IEC 61340-4-7:2010

IEC 61340-4-7 ®
Edition 1.0 2010-01
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Electrostatics –
Part 4-7: Standard test methods for specific applications – Ionization

Électrostatique –
Partie 4-7: Méthodes d'essai normalisées pour des applications spécifiques –
Ionisation
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IEC 61340-4-7 ®
Edition 1.0 2010-01
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Electrostatics –
Part 4-7: Standard test methods for specific applications – Ionization

Électrostatique –
Partie 4-7: Méthodes d'essai normalisées pour des applications spécifiques –
Ionisation
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
U
CODE PRIX
ICS 17.200.99; 29.020 ISBN 978-2-88912-463-3
– 2 – 61340-4-7  IEC:2010
CONTENTS
FOREWORD . 3
INTRODUCTION . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 7
4 Safety requirements . 8
4.1 Personnel safety . 8
4.2 Electrical . 9
4.3 Ozone . 9
4.4 Radioactive . 9
4.5 X-ray . 9
4.6 Installation . 9
5 Test equipment . 9
6 Specific requirements for equipment categories . 10
6.1 Room ionization . 11
6.2 Laminar flow hood ionization . 11
6.3 Worksurface Ionization . 12
6.4 Compressed gas ionizers – Guns and nozzles . 12
Annex A (informative) Standard test method for the performance of ionizers. 21
Annex B (normative) Method of measuring the capacitance of an isolated conductive
plate . 27
Bibliography . 30

Figure 1 – Charged plate monitor components . 13
Figure 2– Charged plate detail . 13
Figure 3 – Test locations for room ionization – AC grids and DC bar systems . 14
Figure 4 – Test locations for room ionization – Single polarity emitter systems . 14
Figure 5 – Test locations for room ionization – Dual DC line systems . 15
Figure 6 – Test locations for room ionization – Pulsed DC emitter systems . 15
Figure 7 – Test locations for vertical laminar flow hood – Top view . 16
Figure 8 – Vertical laminar flow hood – Side view . 16
Figure 9 – Test locations for horizontal laminar flow hood – Top view . 17
Figure 10 – Horizontal laminar flow hood – Side view . 17
Figure 11 – Test locations for benchtop ionizer – Top view . 18
Figure 12 – Benchtop ionizer – Side view . 18
Figure 13 – Test locations for overhead ionizer – Top view . 19
Figure 14 – Overhead ionizer – Side view . 19
Figure 15 – Test locations for compressed gas ionizer (gun or nozzle) – Side view . 20

Table 1 – Test set-ups and test locations . 10
Table B.1 – Example measurement data . 28

61340-4-7  IEC:2010 – 3 –
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
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services carried out by independent certification bodies.
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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.
International Standard IEC 61340-4-7 has been prepared by IEC technical committee 101:
Electrostatics.
The text of this standard is based on ANSI/ESD STM3.1-2006. It was submitted to the
National Committees for voting under the Fast Track Procedure.
This bilingual version (2011-04) replaces the English version.
The text of this standard is also based on the following documents:
FDIS Report on voting
101/292/FDIS 101/299/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.

– 4 – 61340-4-7  IEC:2010
The French version of this standard has not been voted upon.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts in the IEC 61340 series, under the general title Electrostatics, can be found
on the IEC website.
The committee has decided that the contents of this publication 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.
61340-4-7  IEC:2010 – 5 –
INTRODUCTION
Grounding is the primary method used to limit static charge fwhen protecting electrostatic
discharge-susceptible items in the work environment. However, grounding methods are not
effective in removing static charges from the surfaces of non-conductive (insulative) or
isolated conductive materials. Air ionization techniques may be employed to reduce these
charges as the active parameters in charge neutralization are the conductivities of the air for
each polarity. It would be appropriate to measure either the conductivities themselves or the
ion concentrations for each polarity as this would determine the ability of the ionized air to
neutralize a charge in a given location. Annex A provides information on performance of
ionizers.
In practice, these measurements are difficult to make. A more feasible 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 may 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
standard test method:
a) radioactive emission;
b) high-voltage corona from a.c. electric fields;
c) high-voltage corona from d.c. 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 part of IEC 61340.
Users of this standard 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 part of IEC 61340 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 standard test method
should be prepared to establish reasonable performance requirements for their own
application of ionizers.
Annex B has been provided in order to provide a method for measuring capacitance of the
charged plate.
– 6 – 61340-4-7  IEC:2010
ELECTROSTATICS –
Part 4-7: Standard test methods for specific applications –
Ionization
1 Scope
This part of IEC 61340 provides test methods and procedures for evaluating and selecting air
ionization equipment and systems (ionizers).
This standard establishes measurement techniques, under specified conditions, to determine
offset voltage (ion balance) and discharge (charge neutralization) time for ionizers.
This standard does not include measurements of electromagnetic interference (EMI), or uses
of ionizers in connection with ordnance, flammables, explosive items or electrically initiated
explosive devices.
As contained in this standard, the test methods and test conditions may 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
(refer to ESD SP3.3). The user will need to decide the extent of the data required for each
application.
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.
ESD ADV1.0, Glossary of terms
ESD SP3.3, Standard practice for protection of electrostatic discharge susceptible items –

Periodic verification of air ionizers
29 CFR 1910.1000, Ozone, (OSHA) Air contaminants
29 CFR 1910.95, (OSHA) Occupational noise exposure
29 CFR 1910.242 (b), (OSHA) Compressed air used for cleaning
10 CFR 20, (NRC) Standards for protection against radiation
21 CFR 1020, (FDA) Performance standards for ionizing radiation emitting products
___________
ESD Association, 7900 Turin Road, Bldg. 3, Rome, NY 13440-2069, 315-339-6937, www.esda.org
CFR (Code of Federal Regulations) U.S. Government printing office, 732 N. Capitol Street NW, Washington,
DC 20401, 866-512-1800, http://bookstore.gpo.gov

61340-4-7  IEC:2010 – 7 –
3 Terms and definitions
For the purposes of this document, the following terms and definitions, in addition to those
specified in the ESD association glossary of terms, apply.
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 and/or neutralization of a net electrostatic charge
3.4
charge induction
redistribution of charge in an isolated conductor when placed in an electric field (e.g. from a
charged body)
NOTE Momentary grounding of such a conductor would result in its gaining a net charge.
3.5
charged plate monitor
CPM
instrument used to measure the charge neutralization properties of ionization equipment
3.6
compressed gas ionizer
ionization devices that can be used to neutralize charged surfaces and/or remove surface
particles with pressurized gas
NOTE This type of ionizer may be used to ionize the gas within production equipment.
3.7
corona
production of positive and negative ions by a very localized high electric field
NOTE The field is normally established by applying a high voltage to a conductor in the shape of a sharp point or
wire.
3.8
decay rate
decrease of charge or voltage per unit time
3.9
discharge time
time necessary for a voltage (due to an electrostatic charge) to decay from an initial value to
some arbitrarily chosen final value
3.10
emitter
conducting sharp object, usually a needle or wire, which will cause a corona discharge when
kept at a high potential
– 8 – 61340-4-7  IEC:2010
3.11
horizontal laminar flow
non-turbulent airflow in a horizontal direction
3.12
ion balance
(see offset voltage)
3.13
ionizer
device that is designed to generate positive and/or negative air ions
3.14
isolated conductor
non-grounded conductor
3.15
laminar flow hood ionization
these devices or systems provide local area ionization coverage in vertical or horizontal
laminar flow hoods or benches
3.16
offset voltage
observed voltage on the isolated conductive plate of a charged plate monitor (CPM) that has
been placed in an ionized environment
3.17
peak offset voltage
for pulsed ionizers, the maximum value of the offset voltage for each polarity, as the ionizer
cycles between positive and negative ion outputs
3.18
room ionization
ionization systems that provide large area coverage with air ions
3.19
worksurface ionization (formerly tabletop ionization)
ionization devices or systems used to control static charges at a workstation
NOTE This type includes benchtop ionizers, overhead worksurface ionizers and laminar flow hood ionizers.
3.20
vertical laminar flow
non-turbulent airflow in a vertical direction
4 Safety requirements
In addition to the safety issues mentioned in this clause, there may be local, state, national
and international safety standards or regulations that affect the operation of ionizers. Users of
this standard test method should determine if such requirements will apply to their installation
of ionizers.
4.1 Personnel safety
4.1.1 The procedures and equipment described in this part of IEC 61340 may expose
personnel to hazardous electrical conditions. Users of this standard, therefore, are
responsible for selecting equipment that complies with applicable laws, regulatory codes and

61340-4-7  IEC:2010 – 9 –
both external and internal policy. Users are also cautioned that this standard cannot replace
or supersede any requirements for personnel safety.
Ground fault circuit interrupters (GFCI) and other safety protection should be considered
wherever personnel may come into contact with electrical sources.
Electrical hazard reduction practices should be exercised and proper grounding instructions
for the equipment must be followed.
4.2 Electrical
In the case of high-voltage ionizers with exposed emitters, the corona points or wires should
be peak current limited to applicable safety requirements for the installation.
4.3 Ozone
The OSHA limit, as defined by 29 CFR 1910.1000, shall not be exceeded. If ozone-sensitive
components are in the vicinity of an ionizer, the manufacturer should provide information
and/or evaluation suggestions for the situation.
4.4 Radioactive
The manufacturer is required to obtain a license from the Nuclear Regulatory Commission
(NRC) or the NRC agreement state in which the equipment is manufactured. The
manufacturer and user shall meet all requirements of 10 CFR 20 and any other applicable
government regulations.
4.5 X-ray
The manufacturer and user shall meet all requirements of 21 CFR 1020 and any other
applicable government regulations. Typically, state and local government agencies will require
the device to be registered at its use location. X-ray devices should be installed in such a way
that prevents accidental exposure to personnel. Typically this will include some type of
enclosure for the X-ray device and electrical interlocking to turn the X-ray device off when the
enclosure is opened.
4.6 Installation
Installation should conform to applicable electrical, mechanical and safety codes, as well as
individual facility standards. Some equipment, such as compressed gas guns and nozzles
may have to meet other requirements such as 29 CFR 1910.95 for noise exposure and
29 CFR 1910.242 for personnel safety with compressed gas devices. Installation techniques
should also be applicable to the particular environment in which the ionizer is to be installed
(e.g., cleanrooms).
5 Test equipment
5.1 The instrument recommended in this standard to make performance measurements on
air ionization equipment is the CPM (refer to Figure 1). The conductive plate shall be 15 cm
by 15 cm (6“ by 6“) with a minimum capacitance of 15 pF when mounted in the test fixture
without electrical hook-ups. The total capacitance of the test circuit, with plate, shall be
20 pF ± 2 pF (refer to Annex B). The instrument recommended by this standard test method
may also be used for the periodic verification of air ionizers (refer to ESD SP3.3).
5.2 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 2 (refer to Annex B).
– 10 – 61340-4-7  IEC:2010
5.3 The isolated conductive plate, when charged to the desired test voltage, shall not
discharge more than 10 % of the test voltage within 5 min, in the absence of ionization.
5.4 The voltage on the plate shall be monitored in such a way that the system conforms to
5.1, 5.2 and 5.3. The response time of the monitoring device shall be sufficient to accurately
measure changing plate voltages.
5.5 The voltage source used to charge the plate should be current limited so as to meet
the requirements of 4.1.
6 Specific requirements for equipment categories
For the types of ionization equipment listed in 6.1, 6.2, 6.3 and 6.4, the following specific
requirements apply:
a) Discharge time test – The conductive plate of the test fixture shall be charged to an initial
test voltage and allowed to discharge to 10 % of the initial test voltage. The time required
shall be monitored and recorded for both polarities of initial charge. This time is referred to
as the discharge time (refer to 5.1 and Figure 1).
b) Offset voltage test – The conductive plate shall be momentarily grounded to remove any
residual charges and to verify zero of the 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 discharge time and offset voltage should be measured for each test
location described in the test location figures (see Table 1).
d) Same conditions – Discharge time and offset voltage shall be measured under the same
conditions without any equipment adjustments. If ionizers from different categories are to
be compared, the same test voltages shall be used for all tests.
e) Peak offset voltage – In the case of pulsed ionizers, offset voltage should be measured
and reported in peak values using the test equipment described in 5.1.
f) Other parameters – Application specific parameters such as humidity, temperature, air
velocity, etc., should be recorded.
Table 1 – Test set-ups and test locations
Offset voltage
Equipment Figure Number of test Charged plate
measurement
category references locations initial voltage
time interval
Room ionization
Grids, AC 3 2 (1 to 5) min 1 000
Bars, pulsed and DC 3 2 (1 to 5) min 1 000
Single polarity emitter 4 3 (1 to 5) min 1 000
Dual DC Line 5 3 (1 to 5) min 1 000
Pulsed DC emitter 6 2 (1 to 5) min 1 000
Laminar flow hood
Vertical 7 and 8 8 (1 to 5) min 1 000
Horizontal 9 and 10 6 (1 to 5) min 1 000
Worksurface ionization
Benchtop 11 and 12 12 (1 to 5) min 1 000
Overhead 13 and 14 12 (1 to 5) min 1 000
Compressed gas ionization
Guns and nozzles 15 1 10 s to 1 min 1 000

61340-4-7  IEC:2010 – 11 –
6.1 Room ionization
6.1.1 The area around the charged plate monitor should be cleared for a horizontal distance
of 60“ in all directions. The ionization system should be operated for a minimum of 30 min to
stabilize conditions in the test area.
6.1.2 During the test, the test technician should be grounded and stand outside the 60“
cleared area.
6.1.3 Discharge time from a 1 000 V initial voltage to a 100 V final voltage shall be
measured for both positive (+) and negative (-) polarities.
6.1.4 The air velocity at the test location should be recorded.
6.1.5 Measurements should be taken with the charged plate monitor at a distance of 60“
from the ionizer under test. Since installed ionizer heights may 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.
6.1.6 The minimum number of test locations is determined by the type of system. (See
Table 1 and refer to Figures 3 through 6.)
6.1.7 Discharge time as described in Clause 6, point a), should be measured at each test
location.
6.1.8 Offset voltage as described in Clause 6, points b) and e) should be determined at
each test location. Offset voltage shall be measured after a period of at least 1 mkin to allow
the reading to stabilize (5 min maximum).
6.2 Laminar flow hood ionization
6.2.1 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.
6.2.2 The test technician should be properly grounded.
6.2.3 Discharge time from a 1 000 V initial voltage to a 100 V final voltage shall be
measured for both positive (+) and negative (-) polarities.
6.2.4 The air velocity at test location TP4, as shown in Figures 7 or 9, should be recorded.
6.2.5 For a vertical laminar flow hood, the test set-up is shown in Figures 7 and 8. Data
should be taken at test positions TP1 through TP8 as shown in Figure 7.
6.2.6 For a horizontal laminar flow hood, the test set-up is shown in Figures 9 and 10. Data
should be taken at test positions TP1 through TP6 as shown in Figure 9.
6.2.7 Discharge time as described in Clause 6, point a), should be measured at each test
location.
6.2.8 Offset voltage as described in Clause 6, points b) and e) should 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).

– 12 – 61340-4-7  IEC:2010
6.3 Worksurface Ionization
6.3.1 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.
6.3.2 The test technician should be properly grounded.
6.3.3 Discharge time from a 1 000 V initial voltage to a 100 V final voltage shall be
measured for both positive (+) and negative (-) polarities.
6.3.4 The unit should be measured with the heater off, if so equipped. The unit should be
tested with any filters in place if so equipped. Measurements should be made at both
minimum and maximum airflows for units with variable airflow. The air velocity should 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.
6.3.5 For benchtop units, the ionizer should be placed as shown in Figures 11 and 12.
Airflow should 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 should be made at test locations TP1 through TP12 as shown in Figure 11.
6.3.6 For overhead units, the ionizer should be placed as shown in Figures 13 and 14.
Airflow should be measured at test locations TP5 and TP8. Measurements with the charged
plate monitor should be made at test locations TP1 through TP12 as shown in Figure 13.
6.3.7 Discharge time as described in Clause 6, point a), should be measured at each test
location.
6.3.8 Offset voltage as described in Clause 6, points b) and e) should 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).
6.4 Compressed gas ionizers – Guns and nozzles
6.4.1 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.
6.4.2 The test technician should be properly grounded.
6.4.3 Discharge time from a 1 000 V initial voltage to a 100 V final voltage shall be
measured for both positive (+) and negative (-) polarities.
6.4.4 Unless otherwise specified, the input pressure should be 30 psig (pounds per square
inch gauge). End users should test compressed gas ionizers in the same configuration of
input pressure and distance that they intend to use.
6.4.5 The tests should be performed using the test set-up shown in Figure 15.
6.4.6 Discharge time as described in Clause 6, point a), should be measured at the test
location.
6.4.7 Offset voltage as described in Clause 6, points b) and e) should 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).

61340-4-7  IEC:2010 – 13 –
Probe
See NOTE
Switch
Conductive plate
Insulator
Grounded surface
Ground
High voltage
power supply-
current limited
Noncontacting
voltmeter or
electrometer
Discharge timer
IEC  2591/09
NOTE See Figure 2.
Figure 1 – Charged plate monitor (CPM) components

15 cm × 15 cm (6″ × 6″)
Conductive plate
Dimension A
Insulator
Grounded surface
Ground
IEC  2592/09
NOTE Grounded surface should be ≥ 15 cm (6“) square.
Figure 2 – Charged plate detail

– 14 – 61340-4-7  IEC:2010
(or)
Charged plate
DC bars AC grids
TP1
TP2
IEC  2593/09
NOTE 1 Example for AC grids (less than 100 % coverage) and pulsed or steady-state DC bars.
NOTE 2 TP1 is directly under grid or bar while TP2 is centered between grids or bars.
Figure 3 – Test locations for room ionization – AC grids and DC bar systems

Charged plate
Emitter
E
E
TP1
TP3
E
E
TP2
IEC  2594/09
NOTE Three measurement locations required.
Figure 4 – Test locations for room ionization – Single polarity emitter systems

61340-4-7  IEC:2010 – 15 –
Charged plate
Emitter
E E E
TP1 TP2
TP3
E E E
IEC  2595/09
NOTE Three measurement locations required.
Figure 5 – Test locations for room ionization – Dual DC line systems

Charged plate Emitter
E E
TP1
TP2
E
IEC  2596/09
NOTE Two measurement locations required.
Figure 6 – Test locations for room ionization – Pulsed DC emitter systems

– 16 – 61340-4-7  IEC:2010
15 cm 15 cm
(6″) (6″)
15 cm
Rear
(6″)
TP6 TP7
TP3
TP4 TP5
Center line
of test points
Charged plate
TP1
TP8
TP2
Front edge
Center line
of test points
IEC  2597/09
NOTE Eight measurement locations required.
Figure 7 – Test locations for vertical laminar flow hood – Top view

HEPA filter
Ionizing grid
(or)
Ionizing bar
Air flow
60 cm
(24″)
Charged plate
15 cm
(6″)
IEC  2598/09
Figure 8 – Vertical laminar flow hood – Side view

61340-4-7  IEC:2010 – 17 –
15 cm 15 cm
(6″) (6″)
Rear
HEPA filter
Ionizing bar or grid
Air flow
38 cm
(15″)
TP3 TP4 TP5
Charged plate
TP1 TP6 TP2
Front edge
Center line
of test points
IEC  2599/09
NOTE Six measurement locations required.
Figure 9 – Test locations for horizontal laminar flow hood – Top view

38 cm
(15″)
HEPA filter
Charged plate
Ionizing grid
(or)
Air flow
Ionizing bar
15 cm
(6″)
IEC  2600/09
Figure 10 – Horizontal laminar flow hood – Side view

– 18 – 61340-4-7  IEC:2010
30 cm 30 cm 30 cm 30 cm
(12″) (12″) (12″) (12″)
TP1 TP4 TP7 TP10
30 cm
(12″)
Bench top
ionizer
TP2 TP5 TP8 TP11
Air flow
30 cm
(12″)
TP3 TP6 TP9 TP12
Charged plate
IEC  2601/09
NOTE Twelve measurement locations required.
Figure 11 – Test locations for benchtop ionizer – Top view
Charged plate
Bench top
ionizer
Air flow
15 cm
(6″)
IEC  2602/09
Figure 12 – Benchtop ionizer – Side view

61340-4-7  IEC:2010 – 19 –
Overhead ionizer centered
above test area
40 cm 40 cm 40 cm
(16″) (16″) (16″)
TP1 TP4 TP7 TP10
30 cm
(12″)
TP2
TP5 TP8 TP11
30 cm
(12″)
TP3 TP6
TP9 TP12
Charged plate
IEC  2603/09
NOTE Twelve measurement locations required.
Figure 13 – Test locations for overhead ionizer – Top view

Center line
of test points
60 cm
(24″)
Overhead ionizer
Air flow
45 cm
(18″)
Charged plate
15 cm
(6″)
IEC  2604/09
Figure 14 – Overhead ionizer – Side view

– 20 – 61340-4-7  IEC:2010
15 cm
(6″)
Compressed gas ionizer
Charged plate
(gun or nozzle)
Gas flow
15 cm
(6″)
IEC  2605/09
NOTE One measurement location required.
Figure 15 – Test locations for compressed gas ionizer (gun or nozzle) – Side view

61340-4-7  IEC:2010 – 21 –
Annex A
(informative)
Standard test method for the performance of ionizers

The field from static charges, located on insulators or isolated conductors, may be neutralized
by oppositely charged air ions depositing on the charged bodies.
A.1 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 may 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.2 Mobility and ion current
If an ion is exposed to an electric field E, it will move with an average drift velocity (v)
proportional to E, i.e.
v = kE (A.1)
where k = the mobility of the ion.
–4 2 –1 –1 2
Ordinary air ions have mobilities in the range of 1 to 2 × 10 m V s (meter 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 = λ E (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 Equation (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.
A.3 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 toward 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.

– 22 – 61340-4-7  IEC:2010
A.4 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.
τ = e /λ (A.3)
o
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, may decrease by a
factor of ten or more. The number of charged particles per unit volume of air, i.e. the ion
concentration, may still be more or less constant.
A.5 Ion depletion and field suppression
The conditions for fulfilling Equation (A.3) are almost never met.
It was assumed that the conductivity was not affected by the neutralization process. In the
case of room ionization, for example, the field from the charge to be neutralized may partially
deplete the air of ions. This lowers the air conductivity, making the neutralization slower than
predicted by Equation (A.3). The degree of ion depletion will increase with the field strength
from the charged body. The rate of neutralization will thus decrease as the amount of charge
to be neutralized increases.
When fans or compressed gas ionizers are used, this effect is much less pronounced.
Neutralization becomes dependent mostly on the flow rate of the ionized air.
It was also assumed that the charged body was completely surrounded by ionized air. The
field from any part of the body would contribute, according to Equation (A.2), to the
neutralization current. This is rarely the case.
Part of the electric flux from the charge will extend through any insulating supports and thus
not cause any flow of neutralizing charges to the body. This effect is called field suppression.
But even if the immediate neighborhood of the body is conducting, nearby materials,
conducting or insulating, may physically prevent ions from other regions replacing those
depositing on the charge body, again creating ion depletion.
In practice, it will not be possible to make corrections for all the deviations from the simple
case when calculating the time constant τ. Normally it will be necessary to determine the
neutralizing properties of an ionizer experimentally as explained in this standard.
A.6 Charged plate monitor and charge neutralization
A CPM is a device used to measure the neutralizing properties of an ionizer or ionizing
installation. The CPM co
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