CISPR 16-2-1:2008/AMD2:2013

CISPR 16-2-1 ®
Edition 2.0 2013-03
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
INTERNATIONAL SPECIAL COMMITTEE ON RADIO INTERFERENCE
COMITÉ INTERNATIONAL SPÉCIAL DES PERTURBATIONS RADIOÉLECTRIQUES

AMENDMENT 2
AMENDEMENT 2
Specification for radio disturbance and immunity measuring apparatus and
methods –
Part 2-1: Methods of measurement of disturbances and immunity – Conducted
disturbance measurements
Spécifications des méthodes et des appareils de mesure des perturbations
radioélectriques et de l'immunité aux perturbations radioélectriques –
Partie 2-1: Méthodes de mesure des perturbations et de l'immunité – Mesures
des perturbations conduites
CISPR 16-2-1:2008/A2:2013
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CISPR 16-2-1 ®
Edition 2.0 2013-03
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
INTERNATIONAL SPECIAL COMMITTEE ON RADIO INTERFERENCE

COMITÉ INTERNATIONAL SPÉCIAL DES PERTURBATIONS RADIOÉLECTRIQUES

AMENDMENT 2
AMENDEMENT 2
Specification for radio disturbance and immunity measuring apparatus and

methods –
Part 2-1: Methods of measurement of disturbances and immunity – Conducted

disturbance measurements
Spécifications des méthodes et des appareils de mesure des perturbations

radioélectriques et de l'immunité aux perturbations radioélectriques –

Partie 2-1: Méthodes de mesure des perturbations et de l'immunité – Mesures

des perturbations conduites
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX V
ICS 33.100.10; 33.100.20 ISBN 978-2-83220-681-2

– 2 – CISPR 16-2-1 Amend.2 © IEC:2013
FOREWORD
This amendment has been prepared by subcommittee A: Radio-interference measurements
and statistical methods, of IEC technical committee CISPR: International special committee
on radio interference.
The text of this amendment is based on the following documents:
FDIS Report on voting
CISPR/A/1023/FDIS CISPR/A/1029/RVD

Full information on the voting for the approval of this amendment can be found in the report
on voting indicated in the above table.
The committee has decided that the contents of this 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• withdrawn,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.
_____________
2 Normative references
Replace the existing reference to CISPR 16-1-2 by the following new reference:
CISPR 16-1-2:2003, Specification for radio disturbance and immunity measuring apparatus
and methods – Part 1-2: Radio disturbance and immunity measuring apparatus – Ancillary
equipment – Conducted disturbances
Amendment 1:2004
Amendment 2:2006
3 Definitions
Add, after definition 3.34 added by Amendment 1, the new terms and definitions 3.35 and
3.36 as follows:
3.35
total common mode impedance
TCM impedance
impedance between the cable attached to the EUT port under test and the reference ground
plane
NOTE The complete cable is seen as one wire of the circuit and the ground plane as the other wire of the circuit.
The TCM wave is the transmission mode of electrical energy, which can lead to radiation of electrical energy if the
cable is exposed in the real application. Vice versa, this is also the dominant mode, which results from exposure of
the cable to external electromagnetic fields.

CISPR 16-2-1 Amend.2 © IEC:2013 – 3 –
3.36
asymmetric artificial network
AAN
network used to measure (or inject) asymmetric (common mode) voltages on unshielded
symmetric signal (e.g. telecommunication) lines while rejecting the symmetric (differential
mode) signal
NOTE 1 An AAN is an AN (artifical network) that provides a simulation of the asymmetric load realized by the
telecommunication network.
NOTE 2 The term “Y-network” is a synonym for AAN.
NOTE 3 The AAN can also be used for immunity testing, where the receiver measurement port becomes the
disturbance injection port.
6.4 Operating conditions of the EUT
Replace the existing title of this subclause by the following new title:
6.4 EUT arrangement and measurement conditions
6.4.1 General
Replace the existing title and text of this subclause as follows:
6.4.1 EUT arrangement
6.4.1.1 General
Where not specified in the product standard, the EUT shall be configured as described in the
following paragraphs.
The EUT shall be installed, arranged and operated in a manner consistent with typical
applications. Where the manufacturer has specified or recommended an installation practice,
such practice shall be used in the test arrangement, where possible. This arrangement shall
be typical of the normal installation practice. Interface cables, loads and devices shall be
connected to at least one of each type of interface port of the EUT, and where practical, each
cable shall be terminated in a device typical of actual usage.
Where there are multiple interface ports of the same type, additional interconnecting cables,
loads and devices may need to be added to the EUT depending upon the results of
preliminary tests. The number of additional cables or wires of the same type should be limited
to the condition where the addition of another cable or wire does not significantly affect the
emission level, i.e. varies by less than 2 dB, provided that the EUT remains compliant. The
rationale for the selection of the configuration and loading of ports shall be included in the test
report.
Interconnecting cables should be of the type and length specified in the individual equipment
requirements. If the length can be varied, the length shall be selected to produce maximum
disturbance.
If shielded or special cables are used during the tests to achieve compliance, a note shall be
included in the instruction manual advising of the need to use such cables.
Excess lengths of cables shall be bundled at the approximate centre of the cable with the
bundles 30 cm to 40 cm in length. If it is impractical to do so because of cable bulk or
stiffness, the disposition of the excess cable shall be precisely noted in the test report.
Where there are multiple interface ports all of the same type, connecting a cable to just one of
that type of port is sufficient, provided it can be shown that the additional cables would not
significantly affect the results.

– 4 – CISPR 16-2-1 Amend.2 © IEC:2013
Any set of results shall be accompanied by a complete description of the cable and equipment
orientation so that results can be repeated. If specific conditions of use are required to meet
the limits, those conditions shall be specified and documented, for example cable length,
cable type, shielding and grounding. These conditions shall be included in the instructions to
the user.
Equipment that is populated with multiple modules (such as drawers and plug-in cards) shall
be tested with a mix and number representative of that used in a typical installation. The
number of additional boards or plug-in cards of the same type should be limited to the
condition where the addition of another board or plug-in card does not significantly affect the
emission level, i.e. varies by less than 2 dB, provided that the EUT remains compliant. The
rationale used for selecting the number and type of modules should be stated in the test
report.
A system that consists of a number of separate units shall be configured to form a minimum
representative configuration. The number and mix of units included in the test configuration
shall normally be representative of that used in a typical installation. The rationale used for
selecting units should be stated in the test report.
One module of each type shall be operational in each equipment evaluated in an EUT. For an
EUT comprising a system, one of each type of equipment that can be included in the possible
system configuration shall be included in the EUT.
The results of an evaluation of EUTs having one of each type of module can be applied to
configurations having more than one of each of those modules.
NOTE It has been found that disturbances from identical modules are generally not additive in practice.
The EUT position relative to the reference ground plane shall be equivalent to that occurring
in use. Therefore, floor-standing equipment is placed on, but insulated from, a reference
ground plane, and tabletop equipment is placed on a non-conductive table.
Equipment designed for wall-mounted operation shall be tested as tabletop EUT. The
orientation of the equipment shall be consistent with normal installation practice.
Combinations of the equipment types identified above shall also be arranged in a manner
consistent with normal installation practice. Equipment designed for both tabletop and floor
standing operation shall be tested as tabletop equipment unless the usual installation is floor
standing, then that arrangement shall be used.
The ends of signal cables attached to the EUT that are not connected to another unit or
auxiliary equipment (AuxEq) shall be terminated using the correct terminating impedance
defined in the product standard. If no product standard can be applied to the particular
configuration, the termination shall be defined by the EUT manufacturer and noted in the test
report.
Cables or other connections to auxiliary equipment located outside the test site shall drape to
the floor, and then be routed to the place where they leave the test site.
Installation of AuxEq shall be in accordance with normal installation practice. Where this
means that the AuxEq is located on the test site, it shall be arranged using the same
conditions applicable for the EUT (for example, distance from the ground plane and insulation
from the ground plane if floor standing, layout of cabling).
6.4.1.2 Arrangement of tabletop equipment
Equipment intended for tabletop use shall be placed on a non-conductive table. The size of
the table will nominally be 1,5 m by 1,0 m but may ultimately be dependent on the horizontal
dimensions of EUT.
CISPR 16-2-1 Amend.2 © IEC:2013 – 5 –
Intra-unit cables shall be draped over the back of the table. If a cable hangs closer than 0,4 m
from the horizontal ground plane (or floor), the excess shall be folded at the cable centre into
a bundle no longer than 0,4 m, such that the part of the bundle closest to the horizontal
reference ground plane is at least 0,4 m above the plane.
Cables shall be positioned as for normal usage.
If the mains port input cable is less than 0,8 m long (including power supplies integrated in the
mains plug), an extension cable shall be used such that the external power supply unit is
placed on the tabletop. The extension cable shall have similar characteristics to the mains
cable (including the number of conductors and the presence of a ground connection). The
extension cable shall be treated as part of the mains cable.
In the above arrangements, the cable between the EUT and the power accessory shall be
arranged on the tabletop in the same manner as other cables connecting components of the
EUT.
6.4.1.3 Arrangement of floor-standing equipment
The EUT shall be placed on the horizontal reference ground plane, orientated for normal use,
but separated from metallic contact with the reference ground plane by up to 15 cm of
insulation.
The cables shall be insulated (by up to 15 cm) from the horizontal reference ground plane. If
the equipment requires a dedicated ground connection, then this shall be provided and

bonded to the horizontal reference ground plane.
Intra-unit cables (between units forming the EUT or between the EUT and any auxiliary
equipment) shall drape to, but remain insulated from, the horizontal reference ground plane.
Any excess cable shall either be folded at the cable centre into a bundle no longer than 0,4 m
or arranged in a serpentine fashion. If an intra-unit cable length is not long enough to drape to
the horizontal reference ground plane but drapes closer than 0,4 m, then the excess shall be
folded at the cable centre into a bundle no longer than 0,4 m. The bundle shall be positioned
such that it is either 0,4 m above the horizontal reference ground plane or at the height of the
cable entry or connection point if this is within 0,4 m of the horizontal reference ground plane.
For equipment with a vertical cable riser, the number of risers shall be typical of installation
practice. Where the riser is made of non-conductive material, a minimum spacing of at least
0,2 m shall be maintained between the closest part of the equipment and the nearest vertical
cable. Where the riser structure is conductive, the minimum spacing of 0,2 m shall be
between the closest parts of the equipment and riser structure.
6.4.1.4 Arrangement for combinations of tabletop and floor-standing equipment
Intra-unit cables between a tabletop unit and a floor-standing unit shall have the excess cable
folded into a bundle no longer than 0,4 m. The bundle shall be positioned such that it is either
0,4 m above the horizontal reference ground plane or at the height of the cable entry or
connection point if this is within 0,4 m of the horizontal reference ground plane.
Add, after the existing Subclause 6.4.6, the new subclauses:
6.4.7 Operation of multifunction equipment
Multifunction equipment that is subjected simultaneously to different clauses of a product
standard and/or different standards shall be tested with each function operated in isolation, if
this can be achieved without modifying the equipment internally. The equipment thus tested
shall be deemed to have complied with the requirements of all clauses/standards when each
function has satisfied the requirements of the relevant clause/standard.

– 6 – CISPR 16-2-1 Amend.2 © IEC:2013
For equipment that it is not practical to test with each function operated in isolation, or where
the isolation of a particular function would result in the equipment being unable to fulfil its
primary function, or where the simultaneous operation of several functions would result in
saving measurement time, the equipment shall be deemed to have complied if it meets the
provisions of the relevant clause/standard with the necessary functions operated.
6.4.8 Determination of EUT arrangement(s) that maximizes emissions
Initial testing shall identify the frequency that has the highest disturbance relative to the limit.
This identification shall be performed whilst operating the EUT in typical modes of operation
and with cable positions in a test arrangement that is representative of typical installation
practice.
The frequency of highest disturbance with respect to the limit shall be found by investigating
disturbances at a number of significant frequencies. This provides confidence that the
probable frequency of maximum disturbance has been found and that the associated cable,
EUT arrangement and mode of operation has been identified.
For initial testing, the EUT should be arranged in accordance with the product standards as
appropriate.
6.4.9 Recording of measurement results
Of those disturbances above (L – 20 dB), where L is the limit level in dB(μV) or dB(μA), the
disturbance levels and the frequencies of at least the six disturbances having the smallest
margin to the limit L shall be recorded.
In addition, the test report shall include the value of the measurement instrumentation
uncertainty corresponding to the used test setup, calculated as per the requirements of
CISPR 16-4-2.
7.3.1 General
Replace the existing Note by the following new Note:
NOTE Some standards use the terms impedance stabilization network (ISN) for ANs for emission measurements
on telecommunication ports (i.e. AANs or Y-networks).
7.3.3 Voltage probes
Replace the existing first paragraph of this subclause by the following new paragraph:
For specifications of voltage probes, see CISPR 16-1-2.
7.4.1 Arrangement of the EUT and its connection to the AN
Replace, in the fifth dashed item of the list of this subclause, the abbreviation “ISNs” by the
new abbreviation “AANs.”
CISPR 16-2-1 Amend.2 © IEC:2013 – 7 –
Figure 6 – Test configuration: table-top equipment for conducted disturbance
measurements on power mains
Replace the existing figure and notes, modified by Amendment 1, by the following:

Non-conductive table
0,1 m
Rear of EUT to be flush
with rear of table top 6
0,8 m to
ground
plane
AE
0,8 m
AMN
Current probe
Termination
0,4 m
AAN
AMN
0,1 m
Bonded to horizontal
0,4 m to vertical reference
Bonded to horizontal
ground plane
ground plane  7
ground plane
Vertical reference
IEC  500/13
ground plane
1 Interconnecting cables that hang closer than 40 cm to the ground plane shall be folded back and forth forming a
bundle 40 cm long or less, hanging approximately in the middle between the ground plane and the table. The
minimum bend radius of the cable shall not be exceeded. If the bend radius causes the bundle length to exceed
40 cm, the bend radius shall determine the bundle length.
2 I/O cables that are connected to a peripheral shall be bundled in the centre. The end of the cable may be
terminated if required using correct terminating impedance. The total length shall not exceed 1 m – if possible.
3 EUT is connected to one AMN. Measurement terminals of AMNs and AANs must be terminated with 50 Ω if not
connected to the measuring receiver. AMNs are placed directly on the horizontal ground plane 0,8 m from the
EUT and 40 cm from vertical ground plane if the vertical ground plane is the reference ground plane (see also
Figure 7 a)). Alternatively (as shown in Figure 7 b)), AMNs are placed on the vertical ground plane 0,8 m from
the EUT, if the horizontal ground plane is the reference ground plane, which is 40 cm below the EUT. To reach
the 0,8 m distance, the AMNs may have to be moved to the side. All associated equipment is connected to a
second AMN if this second AMN is capable of supplying the necessary power. In cases where a single AMN is
not capable of supplying the necessary power, several AMNs may be used to supply the associated equipment.
4 Cables of hand-operated devices, such as keyboards, mouses, etc., shall be placed as close as possible to the
host.
5 Non-EUT components being tested.
6 Rear of EUT, including peripherals, shall all be aligned and flush with rear of table-top.
7 Rear of table-top shall be at a distance of 40 cm from a vertical conducting plane that is bonded to the floor
ground plane.
Tolerances of cable lengths and distances are as practical as possible.
Figure 6 – Test configuration: table-top equipment for conducted disturbance
measurements on power mains
– 8 – CISPR 16-2-1 Amend.2 © IEC:2013
Figure 8 – Optional example test configuration for an EUT with only a power cord
attached
Replace the existing figure and notes by the following:

P
B
M
0,4 m
0,4 m
0,3 m-0,4 m
> 0,8 m
0,8 m
IEC  501/13
1 Metallic wall 2 m × 2 m
2 EUT
3 Excess power cord (e.g., 0,02 m × 0,3 m forming a meander)
4 AMN
5 Coaxial cable
6 Measuring receiver
B Reference ground connection
M Measuring receiver input
P Power to EUT
Tolerances of cable lengths and distances are as practical as possible.
Figure 8 – Optional example test configuration for an EUT with only a power cord
attached
CISPR 16-2-1 Amend.2 © IEC:2013 – 9 –
Figure 9 – Test configuration: floor-standing equipment (see 7.4.1 and 7.5.2.2)
Replace the existing figure and notes by the following:

Use typical spacing
EUT
Insulation
0,4 m
Termination
Connector height
Current probe
0,8 m
0,1 m
AE
AMN
AMN
AAN
Bonded to horizontal
reference ground plane
IEC  502/13
1 Excess cables shall be bundled in the centre or shortened to appropriate length.
2 The EUT and cables shall be insulated (up to 15 cm) from the ground plane.
3 The EUT is connected to one AMN. The AMN can be placed on top of or immediately
beneath the ground plane.
All other equipment is powered from the second AMN.
Tolerances of cable lengths and distances are as practical as possible.
Figure 9 – Test configuration: floor-standing equipment (see 7.4.1 and 7.5.2.2)

Add, after the existing Annex F added by Amendment 1, the following new Annexes G, H and
I as follows:
– 10 – CISPR 16-2-1 Amend.2 © IEC:2013
Annex G
(informative)
Guidance for measurements on telecommunications ports

G.1 Limits
The disturbance voltage (or current) limit is defined for a TCM load impedance of 150 Ω (as
seen by the EUT at the AE port during the measurement). This standardisation is necessary
in order to obtain reproducible measurement results, independent of the indeterminate TCM
impedance at the AE and the EUT.
NOTE 1 The common mode disturbances created from the wanted signal can be controlled at the design stage of
the interface technology by giving proper consideration to the factors explained in CISPR/TR 16-3.
In general, the TCM impedance seen by the EUT at the AE port is not defined unless an
AAN/CDN is used. If the AE is located outside the shielded room, the TCM impedance seen
by the EUT at the AE port can be determined by the TCM impedance of the feed-through filter
between the measurement set-up and the outside world. A Π-type filter has a low TCM
impedance, whilst a T-type filter has a high TCM impedance.
NOTE 2 CDNs are described in IEC 61000-4-6.
AAN/CDNs do not exist for all types of cables used by EUTs. Therefore it is also necessary to
define alternative test methods that do not use AAN/CDNs (i.e. “non-invasive” test methods).
Only the cable attached to the EUT port under test is shown in the figures of Annex H.
Normally, there are several other cables (or ports) present at the EUT. At least the connection
to the mains terminal is represented in most cases. The TCM impedance of these other
connections (including a possible ground connection), and the presence or absence of these
connections during the test, can influence the measurement result significantly, in particular
for small EUTs. Therefore, the TCM impedance of the non-measured connections should be
specified for the test of small EUTs. In addition to the port under test, it is sufficient to have at
least two additional ports connected to a TCM impedance of 150 Ω (normally by using an AAN
or CDN, with the RF measurement port terminated with 50 Ω load) to reduce this influence
effect to a negligible amount.
Coupling devices for unshielded balanced pairs should also simulate the typical LCL
(longitudinal conversion loss) of the lowest cabling category (worst LCL) specified for the
telecom port under test. The intent of this requirement is to account for the transformation of
the symmetrical signal into a CM (common mode) signal, which might contribute to the
radiation when the EUT is in the end-use application. Asymmetry is built-in to an AAN to yield
the specified LCL; this asymmetry may enhance or cancel the asymmetry of the EUT. To
establish the worst case emissions and optimize test repeatability, consideration should
therefore be given to repeating the testing with the LCL imbalance on each wire of a balanced
pair when using the appropriate AAN.
Because imbalance on each balanced pair may contribute to the total common mode
conducted emission, all combinations of imbalance on all balanced pairs should be
considered. For a single balanced pair, this is a relatively minor impact on test effort – i.e. the
two wires are reversed. However, for two balanced pairs, the number of LCL loading
combinations is four (i.e. test configurations). For four balanced pairs, the number of loading
combinations grows to sixteen. Such numbers will have a significant impact on test time and
test documentation. Such testing should be undertaken with care, and properly documented if
implemented.
CISPR 16-2-1 Amend.2 © IEC:2013 – 11 –
The RF measurement port of an AAN/CDN not connected to the measuring receiver shall be
terminated in a 50 Ω load.
Table G.1 summarizes the advantages and disadvantages of the methods described in
Annex H.
Table G.1 – Summary of advantages and disadvantages
of the methods described in the specific subclauses of Annex H
Subclause H.5.2 (AAN) Subclause H.5.4 (current
Subclause H.5.3 (150 Ω
probe and CVP)
load and cable shield)
– Non-invasive (except
Smallest measurement
for the removal of the
uncertainty
insulation of the
(Possible only if
shielded cable)
AAN/CDNs with
– Always applicable for
Advantages appropriate transmission Non-invasive
shielded cables
properties are available)
– Small measurement
LCL shall be known and
uncertainty for higher
shall be taken into
frequencies
account
– Increased
measurement
uncertainty for very
low frequencies
– Not applicable in all
(< 1 MHz)
cases (needs
– No isolation against
appropriate disturbances from the
– Destruction of the
AAN/CDNs) AE side (compared to
cable insulation is
H.5.2)
necessary
– Invasive (needs
appropriate cable
– Reduced isolation – Does not assess the
connections)
against disturbances interference potential
that arises from the
from the AE side
– Needs an individual
Disadvantages conversion of the
(compared to H.5.2)
AAN/CDN for each
symmetric signal into
cable type (results in
– Does not assess the
a common mode
a high number of
interference potential
signal due to the
different AAN/CDNs)
that arises from the
limited LCL of the
conversion of the
cable network to
– No isolation to
symmetric signal into
which the EUT port
symmetric signals
a common mode
from the AE is will be connected
signal due to the
provided by an AAN
limited LCL of the
cable network to
which the EUT port
will be connected
G.2 Combination of current probe and capacitive voltage probe (CVP)
The method described in H.5.4 has the advantage of being applicable in a non-invasive way
to all types of cables. However, unless the TCM impedance seen by the EUT at the AE
connection is 150 Ω, the method of H.5.4 in general will show a result which is too high, but
never too low (i.e. worst case estimation of the emission).
G.3 Basic ideas of the capacitive voltage probe
The set-up of Figure H.3 uses a capacitive voltage probe to measure the CM voltage. There
are two approaches to the construction of a capacitive voltage probe. For either approach, if a
TCM impedance of 150 Ω is present, the capacitance of the capacitive voltage probe to the
cable attached to the EUT port under test will appear as a load in parallel with the 150 Ω TCM
impedance.
– 12 – CISPR 16-2-1 Amend.2 © IEC:2013
NOTE 1 A CVP does not simulate the differential to common mode conversion that takes place in
telecommunication networks (but which an AAN does), and therefore a CVP cannot be used to measure the
converted common mode voltage. For the same reason, a combination of a CVP and a current probe cannot
replace the AAN.
The TCM impedance tolerance is ± 20 Ω over the frequency range of 0,15 MHz to 30 MHz. If
the capacitive voltage probe loading acts to reduce the 150 Ω TCM impedance at most down
to 130 Ω, the capacitance of the capacitive voltage probe to the cable attached to the EUT
port under test should be < 5 pF at 30 MHz (the worst case frequency). At 30 MHz, 5 pF is an
impedance of approximately –j1 061 Ω, which in parallel with 150 Ω yields a combined TCM
of approximately 148 Ω. Refer to Figure G.2 of CISPR 16-1-2:2003, Amendment 1 (2004) for
further background information.
The first approach to construction of a capacitive voltage probe is to have the probe be a
single device that relies on physical distance from the cable attached to the EUT port under
test to achieve the < 5 pF loading. This style of capacitive voltage probe is described in 5.2.2
of CISPR 16-1-2:2003, Amendment 1 (2004).
The second approach to construction of a CVP uses a capacitive coupling device in close
proximity to the cable attached to the EUT port under test (the device is actually in physical
contact with the insulation of the cable attached to the EUT port under test). A standard
oscilloscope-type voltage probe having an impedance > 10 MΩ, with a probe capacitance
< 5 pF, is placed in series with the capacitive coupling device. The theory is that the probe
capacitance in series with the capacitance of the capacitive coupling device will present only
the probe capacitance to the cable attached to the EUT port under test. In practice, given the
physical size of the capacitive coupling device, it is possible to have a large stray capacitance
in parallel with the probe capacitance. If this occurs, the total capacitive loading will be
greater than that of the probe itself, and the requirement to have loading < 5 pF may be
violated. If this technique is employed, the capacitive loading should be verified by
measurement, i.e. not rely only on theory.
This capacitance measurement can be made with any capacitance meter that can operate
over the 150 kHz to 30 MHz frequency range. The capacitance is measured between the
cable attached to the EUT port under test (all wires in the cable are connected together at the
connection point to the meter) and the reference ground plane. The same type of cable used
in the conducted disturbance measurement should be used for this capacitance
measurement.
NOTE 2 The uncertainty of this method is lowest if the length of cable between the EUT and AE is less than
1,25 m. Significantly longer cables are subject to standing waves, which can adversely affect voltage and current
measurements.
G.4 Combination of current limit and voltage limit
If the TCM impedance is not 150 Ω, the measurement of the voltage or the current alone is
not acceptable, because of a very high measurement uncertainty due to the undefined and
unknown TCM impedances. However, if both voltage and current are measured with limits on
current and voltage applied simultaneously, the result is a worst case estimation of the
disturbance, as explained below.
The basic circuit for which the limits are defined is shown in Figure G.1. This circuit is the
reference for which the limits expressed in terms of current and voltage are derived; any other
measurement should be compared to this basic circuit. In Figure G.1, Z is an unknown
parameter of the EUT; Z is 150 Ω in the reference measurement.
CISPR 16-2-1 Amend.2 © IEC:2013 – 13 –

EUT
Reference measurement
I
with Z = 150 Ω
Z
Z
U
U
IEC  503/13
Figure G.1 – Basic circuit for considering the limits
with a defined TCM impedance of 150 Ω
If the measurement is performed without specifying the TCM impedance seen by the EUT, the
simplified circuit is as shown in Figure G.2, where the TCM impedance Z seen by the EUT is
defined by the AE, and can have any value. Therefore, Z as well as Z are unknown
1 2
parameters of the measurement.

EUT
AE
I
Z
U Z
0 2
U
IEC  504/13
Figure G.2 – Basic circuit for the measurement with unknown TCM impedance
If the measurement is performed using the circuit of Figure G.1, the current limit and the
voltage limit are equivalent. The relation between current and voltage will always be 150 Ω,
and either can be used to determine compliance. However, this is not the case if Z is not
150 Ω (i.e. see Figure G.2).
It is important to note that compliance with the limit is not solely determined by the source
voltage U . The interference voltage measured should use a standardized Z of 150 Ω, and
0 2
depends on Z , Z and U together. For example, with the set-up from Figure G.1, the
1 2 0
voltage limit value can be reached with an EUT containing a high impedance Z and a high
source voltage U , or with a lower U combined with a lower impedance Z .
0 0 1
is not defined, it is not possible to measure
In the more general case of Figure G.2, where Z
the exact value of the interference voltage. Because Z and U are not known, it is not
1 0
possible to derive the interference voltage, even if the value of Z is known (or is measured or
calculated from I and U). For example, if an EUT with disturbance above the limit is evaluated
only by measuring the voltage in a test set-up with low Z (Z < 150 Ω) at the AE side, the
2 2
EUT might still seem to comply with the limits. In contrast, if the same EUT is measured only

– 14 – CISPR 16-2-1 Amend.2 © IEC:2013
by measuring the current in a test set-up with high Z (for example by adding ferrites),the EUT
might again seem to comply with the limits.
However, it can be shown that if the current limit and the voltage limit are applied
simultaneously, an EUT with disturbance results exceeding the limits will always be identified
by exceeding either the current limit (if Z is < 150 Ω) or the voltage limit (if Z is > 150 Ω).
2 2
If the TCM impedance of the AE (Z ) differs significantly from 150 Ω, it is possible that an EUT
which would comply with the limits if measured with Z = 150 Ω may be deemed non-
compliant. However, it will never happen that an EUT not complying with the limits is deemed
to be compliant. A measurement according to H.5.4 is therefore a worst case estimation of the
disturbance. If an EUT exceeds the limit with the H.5.4 method, it is possible the EUT would
comply with the limits if it could be measured with Z = 150 Ω.
G.5 Adjusting the TCM impedance with ferrites
In some cases (i.e. if the TCM impedance at the AE side is originally lower than 150 Ω), it is
possible to adjust the impedance by adding ferrites on the cable attached to the EUT port
under test. Subclause H.5.5 requires measurement of the TCM impedance, and adjustment of
the ferrites at each frequency to be measured, until the TCM impedance is 150 Ω ± 20 Ω.
Therefore, the method is relatively complicated and time-consuming if applied for the full
frequency spectrum. If the TCM impedance at the AE side is originally higher than 150 Ω,
there is no way to adjust the impedance to 150 Ω by adding ferrites or shifting the position of
the ferrites for frequencies below 30 MHz (other methods to adjust the TCM impedance for
specific frequencies could be used instead).
G.6 Ferrite specifications for use with methods of Annex H
Subclause H.5.3 defines a test set-up for measuring the common mode conducted
disturbance on the shield of a coaxial cable. A load impedance of 150 Ω is connected
between the coaxial shield and the reference ground plane, as shown in Figure H.2. Ferrites
are shown placed over the coaxial shield between the 150 Ω load and the AE. The following
paragraphs present methods for verifying that the ferrites are satisfying the requirements of
H.5.3.
CISPR 16-2-1 Amend.2 © IEC:2013 – 15 –

Z
EUT AE
Coaxial cable shield
Z Z Z
eutcm
ferrite aecm
150 Ω (shield to ground)
V
V
aecm
eutcm
IEC  505/13
Key
V common mode voltage generated by the EUT
eutcm
Z common mode source impedance of the EUT
eutcm
V common mode voltage generated by the AE
aecm
Z
common mode source impedance of the AE
aecm
Z impedance of the ferrites
ferrite
Z combined impedance of the 150 Ω load, Z , and Z
ferrite aecm
Figure G.3 – Impedance layout of the components used in Figure H.2
Figure G.3 shows all of the basic impedances involved in Figure H.2. The ferrites are
specified in H.5.3 to provide high impedance such that the common mode impedance towards
the right of the 150 Ω resistor shall be sufficiently large so as to not affect the measurement
(Z in Figure G.3).
The previous paragraph infers that the combined series impedance of Z and Z
ferrite aecm
should not load down the 150 Ω resistor. The general approach in the CISPR 16 series is for
tolerance of ± 20 Ω on 150 Ω common mode loads over the frequency range of 0,15 MHz to
30 MHz. Combining these two concepts, the combined series impedance of Z and Z
ferrite aecm
in parallel with the 150 Ω resistor (Z in Figure G.3) should be no lower than 130 Ω. This in
turn implies that this relationship should hold regardless of the value of Z .
aecm
In order to establish the impedance characteristics of the ferrites, only two cases need to be
considered, i.e. Z = open circuit, and Z = short circuit. If the ferrites can be selected
aecm aecm
to satisfy these requirements, any value of Z will be acceptable.
aecm
• Case 1: Z = open circuit
aecm
The combined series impedance of Z and Z is also an open circuit. An open
ferrite aecm
circuit in parallel with the 150 Ω load yields 150 Ω. Z can be of any value.
ferrite
• Case 2: Z = short circuit
aecm
The combined series impedance of Z and Z is equal to Z . The value of Z
ferrite aecm ferrite ferrite
in parallel with the 150 Ω resistor shall then be no lower than 130 Ω. In equation form:

– 16 – CISPR 16-2-1 Amend.2 © IEC:2013
150Z
ferrite
≥ 130 Ω
150 + Z
ferrite
Solving for Z yields a value of 975 Ω. This implies that the ferrites selected for this
ferrite
application shall have a minimum impedance of 975 Ω over the frequency range of
0,15 MHz to 30 MHz. For a given set of ferrites, the minimum impedance (jωL) will occur
at the minimum frequency of 0,15 MHz.
Combining the two conditions described above, it is seen that the second condition at
0,15 MHz sets the minimum requirements for the impedance of the ferrites. Any value of
impedance for the ferrites above this value would be acceptable.
In order to establish that the selected ferrites will accomplish the intended function, use of the
test set-up shown in Figure G.4 is suggested. A traditional impedance meter/analyzer can be
used to measure the impedance between point Z (I and V in Figure G.4) and the reference
ground. Another approach is to measure the individual voltage and current at point Z then
calculate the impedance. At a minimum, the impedance measurement should be made at
0,15 MHz. However, it is advisable to measure the impedance across the entire 0,15 MHz to
30 MHz range, to ensure that any stray capacitance associated with the ferrites and the
coaxial cable does not degrade the ferrite impedance. This effect is of concern because
laboratory data have shown that it is unlikely that the desired impedance can be achieved with
only a single pass of the coaxial cable through the ferrites – i.e. multiple passes through the
ferrites are necessary. This arrangement increases the chances of stray capacitance
adversely affecting the impedance of the ferrites. It has been demonstrated that in the
laboratory the desired impedance versus frequency can be achieved.

Capacitive voltage
probe
Current
probe
Ferrites
I
V
Impedance
meter
150 Ω
Reference Test
CW out
Network analyzer
IEC  506/13
Figure G.4 – Basic test set-up to measure combined impedance
of the 150 Ω and ferrites
CISPR 16-2-1 Amend.2 © IEC:2013 – 17 –
Annex H
(normative)
Specifics for conducted disturbance on telecommunication ports

H.1 General
The purpose of this annex is to d
...