SIST EN IEC 61340-4-7:2025
(Main)Electrostatics - Part 4-7: Standard test methods for specific applications - Ionization (IEC 61340-4-7:2025)
Electrostatics - Part 4-7: Standard test methods for specific applications - Ionization (IEC 61340-4-7:2025)
This part of IEC 61340 provides test methods and procedures for evaluating and selecting air ionization equipment and systems (ionizers).
This document establishes measurement techniques, under specified conditions, to determine offset voltage (ion balance) and decay (charge neutralization) time for ionizers.
This document does not include measurements of electromagnetic interference (EMI), or the use of ionizers in connection with ordnance, flammables, explosive items or electrically initiated explosive devices.
As contained in this document, the test methods and test conditions can be used by manufacturers of ionizers to provide performance data describing their products. Users of ionizers are urged to modify the test methods and test conditions for their specific application in order to qualify ionizers for use, or to make periodic verifications of ionizer performance. The user will decide the extent of the data required for each application.
See Annex A for information regarding theoretical background and additional information on the standard test method for the performance of ionizers.
CAUTION: Procedures and equipment described in this document can expose personnel to hazardous electrical and non-electrical conditions. Users of this document are responsible for selecting equipment that complies with applicable laws, regulatory codes and both external and internal policy. Users are cautioned that this document cannot replace or supersede any requirements for personnel safety. See Annex C for safety considerations.
Elektrostatik - Teil 4-7: Standard-Prüfverfahren für spezielle Anwendungen – Ionisation (IEC 61340-4-7:2025)
Electrostatique - Partie 4-7: Méthodes d'essai normalisées pour des applications spécifiques - Ionisation (IEC 61340-4-7:2025)
L'IEC 61340-4-7:2025 fournit des méthodes et des procédures d'essai pour évaluer et choisir le matériel et les systèmes d'ionisation de l'air (ioniseurs). Le présent document établit des techniques de mesure, dans des conditions spécifiées, destinées à déterminer la tension de décalage (équilibre ionique) et le temps de décroissance (neutralisation des charges) pour les ioniseurs. Le présent document ne traite pas des mesurages des brouillages électromagnétiques (EMI, Electromagnetic Interference) ni de l'emploi d'ioniseurs en relation avec des éléments pyrotechniques, inflammables, explosifs ou des appareils explosifs amorcés électriquement. Les méthodes d'essai et les conditions d'essai spécifiées dans le présent document peuvent être utilisées telles quelles par les fabricants d'ioniseurs afin de fournir des données de performance pour la description de leurs produits. Les utilisateurs d'ioniseurs sont encouragés à modifier les méthodes d'essai et les conditions d'essai de leur application spécifique afin de qualifier les ioniseurs pour l'utilisation ou d'effectuer des vérifications périodiques de la performance des ioniseurs. Il revient à l'utilisateur de déterminer la quantité de données exigées pour chaque application.
Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente:
a) une NOTE 3 a été ajoutée à la Figure 5 afin d'expliciter qu'un seul émetteur à alternance de polarité +/- est utilisé pour les barres et les grilles en courant alternatif;
b) à l'Annexe B, l'erreur relative aux appareils de mesure à été mise à jour pour prendre en compte la résolution du voltmètre.
Elektrostatika - 4-7. del: Standardne preskusne metode za posebno uporabo - Ionizacija (IEC 61340-4-7:2025)
Ta del standarda IEC 61340 določa preskusne metode in postopke za vrednotenje in izbiranje opreme in sistemov za ionizacijo zraka (ionizatorjev).
Ta dokument vzpostavlja merilne tehnike pod določenimi pogoji za določanje napetostnega premika (ionsko ravnovesje) in čas upadanja (nevtralizacija naboja) za ionizatorje.
Ta dokument ne vključuje meritev elektromagnetnih motenj (EMI) ali uporabe ionizatorjev v zvezi z ubojnimi sredstvi, vnetljivimi snovmi, eksplozivnimi predmeti ali elektronsko sproženimi eksplozivnimi napravami.
Kot je zapisano v tem dokumentu, lahko preskusne metode in preskusne pogoje uporabljajo proizvajalci ionizatorjev, da podajo podatke o delovanju, ki opisujejo njihove proizvode. Uporabnike ionizatorjev se spodbuja, da preskusne metode in preskusne pogoje prilagodijo svoji specifični uporabi, da kvalificirajo ionizatorje za uporabo ali da redno preverjajo delovanje ionizatorjev. Uporabnik določi obseg podatkov, potrebnih za vsako uporabo.
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
01-november-2025
Nadomešča:
SIST EN 61340-4-7:2017
Elektrostatika - 4-7. del: Standardne preskusne metode za posebno uporabo -
Ionizacija (IEC 61340-4-7:2025)
Electrostatics - Part 4-7: Standard test methods for specific applications - Ionization (IEC
61340-4-7:2025)
Elektrostatik - Teil 4-7: Standard-Prüfverfahren für spezielle Anwendungen – Ionisation
(IEC 61340-4-7:2025)
Electrostatique - Partie 4-7: Méthodes d'essai normalisées pour des applications
spécifiques - Ionisation (IEC 61340-4-7:2025)
Ta slovenski standard je istoveten z: EN IEC 61340-4-7:2025
ICS:
17.220.99 Drugi standardi v zvezi z Other standards related to
elektriko in magnetizmom electricity and magnetism
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
EUROPEAN STANDARD EN IEC 61340-4-7
NORME EUROPÉENNE
EUROPÄISCHE NORM October 2025
ICS 17.200.99; 29.020 Supersedes EN 61340-4-7:2017
English Version
Electrostatics - Part 4-7: Standard test methods for specific
applications - Ionization
(IEC 61340-4-7:2025)
Electrostatique - Partie 4-7 : Méthodes d'essai normalisées Elektrostatik - Teil 4-7: Standard-Prüfverfahren für spezielle
pour des applications spécifiques - Ionisation Anwendungen - Ionisation
(IEC 61340-4-7:2025) (IEC 61340-4-7:2025)
This European Standard was approved by CENELEC on 2025-09-23. CENELEC members are bound to comply with the CEN/CENELEC
Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.
Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC
Management Centre or to any CENELEC member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the
same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,
Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the
Netherlands, Norway, Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Türkiye and the United Kingdom.
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2025 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.
Ref. No. EN IEC 61340-4-7:2025 E
European foreword
The text of document 101/739/FDIS, future edition 3 of IEC 61340-4-7, prepared by TC 101
"Electrostatics" was submitted to the IEC-CENELEC parallel vote and approved by CENELEC as
The following dates are fixed:
• latest date by which the document has to be implemented at national (dop) 2026-10-31
level by publication of an identical national standard or by endorsement
• latest date by which the national standards conflicting with the (dow) 2028-10-31
document have to be withdrawn
This document supersedes EN 61340-4-7:2017 and all of its amendments and corrigenda (if any).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CENELEC shall not be held responsible for identifying any or all such patent rights.
Any feedback and questions on this document should be directed to the users’ national committee. A
complete listing of these bodies can be found on the CENELEC website.
Endorsement notice
The text of the International Standard IEC 61340-4-7:2025 was approved by CENELEC as a
European Standard without any modification.
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications
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.
NOTE 1 Where an International Publication has been modified by common modifications, indicated by (mod),
the relevant EN/HD applies.
NOTE 2 Up-to-date information on the latest versions of the European Standards listed in this annex is available
here: www.cencenelec.eu.
Publication Year Title EN/HD Year
IEC 61010-1 - Safety requirements for electrical equipment for EN 61010-1 -
measurement, control, and laboratory use - Part 1:
General requirements
IEC 61340-4-7 ®
Edition 3.0 2025-08
INTERNATIONAL
STANDARD
Electrostatics -
Part 4-7: Standard test methods for specific applications - Ionization
ICS 17.200.99; 29.020 ISBN 978-2-8327-0643-5
IEC 61340-4-7:2025-08(en)
IEC 61340-4-7:2025 © IEC 2025
CONTENTS
FOREWORD . 3
INTRODUCTION . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 Test fixture and instrumentation . 8
5 Specific requirements for equipment categories . 10
5.1 Specific requirements for all ionization equipment . 10
5.2 Room ionization . 11
5.3 Laminar flow hood ionization . 13
5.4 Worksurface ionization . 15
5.5 Compressed gas ionizers – Guns and nozzles . 17
Annex A (informative) Theoretical background and additional information on the
standard test method for the performance of ionizers . 19
A.1 Introductory remarks . 19
A.2 Air ions . 19
A.3 Mobility and ion current . 19
A.4 Neutralization current . 20
A.5 Neutralization rate . 20
A.6 Ion depletion and field suppression . 20
A.7 Charged plate monitor and charge neutralization . 21
A.8 Relationship between charged plate monitor decay time and actual object . 21
A.9 Offset voltage . 21
A.10 Preparation of test area . 22
A.11 Ion transport in airflow . 22
A.12 Obstruction of airflow around the charged plate monitor . 22
A.13 Effect of "air blanket" . 23
A.14 Sources of measurement error . 23
A.14.1 Typical decay time variability . 23
A.14.2 Plate isolation . 23
A.14.3 Charging voltage . 23
A.14.4 Materials near the plate . 23
A.14.5 Other field-producing devices in test area . 23
A.14.6 Effect of offset voltage on decay time . 24
A.15 Importance of ionization equipment maintenance . 24
Annex B (normative) Method of measuring the capacitance of an isolated conductive
plate . 25
B.1 Method . 25
B.2 Equipment . 25
B.3 Procedure . 25
B.4 Example. 26
B.5 Sources of error . 26
B.5.1 Measuring equipment . 26
B.5.2 Poor plate isolation . 27
B.5.3 Objects in the environment . 27
B.5.4 Stray capacitance . 28
Annex C (informative) Safety considerations . 29
IEC 61340-4-7:2025 © IEC 2025
C.1 General . 29
C.2 Electrical . 29
C.3 Ozone . 29
C.4 Radioactive . 29
C.5 X-ray . 29
C.6 Installation . 29
Bibliography . 30
Figure 1 – Charged plate monitor components for non-contacting plate measurement . 9
Figure 2 – Charged plate monitor components for contacting plate measurement . 9
Figure 3 – Conductive plate detail of the non-contacting CPM . 9
Figure 4 – Conductive plate detail of the voltage follower CPM . 10
Figure 5 – Test locations for room ionization – AC bars, grids and DC bar systems . 12
Figure 6 – Test locations for room ionization – Single polarity emitter systems . 12
Figure 7 – Test locations for room ionization – Two DC-line systems . 13
Figure 8 – Test locations for room ionization – Pulsed DC emitter systems . 13
Figure 9 – Test locations for vertical laminar flow hood – Top view . 14
Figure 10 – Test locations for vertical laminar flow hood – Side view . 14
Figure 11 – Test locations for horizontal laminar flow hood – Top view . 15
Figure 12 – Test locations for horizontal laminar flow hood – Side view . 15
Figure 13 – Test locations for benchtop ionizer – Top view . 16
Figure 14 – Test locations for benchtop ionizer – Side view . 16
Figure 15 – Test locations for overhead ionizer – Top view . 17
Figure 16 – Test locations for overhead ionizer – Side view . 17
Figure 17 – Test locations for compressed gas ionizer (gun or nozzle) – Side view . 18
Table 1 – Test set-ups and test locations and points (TP) . 11
Table B.1 – Example measurement data . 26
IEC 61340-4-7:2025 © IEC 2025
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
Electrostatics -
Part 4-7: Standard test methods for specific applications - Ionization
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
misinterpretation by any end user.
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
members of its technical committees and IEC National Committees for any personal injury, property damage or
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) IEC draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). IEC takes no position concerning the evidence, validity or applicability of any claimed patent rights in
respect thereof. As of the date of publication of this document, IEC had not received notice of (a) patent(s), which
may be required to implement this document. However, implementers are cautioned that this may not represent
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 61340-4-7 has been prepared by IEC technical committee 101: Electrostatics. It is an
International Standard.
This third edition cancels and replaces the second edition published in 2017. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) in Figure 5, a NOTE 3 was added to clarify that for AC bars and grids, a single emitter
alternating between +/− polarity is used;
b) in Annex B, the relative error for measurement equipment was updated to include the
consideration for the resolution of the voltmeter.
IEC 61340-4-7:2025 © IEC 2025
The text of this International Standard is based on the following documents:
Draft Report on voting
101/739/FDIS 101/744/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.
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 in the IEC 61340 series, published under the general title Electrostatics, 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.
IEC 61340-4-7:2025 © IEC 2025
INTRODUCTION
Grounding is the primary method used to limit static charge when protecting electrostatic
discharge sensitive items in the work environment. However, grounding methods are not
effective in removing static charges from the surfaces of non-conductive (insulative) or isolated
(ungrounded) conductive materials. Air ionization techniques, by means of ionizer systems, can
be utilized to reduce this charge.
The preferred way of evaluating the ability of an ionizer to neutralize a static charge is to directly
measure the rate of charge decay. Charges to be neutralized can be located on insulators as
well as on isolated conductors. It is difficult to charge an insulator reliably and repeatably.
Charge neutralization is more easily evaluated by measuring the rate of decay of the voltage of
an isolated conductive plate. The measurement of this decay should not interfere with or change
the nature of the actual decay. Four practical methods of air ionization are addressed in this
document:
a) radioactive emission;
b) high-voltage corona from AC electric fields;
c) high-voltage corona from DC electric fields;
d) soft X-ray emission.
This part of IEC 61340 provides test methods and procedures that can be used when evaluating
ionization equipment. The objective of the test methods is to generate meaningful, reproducible
data. The test methods are not meant to be a recommendation for any particular ionizer
configuration. The wide variety of ionizers, and the environments within which they are used,
will often require test methods different from those described in this document. Users of this
document should be prepared to adapt the test methods as required to produce meaningful data
in their own application of ionizers.
Similarly, the test conditions chosen in this document do not represent a recommendation for
acceptable ionizer performance. There is a wide range of item sensitivities to static charge.
There is also a wide range of environmental conditions affecting the operation of ionizers.
Performance specifications should be agreed upon between the user and manufacturer of the
ionizer in each application. Users of this document should be prepared to establish reasonable
performance requirements for their own application of ionizers.
Annex B provides a method for measuring capacitance of the isolated conductive plate.
IEC 61340-4-7:2025 © IEC 2025
1 Scope
This part of IEC 61340 provides test methods and procedures for evaluating and selecting air
ionization equipment and systems (ionizers).
This document establishes measurement techniques, under specified conditions, to determine
offset voltage (ion balance) and decay (charge neutralization) time for ionizers.
This document does not include measurements of electromagnetic interference (EMI), or the
use of ionizers in connection with ordnance, flammables, explosive items or electrically initiated
explosive devices.
As contained in this document, the test methods and test conditions can be used by
manufacturers of ionizers to provide performance data describing their products. Users of
ionizers are urged to modify the test methods and test conditions for their specific application
in order to qualify ionizers for use, or to make periodic verifications of ionizer performance. The
user will decide the extent of the data required for each application.
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, Safety requirements for electrical equipment for measurement, control, and
laboratory use - Part 1: General requirements
3 Terms and definitions
For the purposes of this document, the following terms and definitions 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
3.1
air conductivity
ability of air to conduct (pass) an electric current under the influence of an electric field
3.2
air ions
molecular clusters of about ten molecules (water, impurities, etc.) bound by polarization forces
to a singly charged oxygen or nitrogen molecule
3.3
charge decay
decrease or neutralization or both of a net electrostatic charge
IEC 61340-4-7:2025 © IEC 2025
3.4
charged plate monitor
CPM
instrument using a charged metal plate of a defined capacitance and geometry which is
discharged in order to measure charge dissipation and neutralization properties of products or
materials
3.5
compressed gas ionizer
ionization device that can be used to neutralize charged surfaces or remove surface particles
or both with pressurized gas
Note 1 to entry: This type of ionizer can be used to ionize the gas within production equipment.
3.6
corona
production of positive or negative ions by a very localized high electric field
Note 1 to entry: The field is normally established by applying a high voltage to a conductor in the shape of a sharp
point or wire.
3.7
decay time
time necessary for a voltage (due to an electrostatic charge) to decay from an initial value to
some chosen final value
3.8
emitter
conducting sharp object, usually a needle or wire, which will cause a corona discharge when
kept at a high potential
3.9
horizontal laminar flow
non-turbulent airflow in a horizontal direction
3.10
ionizer
device designed to generate positive or negative or both air ions
3.11
isolated conductor
conductor that has sufficiently high resistance to ground that significant charge dissipation is
prevented within the timescale of interest
3.12
laminar flow hood ionization
device or system that provides local area ionization coverage in vertical or horizontal laminar
flow hoods or benches
3.13
offset voltage
ion balance
observed voltage on the isolated conductive plate of a charged plate monitor (CPM) that has
been placed in an ionized environment
3.14
peak offset voltage
for pulsed ionizers, maximum value of the offset voltage for each polarity, as the ionizer cycles
between positive and negative ion outputs
IEC 61340-4-7:2025 © IEC 2025
3.15
room ionization
ionization system that provides large area coverage with air ions
3.16
worksurface ionization
ionization device or system used to control static charges on a worksurface
Note 1 to entry: Worksurface ionizers include benchtop ionizers, overhead worksurface ionizers and laminar flow
hood ionizers.
3.17
vertical laminar flow
non-turbulent airflow in a vertical direction
4 Test fixture and instrumentation
WARNING – Procedures and equipment described in this document can expose personnel to
hazardous electrical and non-electrical conditions. Users of this document are responsible for
selecting equipment that complies with applicable laws, regulatory codes and both external and
internal policy. Users are cautioned that this document cannot replace or supersede any
requirements for personnel safety. See Annex C for safety considerations.
The instrument described in this document to make performance measurements on air
ionization equipment is the charged plate monitor (CPM); refer to Figure 1 and Figure 2. The
conductive plate shall be (15,0 ± 0,1) cm × (15,0 ± 0,1) cm and the total capacitance of the test
circuit, with plate, while the instrument is in its normal operating mode, shall be 20 pF ± 2 pF
as measured per Annex B. See Figure 3 and Figure 4. The instrument described in this
document can also be used for compliance verification of air ionizers.
For the isolated conductive plate design shown in Figure 3, there shall be no objects, grounded
or otherwise, closer than dimension "A" of the conductive plate, except the supporting insulators
or plate voltage contacts, as shown in Figure 3 (refer to Annex B). For the conductive plate
assembly shown in Figure 4, there shall be no objects, grounded or otherwise, within 2,5 cm of
the plate assembly in any direction, other than a support structure (e.g. a tripod) located below
the ground plate of the assembly.
The conductive plate, when charged to the desired test voltage, shall not decay by more than
10 % of the test voltage within 5 min, in the absence of ionization.
The voltage on the conductive plate shall be monitored with a response time sufficient to
accurately measure changing plate voltages. Changing plate voltages are a function of the
ionization technology type being monitored.
For safety reasons (see Clause C.1), the voltage source used to charge the conductive plate
should be current limited. The voltage source used to charge the conductive plate shall meet
the requirements of IEC 61010-1.
IEC 61340-4-7:2025 © IEC 2025
NOTE See Figure 3 for a detailed drawing of the non-contacting CPM.
Figure 1 – Charged plate monitor components for non-contacting plate measurement
NOTE See Figure 4 for a detailed drawing of the contacting CPM.
Figure 2 – Charged plate monitor components for contacting plate measurement
Figure 3 – Conductive plate detail of the non-contacting CPM
IEC 61340-4-7:2025 © IEC 2025
Figure 4 – Conductive plate detail of the voltage follower CPM
5 Specific requirements for equipment categories
5.1 Specific requirements for all ionization equipment
See Annex A for information regarding theoretical background and additional information on the
standard test method for the performance of ionizers.
For the types of ionization equipment listed in 5.2, 5.3, 5.4 and 5.5, the following specific
requirements apply:
a) Decay time test – The conductive plate of the test fixture shall be charged to an initial
charging voltage, which shall be higher than the initial test voltage. The time required for
the voltage to decay from the initial test voltage to 10 % of that value shall be recorded
(refer to Clause 4 and Figure 1). Measurements shall be made with both polarities of
charging voltage.
b) Offset voltage test – The conductive plate shall be momentarily grounded to remove any
residual charges and to verify the zero setting of the voltage monitoring device. The plate
is then monitored within the ionized environment, per the procedure described for each
equipment category. The resulting observed voltage is referred to as the offset voltage.
c) Locations – The decay time and offset voltage shall be measured and recorded for each
test location and point (TP) described in the test location figures (see Table 1).
d) Same conditions – Decay time and offset voltage shall be measured under the same
conditions without any equipment adjustments.
e) Peak offset voltage – In the case of pulsed ionizers, offset voltage shall be measured and
recorded in peak values using the test equipment described in Clause 4.
f) Other parameters – Application specific parameters such as humidity, temperature, air
speed, for example shall be recorded.
IEC 61340-4-7:2025 © IEC 2025
Table 1 – Test set-ups and test locations and points (TP)
Charged plate
Offset voltage
initial voltage
Figure Number of test
Equipment category measurement time
(both polarities)
references locations
interval
V
Room ionization
Bars, grids, AC Figure 5 2 (1 to 5) min 1 000
Bars, pulsed and DC Figure 5 2 (1 to 5) min 1 000
Single polarity emitter Figure 6 3 (1 to 5) min 1 000
Two DC line Figure 7 3 (1 to 5) min 1 000
Pulsed DC emitter Figure 8 2 (1 to 5) min 1 000
Laminar flow hood
Figure 9 and
Vertical 8 (1 to 5) min 1 000
Figure 10
Figure 11 and
Horizontal 6 (1 to 5) min 1 000
Figure 12
Worksurface ionization
Benchtop Figure 13 and
12 (1 to 5) min 1 000
Figure 14
Overhead Figure 15 and
12 (1 to 5) min 1 000
Figure 16
Compressed gas ionization
Guns and nozzles Figure 17 1 10 s to 1 min 1 000
5.2 Room ionization
The area around the charged plate monitor should be cleared for a horizontal distance of 1,5 m
in all directions. The ionization system should be operated for a minimum of 30 min to stabilize
conditions in the test area.
To avoid affecting the test, the test technician should be grounded and stand outside the 1,5 m
cleared area.
Decay time from a 1 000 V initial test voltage to a 100 V final test voltage shall be measured
for both positive (+) and negative (−) polarities.
The air speed at the test location shall be recorded.
Measurements should be taken with the charged plate monitor at a distance of 1,5 m from the
ionizer under test. Since installed ionizer heights can vary, a consistent measurement height
should be selected for the evaluation of different systems. This height and the ionizer mounting
height shall be recorded in the test results.
The minimum number of test locations is determined by the type of system (see Table 1 and
refer to Figure 5 through Figure 8).
Decay time as described in 5.1 a), shall be measured at each test location.
Offset voltage as described in 5.1 b) and e) shall be determined at each test location. Offset
voltage shall be measured after a period of at least 1 min to allow the reading to stabilize (5 min
maximum).
IEC 61340-4-7:2025 © IEC 2025
NOTE 1 For AC bars or grids, the shaded areas represent areas where the coverage is less than 100 %.
NOTE 2 TP1 is directly under grid or bar while TP2 is centred between grids or bars.
NOTE 3 For AC bars and grids, a single emitter alternating between +/− polarity is used.
Figure 5 – Test locations for room ionization – AC bars, grids and DC bar systems
Three measurement locations required.
Figure 6 – Test locations for room ionization – Single polarity emitter systems
IEC 61340-4-7:2025 © IEC 2025
Three measurement locations required.
Figure 7 – Test locations for room ionization – Two DC-line systems
Two measurement locations required.
Figure 8 – Test locations for room ionization – Pulsed DC emitter systems
5.3 Laminar flow hood ionization
The test should be performed on a surface that does not contain obstructions to airflow. Unless
otherwise specified, the test surface should be static dissipative or conductive and grounded.
To avoid affecting the test, the test technician should be grounded.
Decay time from a 1 000 V initial test voltage to a 100 V final test voltage shall be measured
for both positive (+) and negative (−) polarities.
The air speed at test location TP4, as shown in Figure 9 and Figure 11, shall be recorded.
For a vertical laminar flow hood, the test set-up is shown in Figure 9 and Figure 10. Data shall
be taken at test positions TP1 through TP8 as shown in Figure 9.
For a horizontal laminar flow hood, the test set-up is shown in Figure 11 and Figure 12. Data
shall be taken at test positions TP1 through TP6 as shown in Figure 11.
IEC 61340-4-7:2025 © IEC 2025
Decay time as described in 5.1 a), shall be measured at each test location.
Offset voltage as described in 5.1 b) and e) shall be determined at each test location. Offset
voltage shall be measured after a period of at least 1 min, or as necessary to allow the reading
to stabilize (5 min maximum).
Dimensions in centimetres
Eight measurement locations required, all dimensions nominal.
Figure 9 – Test locations for vertical laminar flow hood – Top view
Dimensions in centimetres
All dimensions nominal.
Figure 10 – Test locations for vertical laminar flow hood – Side view
IEC 61340-4-7:2025 © IEC 2025
Dimensions in centimetres
Six measurement locations required, all dimensions nominal.
Figure 11 – Test locations for horizontal laminar flow hood – Top view
Dimensions in centimetres
All dimensions nominal.
Figure 12 – Test locations for horizontal laminar flow hood – Side view
5.4 Worksurface ionization
The test should be performed on a surface that does not contain obstructions to airflow. Unless
otherwise specified, the test surface should be static dissipative or conductive and properly
grounded.
To avoid affecting the test, the test technician should be properly grounded.
Decay time from a 1 000 V initial test voltage to a 100 V final test voltage shall be measured
for both positive (+) and negative (−) polarities.
IEC 61340-4-7:2025 © IEC 2025
The unit shall be measured with the heater on and off, if so equipped. The unit shall be tested
with any filters in place if so equipped. Measurements shall be made at both minimum and
maximum airflows for units with variable airflow. The air speed shall be measured and included
in the test results. End users should test ionizers with the same configuration of operating
heaters and filters that they intend to use.
For benchtop units, the ionizer shall be placed as shown in Figure 13 and Figure 14. Airflow
shall be directed at test location TP2 and measured at test locations TP2 and TP5. The charged
plate monitor shall face the ionizer. Measurements with the charged plate monitor shall be made
at test locations TP1 through TP12 as shown in Figure 13.
For overhead units, the ionizer shall be placed as shown in Figure 15 and Figure 16. Airflow
shall be measured at test locations TP5 and TP8. Measurements with the charged plate monitor
shall be made at test locations TP1 through TP12 as shown in Figure 15.
Decay time as described in 5.1 a), shall be measured at each test location.
Offset voltage as described in 5.1 b) and e) shall be determined at each test location. Offset
voltage shall be measured after a period of at least 1 min, or as necessary to allow the reading
to stabilize (5 min maximum).
Dimensions in centimetres
Twelve measurement locations required, all dimensions nominal.
Figure 13 – Test locations for benchtop ionizer – Top view
Dimensions in centimetres
All dimensions nominal.
Figure 14 – Test locations for benchtop ionizer – Side view
IEC 61340-4-7:2025 © IEC 2025
Dimensions in centimetres
Twelve measurement locations required, all dimensions nominal.
Figure 15 – Test locations for overhead ionizer – Top view
Dimensions in centimetres
All dimensions nominal.
Figure 16 – Test locations for overhead ionizer – Side view
5.5 Compressed gas ionizers – Guns and nozzles
The test should be performed on a surface that does not contain obstructions to airflow. Unless
otherwise specified, the test surface should be static dissipative or conductive and properly
grounded.
To avoid affecting the test, the test technician should be properly grounded.
Decay time from a 1 000 V initial test voltage to a 100 V final test voltage shall be measured
for both positive (+) and negative (−) polarities.
IEC 61340-4-7:2025 © IEC 2025
Unless otherwise specified, the input pressure shall be 200 kPa. End users should test
compressed gas ionizers in the same configuration of input pressure and distance that they
intend to use.
The tests shall be performed using the test set-up shown in Figure 17.
Decay time as described in 5.1 a), shall be measured at the test location.
Offset voltage as described in 5.1 b) and e) shall be determined at the test location. Offset
voltage shall be measured after a period of at least 10 s or as necessary to allow the reading
to stabilize (1 min maximum).
Dimensions in centimetres
One measurement location required, all dimensions nominal.
Figure 17 – Test locations for compressed gas ionizer (gun or nozzle) – Side view
IEC 61340-4-7:2025 © IEC 2025
Annex A
(informative)
Theoretical background and additional information on the standard test
method for the performance of ionizers
A.1 Introductory remarks
The field from static charges, located on insulators or isolated conductors, can be neutralized
by oppositely charged air ions depositing on the charged bodies.
A.2 Air ions
Air ions are molecular clusters consisting of about ten molecules (often water) around a (singly)
charged oxygen or nitrogen molecule. Normally, relatively few ions are present in the air.
Typically, the number is less than 1 000 per cm . These "natural" ions are usually formed by
radiation from radioactive materials in the air, in the ground or in building materials.
For neutralization purposes, much higher ion concentrations are needed. Although radioactivity
can also be employed in such situations, the most common ion production method is by collision
between neutral molecules and electrons accelerated in an electric field with field strengths
exceeding 3 MV/m (at atmospheric pressure). This is generally referred to as high voltage
corona ionization.
A.3 Mobility and ion current
If an ion is exposed to an electric field E, it will move with an average drift speed (v) proportional
to E, i.e.
v= kE
(A.1)
where k is the mobility of the ion.
–4 2 –1 –1
Ordinary air ions have mobilities in the range of 1 to 2 × 10 m V s (square metre per volt-
second).
If the air has a concentration n of positive ions with the mobility k, and charge e, an electric field
E will cause an electric current to flow in the direction of E with the density j.
j enkE λE
(A.2)
The constant λ (enk) is called the positive conductivity of the air (or more precisely, the polar
conductivity due to the positive ions). Negative ions will move in the opposite direction of the
field, but Formula (A.2) can still be used to calculate the current density from negative ions,
when e is taken as the numerical value of the ion charge. The current density from negative
ions will thus also be in the direction of the field.
==
IEC 61340-4-7:2025 © IEC 2025
A.4 Neutralization current
If a body completely surrounded by ionized air is given a charge q, an electric field is established
around the body and charges will flow towards it and away from it. The field will vary from point
to point, but is always proportional to the charge q. The current towards the body is carried by
the ions of polarity opposite to that of q, and is known as the neutralization current. The
neutralization current is proportional to the charge q and to the relevant opposite conductivity
of the surrounding air.
A.5 Neutralization rate
If the conductivity does not change, the relative rate of charge neutralization is constant and
the charge will decay exponentially with a time constant τ equal to the permittivity of the air e
o
divided by the conductivity λ.
τλ= e /
o
(A.3)
It should be noted that it is the conductivity, not the ion concentration itself that determines the
neutralizing ability of the air. If the particle concentration of the air is increased, by smoke for
example, the average mobility of the ions, and thus the conductivity, can decrease by a factor
of ten or more. The number of charged particles per unit volume of air, i.e. the ion concentration,
can still be more or less constant.
A.6 Ion depletion and field suppression
The conditions for fulfilling Formula (A.3) are almost never met.
It
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