IEC 61000-4-25:2001

IEC 61000-4-25 ®
Edition 1.2 2019-12
CONSOLIDATED VERSION
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Electromagnetic compatibility (EMC) –
Part 4-25: Testing and measurement techniques – HEMP immunity test methods
for equipment and systems
Compatibilité électromagnétique (CEM) –
Partie 4-25: Techniques d’essai et de mesure – Méthodes d’essai d’immunité à
l’IEMN-HA des appareils et des systèmes

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IEC 61000-4-25 ®
Edition 1.2 2019-12
CONSOLIDATED VERSION
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Electromagnetic compatibility (EMC) –

Part 4-25: Testing and measurement techniques – HEMP immunity test methods

for equipment and systems
Compatibilité électromagnétique (CEM) –

Partie 4-25: Techniques d’essai et de mesure – Méthodes d’essai d’immunité à

l’IEMN-HA des appareils et des systèmes

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 33.100.99 ISBN 978-2-8322-7734-8

IEC 61000-4-25 ®
Edition 1.2 2019-12
CONSOLIDATED VERSION
REDLINE VERSION
VERSION REDLINE
colour
inside
Electromagnetic compatibility (EMC) –
Part 4-25: Testing and measurement techniques – HEMP immunity test methods
for equipment and systems
Compatibilité électromagnétique (CEM) –
Partie 4-25: Techniques d’essai et de mesure – Méthodes d’essai d’immunité à
l’IEMN-HA des appareils et des systèmes

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CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
2 Normative references . 7
3 Definitions . 8
4 General . 12
5 Immunity tests and immunity test levels . 12
5.1 Introduction . 12
5.2 Immunity tests . 12
5.3 Immunity test levels . 12
5.4 Radiated disturbance tests . 12
5.4.1 Radiated immunity test levels . 12
5.4.2 Radiated immunity test specifications . 13
5.4.3 Small radiated test facilities . 14
5.4.4 Large HEMP simulators . 14
5.4.5 Frequency domain spectrum requirements . 16
5.5 Conducted disturbance tests . 16
5.5.1 Conducted immunity test levels . 16
5.5.2 Conducted immunity test specifications . 20
6 Test equipment . 21
6.1 Radiated field tests. 21
6.1.1 Radiated field generator . 21
6.1.2 Instrumentation. 21
6.2 Conducted disturbance tests . 22
6.2.1 Test generator . 22
6.2.2 Instrumentation. 23
7 Test set-up . 24
7.1 Radiated disturbance test . 24
7.2 Conducted disturbance test . 24
8 Test procedure . 25
8.1 Climatic conditions . 25
8.2 Immunity test level and test exposures . 25
8.3 Radiated disturbance test procedure . 26
8.3.1 Test parameter measurements . 26
8.3.2 Radiated test procedure . 26
8.4 Conducted disturbance immunity test procedure. 28
8.5 Test execution . 28
8.5.1 Execution of the radiated immunity test . 28
8.5.2 Execution of the conducted immunity test . 29
9 Test results and test reports . 29
Annex A (informative) Rationale for the immunity test levels . 30
Annex B (informative) Conducted immunity tests for antennas . 38
Annex C (informative) Conducted disturbance immunity tests . 40
Annex D (normative informative) Damped oscillatory wave test . 44

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Figure 1 – Frequency domain spectral magnitude between 100 kHz and 300 MHz. . 14
Figure C.1 – Block diagram for EC10 and EC11 immunity tests . 41
Figure C.2 – Example of a simplified circuit diagram of a fast transient/burst generator . 41
Figure C.3 – Waveshape of an EC10 pulse into a 50 Ω load . 42
Figure C.4 – Example of an EC11 generator (see clause C.1 for details) . 42
Figure C.5 – Waveshape of an EC11 pulse into a 50 Ω load . 43
Figure C.6 – Simplified block diagram for LC immunity test levels . 43
Figure C.7 – Waveshape of the LC slow pulse . 43

Table 1 – Radiated immunity test levels defined in the present standard . 13
Table 2 – Early time conducted immunity test levels . 18
Table 3 – Intermediate time HEMP conducted immunity test levels . 19
Table 4 – Conducted environment immunity test levels for late-time HEMP . 20
Table 5 – Late time HEMP conducted environment effects tests for low-voltage a.c.
power ports . 20
Table 6 – Conducted HEMP immunity test specifications . 21
Table A.1 – Radiated immunity test levels . 31
Table A.2 – Conducted common-mode early time HEMP environments . 32
Table A.3 – Early time HEMP conducted environments on LV circuits (low-voltage
circuits up to 1 000 V) . 33
Table A.4 – Conducted environments for early time HEMP . 34
Table A.5 – Early time HEMP conducted environments immunity test levels for LV
circuits (low-voltage circuits up to 1000 V) . 35
Table A.6 – Example early time HEMP immunity test levels for various applications. . 36
Table D.1 – ISO 7137 test procedure reference number 3.8 . 44
Table D.2 – VG current injection test . 45
Table D3 – MIL-STD-461-E . 45

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INTERNATIONAL ELECTROTECHNICAL COMMISSION
___________
ELECTROMAGNETIC COMPATIBILITY (EMC) –
Part 4-25: Testing and measurement techniques –
HEMP immunity test methods for equipment and 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 addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
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4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
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other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
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.
This consolidated version of the official IEC Standard and its amendments has been
prepared for user convenience.
IEC 61000-4-25 edition 1.2 contains the first edition (2001-11) [documents 77C/113/FDIS
and 77C/117/RVD], its amendment 1 (2012-03) [documents 77C/216/FDIS and 77C/218/
RVD] and its amendment 2 (2019-12) [documents 77C/285/CDV and 77C/290/RVC].
In this Redline version, a vertical line in the margin shows where the technical content
is modified by amendments 1 and 2. Additions are in green text, deletions are in
strikethrough red text. A separate Final version with all changes accepted is available
in this publication.
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International Standard IEC 61000-4-25 has been prepared by subcommittee 77C: High power
transient phenomena, of IEC technical committee 77: Electromagnetic compatibility.
It forms part 4-25 of IEC 61000. It has the status of a basic EMC publication in accordance
with IEC Guide 107.
Annex D forms an integral part of this standard.
Annexes A, B C and D are for information only.
The committee has decided that the contents of the base publication and its amendments will
remain unchanged until the stability 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.
IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct
understanding of its contents. Users should therefore print this document using a
colour printer.
– 6 – IEC 61000-4-25:2001+AMD1:2012
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INTRODUCTION
This standard is part of the IEC 61000 series, according to the following structure:
Part 1: General
General considerations (introduction, fundamental principles)
Definitions, terminology
Part 2: Environment
Description of the environment
Classification of the environment
Compatibility levels
Part 3: Limits
Emission limits
Immunity limits (in so far as they do not fall under the responsibility of product
committees)
Part 4: Testing and measurement techniques
Measurement techniques
Testing techniques
Part 5: Installation and mitigation guidelines
Installation guidelines
Mitigation methods and devices
Part 6: Generic standards
Part 9: Miscellaneous
Each part is further subdivided into several parts, published either as International Standards
or as technical specifications or technical reports, some of which have already been published
as sections. Others will be published with the part number followed by a dash and completed
by a second number identifying the subdivision (example: 61000-6-1).

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ELECTROMAGNETIC COMPATIBILITY (EMC) –

Part 4-25: Testing and measurement techniques –
HEMP immunity test methods for equipment and systems

1 Scope
This part of IEC 61000 describes the immunity test levels and related test methods for
electrical and electronic equipment and systems exposed to high-altitude electromagnetic
pulse (HEMP) environments. It defines ranges of immunity test levels and establishes test
procedures. Specifications for test equipment and instrumentation test set-up, test
procedures, pass/fail criteria, and test documentation requirements are also defined by this
standard. These tests are intended to demonstrate the immunity of electrical and electronic
equipment when subjected to HEMP radiated and conducted electromagnetic disturbances.
For radiated disturbance immunity tests, specifications are defined in this standard both for
small test facilities and large HEMP simulators.
This part of IEC 61000 defines specifications for laboratory immunity tests. On-site tests
performed on equipment in the final installation to verify immunity are also specified. These
verification tests use the same specifications as laboratory tests, except for the climatic
environmental specifications.
The objective of this part of IEC 61000 is to establish a common and reproducible basis for
evaluating the performance of electrical and electronic equipment, when subjected to HEMP
radiated environments and the associated conducted transients on power, antenna, and
input/output (I/O) signal and control lines.
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 60050(161), International Electrotechnical Vocabulary – Chapter 161: Electromagnetic
compatibility
IEC 60038, IEC standard voltages
IEC 60068-1:1988, Environmental testing – Part 1: General and guidance
IEC 61000-2-5, Electromagnetic compatibility (EMC) – Part 2: Environment – Section 5:
Classification of electromagnetic environments. Basic EMC publication
IEC 61000-2-9, Electromagnetic compatibility (EMC) – Part 2: Environment – Section 9:
Description of HEMP environment – Radiated disturbance. Basic EMC publication
IEC 61000-2-10:1998, Electromagnetic compatibility (EMC) – Part 2-10: Environment –
Description of HEMP environment – Conducted disturbance
IEC 61000-2-11, Electromagnetic compatibility (EMC) – Part 2: Environment – Section 11:
Classification of HEMP environments. Basic EMC publication

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IEC 61000-4-4, Electromagnetic compatibility (EMC) – Part 4: Testing and measurement
techniques – Section 4: Electrical fast transient/burst immunity test. Basic EMC Publication
IEC 61000-4-5, Electromagnetic compatibility (EMC) – Part 4: Testing and measurement
techniques – Section 5: Surge immunity test
IEC 61000-4-11, Electromagnetic compatibility (EMC) – Part 4: Testing and measurement
techniques – Section 11: Voltage dips, short interruptions and voltage variations immunity
tests
IEC 61000-4-12, Electromagnetic compatibility (EMC) – Part 4: Testing and measurement
techniques – Section 12: Oscillatory waves immunity test
IEC 61000-4-13, Electromagnetic compatibility (EMC) – Part 4-13: Testing and measurement
techniques – Harmonics and interharmonics including mains signalling at a.c. power port, low
frequency immunity tests – Basic EMC Publication
IEC 61000-4-18, Electromagnetic compatibility (EMC) – Part 4-18: Testing and measurement
techniques – Damped oscillatory wave immunity test
IEC 61000-4-20, Electromagnetic compatibility (EMC) – Part 4-20: Testing and measurement
techniques – Emission and immunity testing in transverse electromagnetic (TEM)
waveguides
IEC 61000-4-33, Electromagnetic compatibility (EMC) – Part 4-33: Testing and measurement
techniques – Measurement methods for high-power transient parameters
IEC 61000-5-3, Electromagnetic compatibility (EMC) – Part 5-3: Installation and mitigation
guidelines – HEMP protection concepts
IEC 61000-5-4/TR, Electromagnetic compatibility (EMC) – Part 5: Installation and mitigation
guidelines – Section 4: Immunity to HEMP – Specifications for protective devices against
HEMP radiated disturbance. Basic EMC Publication
IEC 61024-1, Protection of structures against lightning – Part 1: General principles
ISO 7137, Aircraft – Environmental conditions and test procedures for airborne equipment
3 Definitions
For the purpose of this part of IEC 61000, the following definitions apply.
3.1
compatibility level
specified electromagnetic disturbance level used as a reference level for co-ordination in the
setting of emission and immunity limits
[IEV 161-03-10]
3.2
coupling (HEMP)
interaction of electromagnetic fields with a system to produce currents and voltages on
system surfaces and cables
___________
To be published
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3.3
coupling clamp
device of defined dimensions and characteristics for common mode coupling of the
disturbance signal to the circuit under test without any galvanic connection to it
3.4
coupling network
electrical circuit for the purpose of transferring energy from one circuit to another
3.5
decoupling network
electrical circuit for the purpose of preventing over-voltages applied to the EUT from affecting
other devices, equipment or systems, which are not under test
3.6
degradation (of performance)
undesired departure in the operational performance of any device, equipment or system from
its intended performance
NOTE The term “degradation” can apply to a temporary or permanent failure.
[IEV 161-01-19]
3.7
electromagnetic disturbance
any electromagnetic phenomenon which may degrade the performance of a device,
equipment or system
[IEV 161-01-05, modified]
3.8
electromagnetic interference
degradation of the performance of a device, transmission channel or system caused by an
electromagnetic disturbance
[IEV 161-01-06]
3.9
electromagnetic susceptibility
inability of a device, equipment or system to perform without degradation in the presence of
an electromagnetic disturbance
NOTE Susceptibility is a lack of immunity.
[IEV 161-01-21]
3.10
EUT (equipment under test)
the equipment under test can be a single unit or multiple units interconnected by cables, data
links, etc.
NOTE Multiple units interconnected by cables, etc. are also called a system [see 3.27 below].
3.11
fast Fourier transform
FFT
mathematical procedure for rapidly computing the direct or inverse Fourier transform of a time
m
domain signal or of a frequency domain spectrum, respectively. It requires 2 (m = integer)
data points that are equally spaced in time or frequency, and involves much less computation
time than a standard discrete Fourier transform (DFT)

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3.12
ground reference plane
flat conductive surface, whose potential is used as a common reference
[IEV 161-04-36]
3.13
HV transmission line
power line with a nominal a.c. system voltage equal to or greater than 100 kV
3.14
short circuit current
I
sc
current resulting from an abnormal connection of relatively low resistance between two points
of different potentials in a circuit
3.15
immunity (to a disturbance)
ability of a device, equipment or system to perform without degradation in the presence of an
electromagnetic disturbance
[IEV 161-01-20]
3.16
immunity level
maximum level of a given electromagnetic disturbance incident on a particular device,
equipment or system for which it remains capable of operating at a required degree of
performance
[IEV 161-03-14]
3.17
immunity test level
value of an influencing electromagnetic quantity specified for an immunity test
NOTE It is to be noted that the text of this definition is the same as for severity level. A test standard can specify
several severity levels according to different immunity levels.
3.18
large HEMP simulator
transient electromagnetic pulse test facility with a test volume sufficiently large to test objects
with cubical dimensions equal to or greater than 1 m × 1 m × 1 m
3.19
LV (low-voltage) power circuit
power circuit with a nominal a.c. voltage between 120 V and 1 000 V
NOTE The standard voltages in this voltage range are presented in IEC 60038.
3.20
MV (medium voltage) distribution power line
power line with a nominal a.c. voltage above 1 kV and not exceeding 35 kV used to distribute
power within a local area
NOTE The standard voltages in this voltage range are presented in IEC 60038.
3.21
point-of-entry
port-of-entry
PoE
the physical location (point/port) on the electromagnetic barrier, where EM energy may enter
or exit a topological volume, unless an adequate PoE protective device is provided. A PoE is

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not limited to a geometrical point. PoEs are classified as aperture PoEs or conductor PoEs,
according to the type of penetration. They are also classified as architectural, mechanical,
structural or electrical PoEs, according to the architectural engineering discipline in which
they are usually encountered
3.22
pulse width
time interval between the points on the leading and trailing edges of a pulse at which the
instantaneous value is 50 % of the peak pulse amplitude
3.23
rise time (of a pulse)
interval of time between the instants at which the instantaneous value of a pulse first reaches
a specified lower value and then a specified upper value
[IEV 161-02-05]
NOTE In this standard, the lower value is ten (10) percent of the peak, and the upper value is ninety (90) percent
of the peak value
3.24
severity level
value of an influencing electromagnetic quantity specified for an immunity test
NOTE It is to be noted that the text of this definition is the same as for immunity test level. A test standard can
specify several severity levels according to different immunity levels.
3.25
small radiated test facility
laboratory transient electromagnetic pulse test facility such as a TEM cell with a test volume
sufficiently large to test objects with cubical dimensions less than 1 × 1 × 1 meter
3.26
surge protection device (SPD)
device to suppress line conducted overvoltages and currents
NOTE Examples are surge suppressors defined in IEC 61024-1.
3.27
system
multiple equipment or electrical units connected by cables, data links, etc.
3.28
test volume
volume in which the incident electromagnetic fields meet, or exceed, the required strength
and field uniformity requirements.
3.29
transient
phenomenon which varies between two consecutive steady states during a time interval short
compared with the time-scale of interest
[IEV 161-02-01]
3.30
open circuit voltage
V
oc
voltage between points in a circuit where one of the points was created by opening or
breaking the circuit
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4 General
The nuclear high-altitude electromagnetic pulse test consists of two major parts: radiated
immunity testing and conducted immunity testing. The radiated immunity test is performed for
the purpose of demonstrating that the equipment under test has the ability to continue
functioning when exposed to radiated HEMP fields. Similarly, the conducted immunity test is
performed for the purpose of demonstrating that the equipment under test will not be
adversely affected by exposure to conducted HEMP transients. These transients are current
and voltage pulses on conductors (wires, cables) that are connected to the equipment. In
general, conducted HEMP transients induced in power and telecom lines are often the most
severe threats to equipment. The immunity tests described in this standard involve hazardous
voltages. High-voltage precautions will be necessary to protect the health and safety of test
personnel.
5 Immunity tests and immunity test levels
5.1 Introduction
This standard has been developed to specify the HEMP immunity test for electrical or
electronic equipment and systems. The intent is to allow manufacturers to qualify equipment
early in the design cycle, and to use many of the same IEC laboratory immunity tests that are
already prescribed for other EMC purposes.
5.2 Immunity tests
HEMP immunity tests consist of two major types: radiated immunity tests and conducted
immunity tests. For the purpose of this standard, the term "electronic equipment" denotes an
apparatus that performs a specific function. This could be a small computer or a telephone.
Some equipment (for example, a computer connected to additional peripherals such as
control boards to monitor processes in a factory) may be considered as part of a larger
system. Often, electronic equipment are relatively small – on the order of 1 m x 1 m x 1 m or
smaller. It is expected that most of the tests on such small equipment will be performed in
laboratories using current injection simulators and TEM cells.
For HEMP (and EMC) tests, size can be an important factor, since very large systems may be
difficult to test, especially by radiated fields. In general, radiated field tests on systems and
large equipment with dimensions greater than 1 m on a side will require a large HEMP
simulator. One aspect of HEMP testing that is different from other kinds of EMC testing is that
there are several large (∼10 m high) early-time (t < 1 µs) HEMP simulators throughout the
world. It is possible to expose some systems and large equipment to the early-time HEMP
threat by reproducing the pulsed electric and magnetic fields. These simulators are also
useful in verifying that equipment designed and tested for HEMP survival at the equipment
level, will work properly when integrated into a complete system.
5.3 Immunity test levels
This standard defines electromagnetic disturbances that represent those which could result at
the equipment ports due to a high-altitude nuclear event. These electromagnetic disturbances
will be the result of the radiated and conducted HEMP environments, as modified by any
protection elements. These electromagnetic disturbances are described in IEC 61000-2-9,
IEC 61000-2-10 and IEC 61000-2-11. The rationale for the immunity test levels and threat
reductions due to protection elements and probable flashovers are described in annex A.
5.4 Radiated disturbance tests
5.4.1 Radiated immunity test levels
The radiated immunity test levels described below involve only the early time radiated fields.
Testing for the intermediate-time and late-time HEMP fields are not required. Information

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regarding the selection of the immunity test levels is given in annex A. The peak values of the
early-time electric field, E , for selected immunity test levels are listed in table 1.
peak
Table 1 – Radiated immunity test levels defined in the present standard
b
Immunity test level Test required for equipment and E-field peak value
a
systems with the following protection
E (kV/m)
peak
R1 Concept 4 0,5
R2 Intermediate value 1
R3 Intermediate value 2
R4 Concepts 2A, 2B, 3 5
R5 Intermediate value 10
R6 Intermediate value 20
R7 Concepts 1A, 1B 50
RX Special applications X
a
The protection concepts are described in IEC 61000-5-3
b
According to IEC 61000-2-11, table 2

5.4.2 Radiated immunity test specifications
In the absence of an object in the simulator, the electric field in the test volume is a wave
comparable to a quasi-plane wave, with a double exponential pulse time history described by
a 2,5/25 ns wave, i.e. a unipolar wave with a 10 %-90 % rise time of 2,5 ns and a pulse width
equal to 25 ns. This waveform is given by the equation below.
−βt −αt
E(t) = E × k × (e − e )     V/m (1)
peak
where
8 -1 7 -1
α = 6,0 × 10 s , β = 4,0 × 10 s , and
k = 1,3.
E is the peak value of the electric field in volts per meter.
peak
NOTE E is the immunity test level selected from table 1.
peak
t is the time in seconds.
The frequency-domain spectral magnitude for equation (1) is given by
E × k ×(α − β )
peak
E( f ) =  (V/m/Hz) (2)
[((2 πf )² + α²) ((2 πf )² + β ²)]
where
f is the frequency in hertz.
For the waveform parameters given above, the frequency-domain spectral magnitude of
equation (2) is shown in figure 1.

– 14 – IEC 61000-4-25:2001+AMD1:2012
+AMD2:2019 CSV  IEC 2019
1E–7
1E–8
1E–9
1E–10
0,1 1 10 100
Frequency  MHz
IEC  2168/01
Figure 1 – Frequency domain spectral magnitude between 100 kHz and 300 MHz.
5.4.3 Small radiated test facilities
Small test facilities can more easily meet the desired field specifications with smaller
tolerances in parameter variations than the large HEMP simulators. These small facilities will
be used primarily to test relatively small equipment. Tolerances for the early-time HEMP pulse
waveform over the entire parallelepiped test volume of the small test facility shall be as
follows.
– The ratio of the peak electric field to the peak magnetic field shall be equal to 377 Ω ±
50 Ω with a tolerance of ±75 Ω.
– The rise time between 10 % and 90 % of the peak value shall be within the range of 2,0 ns
and 2,5 ns with a tolerance of ±0,5 ns.
– The electric field shall be continuously increasing during the 10 % and 90 % rise time.
– The pulse width (the time duration between points on the leading and trailing edges of the
pulse at 50 % of E ) shall be within the range of 25 ns and 30 ns 23 ns with a tolerance
peak
of ±5 ns.
– The magnitude of any pre-pulse on the electric field shall be equal to or less than 7 % of
the magnitude of the peak field.
– Electric field reflections from the terminator of the simulator shall be less than 10 %.
– Fluctuations in the smoothed frequency spectrum of the electric field at the centre of the
test volume (see 5.4.5) shall not be larger than ±3 dB compared to the theoretical
spectrum given by equation (2) in the bandwidth between 100 kHz and 300 MHz.
– At the time of the peak value of the simulated fields, other non-principal electromagnetic
components shall be smaller than 10 % of the peak value of the simulated field.
– The peak electric field shall be uniform in the test volume to within the following criteria:
the peak electric field within the test volume shall be within the range of E and
peak
E + 6 dB.
peak
– To evaluate the field tolerances, electric and magnetic field measurements at the centre
and the eight corners of the test volume shall be performed in the absence of the EUT.
5.4.4 Large HEMP simulators
Large HEMP simulators can be used to test large equipment and complete systems. Due to
the variety of such simulators, there are wide ranges of rise times, pulse widths and
amplitudes of the fields produced by these devices. Consequently, large HEMP simulators are

E (f)/E
 
peak
(1/Hz)
+AMD2:2019 CSV  IEC 2019
divided into two types, based on their radiated field behaviour: types I and II. Generally, type I
simulators provide a shorter rise time and pulse width than do the type II simulators. A pre-
test analysis is required for tests with type II simulators, since these test facilities do not meet
the radiated immunity specifications given in 5.4.2.
The response of an electrical component within a system due to HEMP depends not only on
the pulse shape (or frequency domain spectrum), but also on the coupling and penetration
mechanism that the HEMP signals use in propagating from the external portions of the system
to the component. In some classes of systems (i.e., small systems with no long conducting
appendages, like a mobile telephone), the HEMP coupling will be dominated by aperture
penetrations – an inherently high frequency mechanism. Consequently, the type I simulators
having a larger high frequency spectral content would be desirable for testing. However, in
other types of systems containing longer external conductors (a HF radio, for example), the
dominant HEMP response will result from the field coupling to the antenna. Thus, the type II
simulators with a slower rise and longer pulse width would likely be adequate for testing these
particular systems.
The fact that different systems can react to different components of the incident HEMP
environment illustrates the point that a pre-test analysis program is necessary for type II
simulators. The pre-test analysis shall be performed to determine exactly how the type II
simulated fields will couple to the system, and to assess the adequacy of the type II
simulators for performing the immunity test. The adequacy of the test shall be demonstrated
by comparing the interaction and coupling results of the simulated fields with those of the
theoretical pulse described in 5.4.2.
5.4.4.1 Large HEMP simulators − type I
For testing in the type I simulators, the peak electric field, (E ) shall be chosen from
peak
Table 1 corresponding to the immunity test level selected for the test. Tolerances for the
early-time HEMP pulse over the entire parallelepiped test volume of the simulator shall be as
follows.
– The ratio of the peak electric field to the peak magnetic field shall be equal to 377 Ω ±
50 Ω with a tolerance of ±75 Ω.
– The rise time between 10 % and 90 % of the peak value shall be 2,5 ns with a tolerance
of ±0,5 ns.
– The electric field shall be continuously increasing during the 10 % and 90 % rise time.
– The pulse width (the time duration between points on the leading and trailing edges of the
pulse at 50 % of E ) shall be within the range of 25 ns and 75 ns 23 ns with a tolerance
peak
of -5 ns /+50 ns.
– The magnitude of any pre-pulse on the electric field shall be equal to or less than 7 % of
the magnitude of the peak field.
– Electric field reflections from the terminator of the simulator shall be less than 10 %.
– Fluctuations in the smoothed frequency spectrum of the electric field at the centre of the
test volume (see 5.4.5) shall not be larger than ±10 dB compared to the theoretical
spectrum given by equation (2) in the bandwidth between 1 MHz and 200 MHz.
– The peak electric field shall be uniform in the test volume to within the following criteria:
the peak electric field within the test volume shall b
...

IEC 61000-4-25 ®
Edition 1.1 2012-05
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Electromagnetic compatibility (EMC)
Part 4-25: Testing and measurement techniques – HEMP immunity test methods
for equipment and systems
Compatibilité électromagnétique (CEM)
Partie 4-25: Techniques d’essai et de mesure – Méthodes d’essai d’immunité à
l’IEMN-HA des appareils et des systèmes

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IEC 61000-4-25 ®
Edition 1.1 2012-05
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Electromagnetic compatibility (EMC)

Part 4-25: Testing and measurement techniques – HEMP immunity test methods

for equipment and systems
Compatibilité électromagnétique (CEM)

Partie 4-25: Techniques d’essai et de mesure – Méthodes d’essai d’immunité à

l’IEMN-HA des appareils et des systèmes

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX CN
ICS 33.100.99 ISBN 978-2-88912-055-0

– 2 – 61000-4-25  IEC:2001+A1:2012
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
2 Normative references. 7
3 Definitions . 8
4 General . 11
5 Immunity tests and immunity test levels . 12
5.1 Introduction . 12
5.2 Immunity tests . 12
5.3 Immunity test levels . 12
5.4 Radiated disturbance tests . 12
5.4.1 Radiated immunity test levels . 12
5.4.2 Radiated immunity test specifications . 13
5.4.3 Small radiated test facilities . 14
5.4.4 Large HEMP simulators . 14
5.4.5 Frequency domain spectrum requirements . 16
5.5 Conducted disturbance tests . 16
5.5.1 Conducted immunity test levels . 16
5.5.2 Conducted immunity test specifications . 19
6 Test equipment . 20
6.1 Radiated field tests . 20
6.1.1 Radiated field generator . 20
6.1.2 Instrumentation . 20
6.2 Conducted disturbance tests . 21
6.2.1 Test generator . 21
6.2.2 Instrumentation . 23
7 Test set-up . 23
7.1 Radiated disturbance test . 23
7.2 Conducted disturbance test . 23
8 Test procedure . 24
8.1 Climatic conditions. 24
8.2 Immunity test level and test exposures . 25
8.3 Radiated disturbance test procedure . 25
8.3.1 Test parameter measurements . 25
8.3.2 Radiated test procedure . 25
8.4 Conducted disturbance immunity test procedure . 27
8.5 Test execution . 27
8.5.1 Execution of the radiated immunity test . 27
8.5.2 Execution of the conducted immunity test . 28
9 Test results and test reports . 28

61000-4-25  IEC:2001+A1:2012 – 3 –
Annex A (informative) Rationale for the immunity test levels . 29
Annex B (informative) Conducted immunity tests for antennas . 38
Annex C (informative) Conducted disturbance immunity tests . 40
Annex D (normative informative) Damped oscillatory wave test . 44

Figure 1 – Frequency domain spectral magnitude between 100 kHz and 300 MHz. 14
Figure C.1 – Block diagram for EC10 and EC11 immunity tests . 41
Figure C.2 – Example of a simplified circuit diagram of a fast transient/burst generator . 41
Figure C.3 – Waveshape of an EC10 pulse into a 50 Ω load . 42
Figure C.4 – Example of an EC11 generator (see clause C.1 for details) . 42
Figure C.5 – Waveshape of an EC11 pulse into a 50 Ω load . 43
Figure C.6 – Simplified block diagram for LC immunity test levels . 43
Figure C.7 – Waveshape of the LC slow pulse . 43

Table 1 – Radiated immunity test levels defined in the present standard . 13
Table 2 – Early time conducted immunity test levels . 17
Table 3 – Intermediate time HEMP conducted immunity test levels . 18
Table 4 – Conducted environment immunity test levels for late-time HEMP . 19
Table 5 – Late time HEMP conducted environment effects tests for low-voltage a.c.
power ports . 19
Table 6 – Conducted HEMP immunity test specifications . 20
Table A.1 – Radiated immunity test levels . 30
Table A.2 – Conducted common-mode early time HEMP environments . 31
Table A.3 – Early time HEMP conducted environments on LV circuits
(low-voltage circuits up to 1 000 V) . 32
Table A.4 – Conducted environments for early time HEMP . 33
Table A.5 – Early time HEMP conducted environments immunity test levels for LV
circuits (low-voltage circuits up to 1000 V) . 34
Table A.6 – Example early time HEMP immunity test levels for various applications. . 35
Table D.1 – ISO 7137 test procedure reference number 3.8 . 44
Table D.2 – VG current injection test . 45
Table D3 – MIL-STD-461-E . 45

– 4 – 61000-4-25  IEC:2001+A1:2012
INTERNATIONAL ELECTROTECHNICAL COMMISSION
___________
ELECTROMAGNETIC COMPATIBILITY (EMC) –

Part 4-25: Testing and measurement techniques –
HEMP immunity test methods for equipment and systems

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
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2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
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3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
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patent rights. IEC shall not be held responsible for identifying any or all such patent rights.

This consolidated version of IEC 61000-4-25 consists of the first edition (2001)
[documents 77C/113/FDIS and 77C/117/RVD] and its amendment 1 (2012) [documents
77C/216/FDIS and 77C/218/RVD]. It bears the edition number 1.1.
The technical content is therefore identical to the base edition and its amendment and
has been prepared for user convenience. A vertical line in the margin shows where the
base publication has been modified by amendment 1. Additions and deletions are
displayed in red, with deletions being struck through.

61000-4-25  IEC:2001+A1:2012 – 5 –
International Standard IEC 61000-4-25 has been prepared by subcommittee 77C: High power
transient phenomena, of IEC technical committee 77: Electromagnetic compatibility.
It forms part 4-25 of IEC 61000. It has the status of a basic EMC publication in accordance with
IEC Guide 107.
Annex D forms an integral part of this standard.
Annexes A, B C and D are for information only.
The committee has decided that the contents of the base publication and its amendments will
remain unchanged until the stability 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.
IMPORTANT – The “colour inside” logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct understanding
of its contents. Users should therefore print this publication using a colour printer.

– 6 – 61000-4-25  IEC:2001+A1:2012
INTRODUCTION
This standard is part of the IEC 61000 series, according to the following structure:
Part 1: General
General considerations (introduction, fundamental principles)
Definitions, terminology
Part 2: Environment
Description of the environment
Classification of the environment
Compatibility levels
Part 3: Limits
Emission limits
Immunity limits (in so far as they do not fall under the responsibility of product committees)
Part 4: Testing and measurement techniques
Measurement techniques
Testing techniques
Part 5: Installation and mitigation guidelines
Installation guidelines
Mitigation methods and devices
Part 6: Generic standards
Part 9: Miscellaneous
Each part is further subdivided into several parts, published either as International Standards
or as technical specifications or technical reports, some of which have already been published
as sections. Others will be published with the part number followed by a dash and completed
by a second number identifying the subdivision (example: 61000-6-1).

61000-4-25  IEC:2001+A1:2012 – 7 –
ELECTROMAGNETIC COMPATIBILITY (EMC) –

Part 4-25: Testing and measurement techniques –
HEMP immunity test methods for equipment and systems

1 Scope
This part of IEC 61000 describes the immunity test levels and related test methods for
electrical and electronic equipment and systems exposed to high-altitude electromagnetic
pulse (HEMP) environments. It defines ranges of immunity test levels and establishes test
procedures. Specifications for test equipment and instrumentation test set-up, test procedures,
pass/fail criteria, and test documentation requirements are also defined by this standard.
These tests are intended to demonstrate the immunity of electrical and electronic equipment
when subjected to HEMP radiated and conducted electromagnetic disturbances. For radiated
disturbance immunity tests, specifications are defined in this standard both for small test
facilities and large HEMP simulators.
This part of IEC 61000 defines specifications for laboratory immunity tests. On-site tests
performed on equipment in the final installation to verify immunity are also specified. These
verification tests use the same specifications as laboratory tests, except for the climatic
environmental specifications.
The objective of this part of IEC 61000 is to establish a common and reproducible basis for
evaluating the performance of electrical and electronic equipment, when subjected to HEMP
radiated environments and the associated conducted transients on power, antenna, and
input/output (I/O) signal and control lines.
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 60050(161), International Electrotechnical Vocabulary – Chapter 161: Electromagnetic
compatibility
IEC 60038, IEC standard voltages
IEC 60068-1:1988, Environmental testing – Part 1: General and guidance
IEC 61000-2-5, Electromagnetic compatibility (EMC) – Part 2: Environment – Section 5:
Classification of electromagnetic environments. Basic EMC publication
IEC 61000-2-9, Electromagnetic compatibility (EMC) – Part 2: Environment – Section 9:
Description of HEMP environment – Radiated disturbance. Basic EMC publication
IEC 61000-2-10:1998, Electromagnetic compatibility (EMC) – Part 2-10: Environment –
Description of HEMP environment – Conducted disturbance
IEC 61000-2-11, Electromagnetic compatibility (EMC) – Part 2: Environment – Section 11:
Classification of HEMP environments. Basic EMC publication

– 8 – 61000-4-25  IEC:2001+A1:2012
IEC 61000-4-4, Electromagnetic compatibility (EMC) – Part 4: Testing and measurement
techniques – Section 4: Electrical fast transient/burst immunity test. Basic EMC Publication
IEC 61000-4-5, Electromagnetic compatibility (EMC) – Part 4: Testing and measurement
techniques – Section 5: Surge immunity test
IEC 61000-4-11, Electromagnetic compatibility (EMC) – Part 4: Testing and measurement
techniques – Section 11: Voltage dips, short interruptions and voltage variations immunity tests
IEC 61000-4-12, Electromagnetic compatibility (EMC) – Part 4: Testing and measurement
techniques – Section 12: Oscillatory waves immunity test
IEC 61000-4-13, Electromagnetic compatibility (EMC) – Part 4-13: Testing and measurement
techniques – Harmonics and interharmonics including mains signalling at a.c. power port, low
frequency immunity tests – Basic EMC Publication
IEC 61000-4-18, Electromagnetic compatibility (EMC) – Part 4-18: Testing and measurement
techniques – Damped oscillatory wave immunity test
IEC 61000-4-20, Electromagnetic compatibility (EMC) – Part 4-20: Testing and measurement
techniques – Emission and immunity testing in transverse electromagnetic (TEM) waveguides
IEC 61000-4-33, Electromagnetic compatibility (EMC) – Part 4-33: Testing and measurement
techniques – Measurement methods for high-power transient parameters
IEC 61000-5-3, Electromagnetic compatibility (EMC) – Part 5-3: Installation and mitigation
guidelines – HEMP protection concepts
IEC 61000-5-4/TR, Electromagnetic compatibility (EMC) – Part 5: Installation and mitigation
guidelines – Section 4: Immunity to HEMP – Specifications for protective devices against
HEMP radiated disturbance. Basic EMC Publication
IEC 61024-1, Protection of structures against lightning – Part 1: General principles
ISO 7137, Aircraft – Environmental conditions and test procedures for airborne equipment
3 Definitions
For the purpose of this part of IEC 61000, the following definitions apply.
3.1
compatibility level
specified electromagnetic disturbance level used as a reference level for co-ordination in the
setting of emission and immunity limits
[IEV 161-03-10]
3.2
coupling (HEMP)
interaction of electromagnetic fields with a system to produce currents and voltages on system
surfaces and cables
3.3
coupling clamp
device of defined dimensions and characteristics for common mode coupling of the disturbance
signal to the circuit under test without any galvanic connection to it
___________
To be published
61000-4-25  IEC:2001+A1:2012 – 9 –
3.4
coupling network
electrical circuit for the purpose of transferring energy from one circuit to another
3.5
decoupling network
electrical circuit for the purpose of preventing over-voltages applied to the EUT from affecting
other devices, equipment or systems, which are not under test
3.6
degradation (of performance)
undesired departure in the operational performance of any device, equipment or system from
its intended performance
NOTE The term “degradation” can apply to a temporary or permanent failure.
[IEV 161-01-19]
3.7
electromagnetic disturbance
any electromagnetic phenomenon which may degrade the performance of a device, equipment
or system
[IEV 161-01-05, modified]
3.8
electromagnetic interference
degradation of the performance of a device, transmission channel or system caused by an
electromagnetic disturbance
[IEV 161-01-06]
3.9
electromagnetic susceptibility
inability of a device, equipment or system to perform without degradation in the presence of an
electromagnetic disturbance
NOTE Susceptibility is a lack of immunity.
[IEV 161-01-21]
3.10
EUT (equipment under test)
the equipment under test can be a single unit or multiple units interconnected by cables, data
links, etc.
NOTE Multiple units interconnected by cables, etc. are also called a system [see 3.27 below].
3.11
fast Fourier transform
FFT
mathematical procedure for rapidly computing the direct or inverse Fourier transform of a time
m
domain signal or of a frequency domain spectrum, respectively. It requires 2 (m = integer)
data points that are equally spaced in time or frequency, and involves much less computation
time than a standard discrete Fourier transform (DFT)
3.12
ground reference plane
flat conductive surface, whose potential is used as a common reference
[IEV 161-04-36]
– 10 – 61000-4-25  IEC:2001+A1:2012
3.13
HV transmission line
power line with a nominal a.c. system voltage equal to or greater than 100 kV
3.14
short circuit current
I
sc
current resulting from an abnormal connection of relatively low resistance between two points
of different potentials in a circuit
3.15
immunity (to a disturbance)
ability of a device, equipment or system to perform without degradation in the presence of an
electromagnetic disturbance
[IEV 161-01-20]
3.16
immunity level
maximum level of a given electromagnetic disturbance incident on a particular device,
equipment or system for which it remains capable of operating at a required degree of
performance
[IEV 161-03-14]
3.17
immunity test level
value of an influencing electromagnetic quantity specified for an immunity test
NOTE It is to be noted that the text of this definition is the same as for severity level. A test standard can specify
several severity levels according to different immunity levels.
3.18
large HEMP simulator
transient electromagnetic pulse test facility with a test volume sufficiently large to test objects
with cubical dimensions equal to or greater than 1 m × 1 m × 1 m
3.19
LV (low-voltage) power circuit
power circuit with a nominal a.c. voltage between 120 V and 1 000 V
NOTE The standard voltages in this voltage range are presented in IEC 60038.
3.20
MV (medium voltage) distribution power line
power line with a nominal a.c. voltage above 1 kV and not exceeding 35 kV used to distribute
power within a local area
NOTE The standard voltages in this voltage range are presented in IEC 60038.
3.21
point-of-entry
port-of-entry
PoE
the physical location (point/port) on the electromagnetic barrier, where EM energy may enter or
exit a topological volume, unless an adequate PoE protective device is provided. A PoE is not
limited to a geometrical point. PoEs are classified as aperture PoEs or conductor PoEs,
according to the type of penetration. They are also classified as architectural, mechanical,
structural or electrical PoEs, according to the architectural engineering discipline in which they
are usually encountered
61000-4-25  IEC:2001+A1:2012 – 11 –
3.22
pulse width
time interval between the points on the leading and trailing edges of a pulse at which the
instantaneous value is 50 % of the peak pulse amplitude
3.23
rise time (of a pulse)
interval of time between the instants at which the instantaneous value of a pulse first reaches a
specified lower value and then a specified upper value
[IEV 161-02-05]
NOTE In this standard, the lower value is ten (10) percent of the peak, and the upper value is ninety (90) percent
of the peak value
3.24
severity level
value of an influencing electromagnetic quantity specified for an immunity test
NOTE It is to be noted that the text of this definition is the same as for immunity test level. A test standard can
specify several severity levels according to different immunity levels.
3.25
small radiated test facility
laboratory transient electromagnetic pulse test facility such as a TEM cell with a test volume
sufficiently large to test objects with cubical dimensions less than 1 × 1 × 1 meter
3.26
surge protection device (SPD)
device to suppress line conducted overvoltages and currents
NOTE Examples are surge suppressors defined in IEC 61024-1.
3.27
system
multiple equipment or electrical units connected by cables, data links, etc.
3.28
test volume
volume in which the incident electromagnetic fields meet, or exceed, the required strength and
field uniformity requirements.
3.29
transient
phenomenon which varies between two consecutive steady states during a time interval short
compared with the time-scale of interest
[IEV 161-02-01]
3.30
open circuit voltage
V
oc
voltage between points in a circuit where one of the points was created by opening or breaking
the circuit
4 General
The nuclear high-altitude electromagnetic pulse test consists of two major parts: radiated
immunity testing and conducted immunity testing. The radiated immunity test is performed for
the purpose of demonstrating that the equipment under test has the ability to continue
functioning when exposed to radiated HEMP fields. Similarly, the conducted immunity test is

– 12 – 61000-4-25  IEC:2001+A1:2012
performed for the purpose of demonstrating that the equipment under test will not be adversely
affected by exposure to conducted HEMP transients. These transients are current and voltage
pulses on conductors (wires, cables) that are connected to the equipment. In general,
conducted HEMP transients induced in power and telecom lines are often the most severe
threats to equipment. The immunity tests described in this standard involve hazardous
voltages. High-voltage precautions will be necessary to protect the health and safety of test
personnel.
5 Immunity tests and immunity test levels
5.1 Introduction
This standard has been developed to specify the HEMP immunity test for electrical or
electronic equipment and systems. The intent is to allow manufacturers to qualify equipment
early in the design cycle, and to use many of the same IEC laboratory immunity tests that are
already prescribed for other EMC purposes.
5.2 Immunity tests
HEMP immunity tests consist of two major types: radiated immunity tests and conducted
immunity tests. For the purpose of this standard, the term "electronic equipment" denotes an
apparatus that performs a specific function. This could be a small computer or a telephone.
Some equipment (for example, a computer connected to additional peripherals such as control
boards to monitor processes in a factory) may be considered as part of a larger system. Often,
electronic equipment are relatively small – on the order of 1 m x 1 m x 1 m or smaller. It is
expected that most of the tests on such small equipment will be performed in laboratories
using current injection simulators and TEM cells.
For HEMP (and EMC) tests, size can be an important factor, since very large systems may be
difficult to test, especially by radiated fields. In general, radiated field tests on systems and
large equipment with dimensions greater than 1 m on a side will require a large HEMP
simulator. One aspect of HEMP testing that is different from other kinds of EMC testing is that
there are several large (∼10 m high) early-time (t < 1 µs) HEMP simulators throughout the
world. It is possible to expose some systems and large equipment to the early-time HEMP
threat by reproducing the pulsed electric and magnetic fields. These simulators are also useful
in verifying that equipment designed and tested for HEMP survival at the equipment level, will
work properly when integrated into a complete system.
5.3 Immunity test levels
This standard defines electromagnetic disturbances that represent those which could result at
the equipment ports due to a high-altitude nuclear event. These electromagnetic disturbances
will be the result of the radiated and conducted HEMP environments, as modified by any
protection elements. These electromagnetic disturbances are described in IEC 61000-2-9,
IEC 61000-2-10 and IEC 61000-2-11. The rationale for the immunity test levels and threat
reductions due to protection elements and probable flashovers are described in annex A.
5.4 Radiated disturbance tests
5.4.1 Radiated immunity test levels
The radiated immunity test levels described below involve only the early time radiated fields.
Testing for the intermediate-time and late-time HEMP fields are not required. Information
regarding the selection of the immunity test levels is given in annex A. The peak values of the
early-time electric field, E , for selected immunity test levels are listed in table 1.
peak
61000-4-25  IEC:2001+A1:2012 – 13 –
Table 1 – Radiated immunity test levels defined in the present standard
b
Immunity test level Test required for equipment and E-field peak value
a
systems with the following protection
E (kV/m)
peak
R1 Concept 4 0,5
R2 Intermediate value 1
R3 Intermediate value 2
R4 Concepts 2A, 2B, 3 5
R5 Intermediate value 10
R6 Intermediate value 20
R7 Concepts 1A, 1B 50
RX Special applications X
a
The protection concepts are described in IEC 61000-5-3
b
According to IEC 61000-2-11, table 2

5.4.2 Radiated immunity test specifications
In the absence of an object in the simulator, the electric field in the test volume is a wave
comparable to a quasi-plane wave, with a double exponential pulse time history described by a
2,5/25 ns wave, i.e. a unipolar wave with a 10 %-90 % rise time of 2,5 ns and a pulse width
equal to 25 ns. This waveform is given by the equation below.
−βt −αt
E(t) = E × k × (e − e )     V/m (1)
peak
where
8 -1 7 -1
α = 6,0 × 10 s , β = 4,0 × 10 s , and
k = 1,3.
E is the peak value of the electric field in volts per meter.
peak
NOTE E is the immunity test level selected from table 1.
peak
t is the time in seconds.
The frequency-domain spectral magnitude for equation (1) is given by
E × k ×(α − β )
peak
E( f ) =  (V/m/Hz) (2)
[((2 πf )² + α²) ((2 πf )² + β ²)]
where
f is the frequency in hertz.
For the waveform parameters given above, the frequency-domain spectral magnitude of
equation (2) is shown in figure 1.

– 14 – 61000-4-25  IEC:2001+A1:2012
1E–7
1E–8
1E–9
1E–10
0,1 1 10 100
Frequency  MHz
IEC  2168/01
Figure 1 – Frequency domain spectral magnitude between 100 kHz and 300 MHz.
5.4.3 Small radiated test facilities
Small test facilities can more easily meet the desired field specifications with smaller
tolerances in parameter variations than the large HEMP simulators. These small facilities will
be used primarily to test relatively small equipment. Tolerances for the early-time HEMP pulse
waveform over the entire parallelepiped test volume of the small test facility shall be as follows.
– The ratio of peak electric field to the peak magnetic field shall be equal to 377 Ω ± 50 Ω.
– The rise time between 10 % and 90 % of the peak value shall be within the range of 2,0 ns
and 2,5 ns.
– The electric field shall be continuously increasing during the 10 % and 90 % rise time.
– The pulse width (the time duration between points on the leading and trailing edges of the
) shall be within the range of 25 ns and 30 ns.
pulse at 50 % of E
peak
– The magnitude of any pre-pulse on the electric field shall be equal to or less than 7 % of
the magnitude of the peak field.
– Electric field reflections from the terminator of the simulator shall be less than 10 %.
– Fluctuations in the smoothed frequency spectrum of the electric field at the centre of the
test volume (see 5.4.5) shall not be larger than ±3 dB compared to theoretical spectrum
given by equation (2) in the bandwidth between 100 kHz and 300 MHz.
– At the time of the peak value of the simulated fields, other non-principal electromagnetic
components shall be smaller than 10 % of the peak value of the simulated field.
– The peak electric field shall be uniform in the test volume to within the following criteria: the
peak electric field within the test volume shall be within the range of E and E +6 dB.

peak peak
– To evaluate the field tolerances, electric and magnetic field measurements at the centre
and the eight corners of the test volume shall be performed in the absence of the EUT.

5.4.4 Large HEMP simulators
Large HEMP simulators can be used to test large equipment and complete systems. Due to the
variety of such simulators, there are wide ranges of rise times, pulse widths and amplitudes of
the fields produced by these devices. Consequently, large HEMP simulators are divided into
two types, based on their radiated field behaviour: types I and II. Generally, type I simulators
provide a shorter rise time and pulse width than do the type II simulators. A pre-test analysis is
required for tests with type II simulators, since these test facilities do not meet the radiated
immunity specifications given in 5.4.2.

E (f)/E
 
peak
(1/Hz)
61000-4-25  IEC:2001+A1:2012 – 15 –
The response of an electrical component within a system due to HEMP depends not only on
the pulse shape (or frequency domain spectrum), but also on the coupling and penetration
mechanism that the HEMP signals use in propagating from the external portions of the system
to the component. In some classes of systems (i.e., small systems with no long conducting
appendages, like a mobile telephone), the HEMP coupling will be dominated by aperture
penetrations – an inherently high frequency mechanism. Consequently, the type I simulators
having a larger high frequency spectral content would be desirable for testing. However, in
other types of systems containing longer external conductors (a HF radio, for example), the
dominant HEMP response will result from the field coupling to the antenna. Thus, the type II
simulators with a slower rise and longer pulse width would likely be adequate for testing these
particular systems.
The fact that different systems can react to different components of the incident HEMP
environment illustrates the point that a pre-test analysis program is necessary for type II
simulators. The pre-test analysis shall be performed to determine exactly how the type II
simulated fields will couple to the system, and to assess the adequacy of the type II simulators
for performing the immunity test. The adequacy of the test shall be demonstrated by comparing
the interaction and coupling results of the simulated fields with those of the theoretical pulse
described in 5.4.2.
5.4.4.1 Large HEMP simulators − type I
For testing in the type I simulators, the peak electric field, E , shall be chosen from table 1
peak
corresponding to the immunity test level selected for the test. Tolerances for the early-time
HEMP pulse over the entire parallelepiped test volume of the simulator shall be as follows.
– The ratio of peak electric field to the peak magnetic field shall be equal to 377 Ω ± 50 Ω.
– The rise time between 10 % and 90 % of the peak value shall be 2,5 ns ± 0,5 ns.
– The electric field shall be continuously increasing during the 10 % and 90 % rise time.
– The pulse width (the time duration between points on the leading and trailing edges of the
) shall be within the range of 25 ns and 75 ns.
pulse at 50 % of E
peak
– The magnitude of any pre-pulse on the electric field shall be equal to or less than 7 % of
the magnitude of the peak field.
– Electric field reflections from the terminator of the simulator shall be less than 10 %.
– Fluctuations in the smoothed frequency spectrum of the electric field at the centre of the
test volume (see 5.4.5) shall not be larger than ±10 dB compared to theoretical spectrum
given by equation (2) in the bandwidth between 1 MHz and 200 MHz.
– The peak electric field shall be uniform in the test volume to within the following criteria: the
peak electric field within the test volume shall be within the range of E and E + 6 dB.

peak peak
– To evaluate the field tolerances, electric and magnetic field measurements at the centre
and the eight corners of the test volume shall be performed in the absence of the EUT.
5.4.4.2 Large HEMP simulators − type II
A pre-test analysis is required for tests with type II simulators since these test facilities do not
meet the radiated immunity specifications given in 5.4.2.
The specifications of type II large simulators are the same as type I, except for rise time, pulse
width, and frequency spectrum specification, which are as follows:
– The rise time between 10 % and 90 % of the peak value shall be within the range of 2 ns
and 10 ns.
– The pulse width (the time duration between points on the leading and trailing edges of the
pulse at 50 % of E ) shall be within the range of 25 ns and 500 ns.
peak
– 16 – 61000-4-25  IEC:2001+A1:2012
– Fluctuations in the smoothed frequency spectrum of the electric field at the centre of the
test volume (see 5.4.5) shall not be larger than ±10 dB compared to the theoretical
spectrum given by equation (2) in the bandwidth between 1 MHz and 100 MHz.
5.4.5 Frequency domain spectrum requirements
In addition to the requirements on the transient fields of the HEMP simulator, the following
requirements shall be placed on the frequency domain spectrum of the simulator fields:
a) The frequency spectrum shall be computed using a uniformly sampled transient waveform
having 4 096 samples between the starting time of 0 and the ending time of 2 µs. A 2 048
point complex-valued frequency spectrum shall be calculated using an FFT (fast Fourier
tran
...