Part 12: Internal moisture
Relais électriques – Essais et mesurages –

Partie 12: Humidité interne
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 29.120.70  ISBN 978-2-8327-0155-3

– 2 – IEC 63522-12:2025 © IEC 2025
CONTENTS
FOREWORD . 3
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 6
4 Test procedure . 6
4.1 Purpose . 6
4.2 Procedure . 6
4.2.1 General . 6
4.2.2 Method 1: External temperature impact . 6
4.2.3 Method 2: Over-energization at room temperature . 7
4.3 Conditions . 7
5 Evaluation . 7
5.1 General . 7
5.1.1 Method 1: External temperature impact . 7
5.1.2 Method 2: Over-energization at room temperature . 8
5.2 Test report . 8
Bibliography . 9

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
ELECTRICAL RELAYS – TESTS AND MEASUREMENTS –

Part 12: Internal moisture
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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preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with
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Standardization (ISO) in accordance with conditions determined by agreement between the two organizations.
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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) IEC draws attention to the possibility that the implementation of this document may involve the use of (a)
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the latest information, which may be obtained from the patent database available at https://patents.iec.ch. IEC
shall not be held responsible for identifying any or all such patent rights.
IEC 63522-12 has been prepared by subcommittee IEC technical committee 94: Electrical
relays. It is an International Standard.
The text of this International Standard is based on the following documents:
Draft Report on voting
94/1050/FDIS 94/1108/RVD
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.

– 4 – IEC 63522-12:2025 © IEC 2025
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/publications.
A list of all parts of the IEC 63522 series, published under the general title Electrical relays –
Tests and measurements, 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 webstore.iec.ch in the data related to the
specific document. At this date, the document will be
• reconfirmed,
• withdrawn, or
• revised.
ELECTRICAL RELAYS – TESTS AND MEASUREMENTS –

Part 12: Internal moisture
1 Scope
This document is used for testing electromechanical elementary relays (electromechanical
relays, reed relays, reed contacts, reed switches and technology combinations of these) and
evaluates their ability to perform under expected conditions of transportation, storage, and all
aspects of operational use.
This document defines a standard test method to provoke internal moisture inside relays by
different methods. The device under test (DUT) is tested at its specified energization values
throughout the defined temperature range.
The test methods in this document are applicable to RT III, RT IV and RT V products only, i.e.,
wash-tight, sealed, and hermetically sealed DUTs.
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 63522-0:— , Electrical relays – Tests and measurements – Part 0: Testing – General and
guidance
IEC 63522-1, Electrical relays – Tests and measurements – Part 1: Visual inspection and check
of dimensions
IEC 63522-5, Electrical relays – Tests and measurements – Part 5: Insulation resistance
IEC 63522-6, Electrical relays – Tests and measurements – Part 6: Contact-circuit resistance
(or voltage drop)
IEC 63522-7, Electrical relays – Tests and measurements – Part 7: Functional tests
___________
First edition under preparation. Stage at the time of publication: IEC CDV 63522-0:2024.
First edition under preparation. Stage at the time of publication: IEC FDIS 63522-1:2024.
First edition under preparation. Stage at the time of publication: IEC FDIS 63522-5:2024.

– 6 – IEC 63522-12:2025 © IEC 2025
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 63522-0 apply.
ISO and IEC maintain terminology databases for use in standardization at the following
addresses:
• IEC Electropedia: available at https://www.electropedia.org/
• ISO Online browsing platform: available at https://www.iso.org/obp
4 Test procedure
4.1 Purpose
The purpose of this test procedure is to determine whether internal moisture has an adverse
effect on certain properties of the DUT, and that it can perform as required at its specified
energization values throughout the defined temperature range.
NOTE The test methods defined in this document will not yield comparable results due to the different sources of
heat.
4.2 Procedure
4.2.1 General
The tests stated in this document shall be carried out with appropriate test conditions and
severities, as well as suitable measurement conditions.
The DUT shall be in a new and clean condition, mounted as in service or mounted as specified
by the manufacturer. Unless otherwise stated in this document, the test shall be performed
under applicable reference conditions given in IEC 63522-0:— , 4.4.
A minimum of five DUTs shall be tested, the preferred number of DUTs being 10.
Internal moisture can create statistical effects due to the variety of possible moisture distribution
patterns. Therefore, a number of DUTs greater than 5 is recommended.
4.2.2 Method 1: External temperature impact
The DUT coil shall be energized as specified in 4.3 c) while the DUT is under its maximum rated
operating temperature for 1 h, and then under the minimum rated operating temperature for an
additional 1 h. Unless otherwise specified, the temperature change shall occur at a rate of
(5 ± 1) K/min.
During the test procedure, measure and monitor the insulation resistance between all contacts
and the DUT enclosure at 20 min intervals in accordance with IEC 63522-5.
At the end of the low temperature exposure, the coil shall be de-energized, or, for bistable
DUTs, the rated reset voltage shall be momentarily applied. The corresponding function of the
DUT shall be monitored and a final insulation resistance measurement between all contacts
and the DUT enclosure shall be carried out in accordance with IEC 63522-5.
___________
First edition under preparation. Stage at the time of publication: IEC CDV 63522-0:2024.

The function may be monitored via the contact state according to IEC 63522-0 or other suitable
measurements on the terminals or coils.
NOTE Other preferred values for temperature change rates are given in IEC 60068-2-14.
4.2.3 Method 2: Over-energization at room temperature
The DUT coil shall be energized at room temperature at 140 % of its rated energization value
for 2,5 min. Measure and monitor the insulation resistance between all contacts and the DUT
enclosure at 30 s intervals in accordance with IEC 63522-5. The maximum coil heating due to
the allowed duty cycle shall be considered.
4.3 Conditions
The conditions to be specified are the following:
a) method 1 or 2, or both, in accordance with 4.2.2 or 4.2.3, respectively. If both methods are
specified to be carried out, the methods shall not be carried out on the same DUT. Each
method shall be considered as an independent test on a new set of DUTs in accordance
with 4.2.1;
b) number of DUTs used for the test (new DUTs to be used for method 1 and method 2);
c) rated energization quantity (if not specified differently);
d) for method 1 only: maximum and minimum rated operating temperature, temperature change
rate, monitoring procedure, functional testing parameters as specified in IEC 63522-7;
e) for methods 1 and 2: test conditions, measurement setup, measurement time and limit value
of insulation resistance, as required by IEC 63522-5. Unless otherwise specified,
recommended values are:
• measurement time: 60 s for method 1 and 5 s for method 2;
• insulation resistance: ≥ 1 MΩ for basic insulation, ≥ 2 MΩ for reinforced insulation.
5 Evaluation
5.1 General
5.1.1 Method 1: External temperature impact
After the test, the DUTs shall be in good condition, and it shall be verified that the contact(s)
has (have) changed their state. Neither any of the insulation resistance readings during the
20 min intervals, nor the final insulation resistance reading shall be lower than the value as
specified in 4.3 e). All those insulation resistance data shall be measured in accordance with
IEC 63522-5.
The following tests shall be carried out at room temperature within 30 min after the test
procedure:
a) visual inspection as specified in IEC 63522-1. The DUTs shall not show any signs of damage
or corrosion. Dimensional checks are not required.
b) functional test as specified in IEC 63522-7. The DUTs shall respond to each functional test
step with its intended contact state for each defined voltage step.
c) insulation resistance measurement between all contacts and the DUT s
...