CISPR TR 16-4-4:2007/AMD2:2020

CISPR TR 16-4-4 ®
Edition 2.0 2020-04
TECHNICAL
REPORT
colour
inside
INTERNATIONAL SPECIAL COMMITTEE ON RADIO INTERFERENCE

AMENDMENT 2
Specification for radio disturbance and immunity measuring apparatus and
methods –
Part 4-4: Uncertainties, statistics and limit modelling – Statistics of complaints
and a model for the calculation of limits for the protection of radio services
CISPR TR 16-4-4:2007-07/AMD2:2020-04(en)

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CISPR TR 16-4-4 ®
Edition 2.0 2020-04
TECHNICAL
REPORT
colour
inside
INTERNATIONAL SPECIAL COMMITTEE ON RADIO INTERFERENCE

AMENDMENT 2
Specification for radio disturbance and immunity measuring apparatus and

methods –
Part 4-4: Uncertainties, statistics and limit modelling – Statistics of complaints

and a model for the calculation of limits for the protection of radio services

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 33.100.10; 33.100.20 ISBN 978-2-8322-8224-3

– 2 – CISPR TR 16-4-4:2007/AMD2:2020
© IEC 2020
FOREWORD
This amendment has been prepared by CISPR subcommittee H: Limits for the protection of
radio services.
The text of this amendment is based on the following documents:
Draft TR Report on voting
CIS/H/402/DTR CIS/H/407A/RVDTR

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 amendment and the base publication will
remain unchanged until the stability date indicated on the IEC website under
"http://webstore.iec.ch" in the data related to the specific publication. At this date, the
publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct understanding
of its contents. Users should therefore print this document using a colour printer.

_____________
2 Normative references
Replace the references to IEC 60050(161) and CISPR 11 with the following:
IEC 60050-161, International Electrotechnical Vocabulary (IEV) – Part 161: Electromagnetic
compatibility (available at http://www.electropedia.org)
CISPR 11, Industrial, scientific and medical equipment – Radio-frequency disturbance
characteristics – Limits and methods of measurement
Add the following new reference:
CISPR 15:2018, Limits and methods of measurement of radio disturbance characteristics of
electrical lighting and similar equipment

© IEC 2020
3 Terms and definitions
Replace Clause 3 with the following new Clause 3:
3 Terms, definitions, symbols and abbreviated terms
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60050-161 and the
following apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1.1
complaint
request for assistance made to the RFI investigation service by the user of a radio receiving
equipment who complains that reception is degraded by radio frequency interference (RFI)
3.1.2
RFI investigation service
institution having the task of investigating reported cases of radio frequency interference and
which operates at the national basis
EXAMPLE  Radio service provider, CATV network provider, administration, regulatory authority.
3.1.3
source
any type of electric or electronic equipment, system, or (part of) installation emanating
disturbances in the radio frequency (RF) range which can cause radio frequency interference
to a certain kind of radio receiving equipment

3.2 Symbols and abbreviated terms
E permissible interference field strength at the point A in space where the antenna of
ir
the victim receiver is located – without consideration of probability factors
E permissible interference field strength at the point A in space where the antenna of
Limit
the victim receiver is located – with consideration of probability factors
protection ratio
R
P
C coupling factor describing the proportionality of the field strength E with the square
PV
root of the power P injected as common mode into the radiating structure by the
apparatus (GCPC)
Group A defined PV generator group for single-family detached houses
Group B defined PV generator group for multi-storey buildings with flat roof tops
Group C defined PV generator group for sun tracking supports (“trees”)
Group D defined PV generator group for large barns in the countryside
ρ probability of an individual PV generator being a member of Group i
i
C group-independent mean value for the coupling factor
PV
– 4 – CISPR TR 16-4-4:2007/AMD2:2020
© IEC 2020
P disturbance power emitted by a GCPC with the complex source impedance Z
S S
P power injected into the PV generator eventually radiated via that installation
L
P disturbance power determined at the DC-AN on a standardized test site according
TC
to CISPR 11 with fixed impedance Z = 150 Ω
TC
U permitted disturbance voltage limit
Limit
P probability for time coincidence (µ in dB)
7 P7
P probability for location coincidence (µ in dB)
8 P8
P probability for frequency coincidence inclusive harmonics(µ in dB)
4 P4
m mismatch loss in use case (between the GCPC with complex source impedance Z
L S
and the PV generator with complex load impedance Z )
L
m mismatch loss in test case (between the GCPC with complex source impedance Z
TC S
and the DC-AN according to CISPR 11 with measurement impedance fixed to
Z = 150 Ω)
TC
AMN artificial mains network
CM common mode
DC-AN DC artificial network
DM differential mode
GCPC grid connected power converter
S/N noise power/signal power
5.6.5.2.10.2 Estimation for the possible range of μ
P10
Add, at the end of 5.6.5.2.10.2, added by Amendment 1, the following new Subclauses 5.6.5.3
and 5.6.5.4:
5.6.5.3 Rationale for determination of CISPR limits for photovoltaic (PV) power
generating systems
For a model for the derivation of limits for photovoltaic (PV) power generating systems see
Annex C.
5.6.5.4 Rationale for determination of CISPR limits for in-house extra low voltage (ELV)
lighting installations
For a model for the estimation of radiation from in-house extra low voltage (ELV) lighting
installations see Annex D.
Add, after the existing Annex B, the following new Annex C and Annex D:

© IEC 2020
Annex C
(informative)
Model for estimation of radiation from photovoltaic (PV)
power generating systems
C.1 Overview
This annex presents a model for the estimation of radiation from photovoltaic (PV) power
generating systems in the radio frequency range. The model is based on theoretical
assumptions, measurement and simulation results as well as on a database with the statistical
values of relevant parameters together with appropriate model factors. The simulation results
were validated by measurement.
The model was developed for verification of the limits for the LV DC power port of power
converters (GCPCs) intended for assembly into PV power generating systems specified in
CISPR 11.
The subject of interest was the frequency range below 30 MHz and PV generators with a
nominal power throughput in the range up to 20 kVA. Of the two known modes of conducted
disturbances, radiation caused by conducted common mode (CM) disturbances was found to
be dominant. Therefore the model exclusively considers radiation caused by common mode RF
currents (i.e. antenna mode currents).
The structure of this annex is divided into two main parts.
Clause C.2 describes the general model approach mainly consisting of physical rationale,
formulae and procedural methods needed for the characterization of the interrelation of the
relevant influence factors.
The approach is based on the application of practical data for the various model input
parameters gained from measurement, simulation and statistics. Clause C.3 provides the
calculation of a resulting limit which serves the primary task of verification of the limits for the
LV DC power port of power converters specified in CISPR 11.
C.2 Description of the basic model
C.2.1 Overview
To provide a model suitable for an estimation of radiation from photovoltaic (PV) power
generating systems, various influence factors have to be considered.

– 6 – CISPR TR 16-4-4:2007/AMD2:2020
© IEC 2020
Figure C.1 gives a schematic overview of the determined influence parameters considered in
the model and their interrelation.

Figure C.1 – Schematic overview of the considered model influence factors
Initially, the permissible value for the disturbance field strength limit E was determined, at
Limit
a given point A in space where the antenna of the victim receiver is located, with help of the
given formula for the mathematical interrelation of relevant parameters in a remote coupling
situation (see C.2.2).
In a second step a model for the PV power generating system was introduced to determine the
RFI potential. Subsequently, typical classes of PV power generating systems were selected.
Sets of appropriate input parameters for modelling the radiation characteristics were
determined (see C.2.3). Those input parameters comprise all the mechanical and electrical data
of the solar generator used during its simulation, including electrical permittivity and
conductivity of the surrounding ground.
Based on these conventions and assumptions, the coupling between the electromagnetic field
at the victim receiver location and the PV generator was characterized by a parameter
). By means of the field strength limit E and this coupling
(introduced as coupling factor C
PV Limit
factor C the maximum permissible disturbance power P injected into the PV generator was
PV L
estimated. Thereby the basic model for the PV power generating system was completed (see
C.2.4).
In addition, the effects of power mismatch losses in test site conditions and at the place of
operation of PV power generating systems were used to refine the model (see C.2.5).

© IEC 2020
C.2.2 Conditions at the location of the antenna of the victim receiver
Considering the technical parameters for reliable transmission and reception of the radio
service or application to be protected, the permissible interference field strength E (without
ir
consideration of probability factors) at the point A in space where the antenna of the victim
receiver is located can be determined by subtracting the necessary protection ratio R from the
P
minimum wanted field strength E needed for this radio reception (see Equation (C.1), all
w
quantities expressed in logarithmic units).
EE− R (C.1)
ir w P
The permissible interference field strength is based on the measurement bandwidth of 9 kHz
for the frequency range in question used together with the limit. If the radio service evaluated
uses the same bandwidths, as in the case of broadcast radio, no change is necessary. If
however the bandwidth of the victim radio service is lower than the measurement bandwidth, a
correction shall be applied according to 5.6.6.2 (see Equation (C.2)).
b
victim
EE= +×10 log (C.2)

ir,corr ir
b
measurement
When the calculation of limits for the DC power port of a power converter (GCPC) intended for
assembly into a PV power generating system is considered, then only the radiation coupling
path to the victim radio receiver needs to be considered. The conductive coupling via the LV AC
mains lines is considered to be highly unlikely due to heavy filtering of the AC mains power port
of the GCPC.
Equation (37) of this document is the basic calculation rule to gain the permissible disturbance
field strength limit E for use with type tests on standardized test sites. The comprehensive
Limit
formula also includes the various probability factors µ and their corresponding standard
Pi
deviations σ , reflecting the likelihood of occurrence of a real disturbance in the field, as well
Pi
as the term t σ describing the predefined statistical significance of CISPR limits for type-
β i
approved appliances. Combining Equation (37), Equation (C.1) and Equation (C.2) leads to
Equation (C.3):
EEtt +µ++. µ+ σσ− ++. σ (C.3)
Limit ir,corr P1 P10 βαi P1 P10
NOTE 1 Suitable probability factors for PV power generating systems are defined depending on the context of
application (see C.3.3).
NOTE 2 This document is based on the assumption that the signal characteristics of disturbances caused by
PV systems in its worst case are continuous, leading to equivalent outputs of all CISPR detectors.
Once the field strength limit E is found, a coupling factor C comprising the coupling
Limit PV
characteristics between the electromagnetic field at the victim receiver location and the PV
power generating system can be applied to estimate the maximum permissible disturbance
power P that can be injected into a given PV generator (see C.2.4).
L
C.2.3 Characteristics of PV generators
C.2.3.1 General
In this Subclause C.2.3 a model for the PV power generating system is introduced to determine
the permissible RFI potential. Subsequently, typical classes of PV power generating systems
are selected. Sets of appropriate input parameters for modelling of their radiation characteristics
are determined.
=
=
– 8 – CISPR TR 16-4-4:2007/AMD2:2020
© IEC 2020
C.2.3.2 Characteristic parameters of a PV generator seen as radiator of
RF disturbances
In a simplified approach, a typical PV power generator can be regarded as an ideal vertical rod
antenna with capacitive top loading. The DC power string wires are treated as antenna, while
the PV panels or modules make up its capacitive loading. This approach is applicable for
common mode radiation only, but several investigations indicated this radiation to be
predominant in the considered case.
For the specified power range (i.e. up to 20 kVA) typical PV generator configurations can be
found in large numbers. On a single-family detached house some PV panels are mounted on
the inclined roof. For multiple-family houses very often a flat top roof can be found carrying
rows of PV panels on its top. A sun tracker, which is made up by a singular steel support
carrying some PV panels that always present their broad side to the sun, and fairly large
generators on barns in the countryside, are also fairly common.
As consideration of every individual PV generator configuration is not feasible, group
representatives of PV generator types are introduced (see C.2.3.3).
Subclause C.3.4 reveals the technical parameters that were assumed and used in the
simulation for calculation of the RF characteristics of the respective group of PV generators.
C.2.3.3 Grouping of PV generators
For every individual photovoltaic power generating system or installation, the individual coupling
C
property may assume a different value, but it can be expected that PV generators with
PV
i
C
about the same geometric structure and size, will show a typical property  allocated
PV
i
somewhere in a given (predictable standard deviation) range.
As PV generators occur in various different configurations in the field, it was decided to define
group representatives of PV generator types and to create a model for each group leading to
different coupling factors C (see C.3.4), describing the interrelation between the victim
PV Group i
receiver and the respective assumed group or category of PV generators.
The defined PV generator groups are:
Group A – Single-family detached houses;
Group B – Multi-storey buildings with flat roof tops;
Group C – Sun tracking supports (“trees”);
Group D – Large barns in the countryside.
Assuming the properties of all photovoltaic power generators in the world are known and that
every individual one of those can be put into one of the predefined groups which is represented
C
by its model or type (and thus has as a describing constant) it can be defined that
PV
i
Nb of PV generators in group i
ρ = (C.4)
i
Nb of PV generators in the world
ρ
where represents the probability of an individual PV generator being a member of group i,
i
C
while the respective coupling factor describes the typical RF characteristics of this group
PV
i
(see Figure C.2).
© IEC 2020
Figure C.2 – Schematic representation of probability of existence of PV generator
groups in the field
Statistical data on the population density of the PV generators in the field is given in C.3.4.3.2.
From this data, a group-independent mean value for the coupling factor C and its variance
PV
, which is valid and typical for any PV generator configuration, can be deduced (see
σ
PV
Figure C.3).
Figure C.3 – Schematic representation of mean value C and variance σ
PV CPV
The global (or mean) value C can be calculated by Equation (C.5):
PV
CC ×ρ (C.5)
PV
∑
PV i
all groups
C
This simplified value for the global coupling factor is needed to select the type-independent
PV
limit U for the LV DC power port of power converters (GCPCs) specified in CISPR 11
TC Limit
(see Clause C.3 of this document).
=
– 10 – CISPR TR 16-4-4:2007/AMD2:2020
© IEC 2020
C.2.3.4 Electrical input parameters of the PV generator
One intermediate step of the approach is the determination of the maximum permissible
disturbance power P that may be injected into the PV generator. In power matching conditions,
L
this P is identical with the permissible disturbance power P provided by the GCPC.
L S
For thorough estimation of the RFI potential, the typical power mismatch loss between the
GCPC and the DC power interface of the respective PV generator has to be taken into account
which requires knowledge of the complex impedances of GCPCs and PV generators
(see C.2.5).
C.2.4 Coupling between the electromagnetic field at the victim receiver location and
PV power generating system
C.2.4.1 General
When assessing the disturbance potential of any given apparatus with any attached structure,
the relationship between the disturbance field strength E at a given point A in space and
Limit
the RF power P fed into the radiating structure by the given apparatus has to be determined.
L
The relevant technical parameter or characteristic of a given PV generator is its frequency
dependent coupling factor C .
PV
For this task, the disturbance source, i.e. the grid connected power converter (GCPC) can be
modelled as a common mode power generator that injects a certain power P into a radiating
structure through its DC power port. The AC power port connects directly or via the PE
conductor in the AC mains cable local ground as the counterpoise of the radiating structure. A
block scheme covering this situation is shown in Figure C.4.

Figure C.4 – General model for coupling of CM disturbances of a GCPC
to an attached photovoltaic power generating system (PV generator)
In a first approach the observation point A in space is assumed to be located at a fixed distance r
from the PV generator. The electrical (disturbance) field strength E of the electromagnetic field
emanating from the radiating structure is proportional to the square root of the real power P fed
into the PV generator, due to the linearity of Maxwell's equations.
For a single point in space, a fixed function C = C (f) (coupling factor) describes the
PV PV
proportionality of the field strength E with the square root of the power P injected into the
radiating structure by the apparatus (GCPC), as given in Equation (C.6).

© IEC 2020
ECP × (C.6)
PV
For EMC considerations the situation at a fixed distance (e.g. the CISPR protection distance of
10 m or 30 m) is needed. For real objects many points in space with the property of having a
given distance to the EUT exist, for example in different azimuth directions and at different
heights. This applies to simulation and measurement equally. Therefore the field strength used
in Equation (C.6) shall undergo some kind of maximization procedure before being used for the
covers the worst case
calculation of the coupling factor. Henceforward this parameter C
PV
radiation properties/characteristics of the model for the fixed installation and is explicitly valid
for one given fixed distance r and one specific group (A, B, C or D) of PV generators. By means
of Equation (C.7) the maximum permissible disturbance power that may be injected into the PV
generator P can be calculated to:
L
E
Limit
(C.7)
P =
L
C
PV
Basically, it does not matter whether a victim receiver's antenna picks up either the electric or
the magnetic portion of the radiated disturbance and which of the two coupling mechanisms is
predominant for the respective distance. They differ, because for most frequencies the victim
receiver is in the near field zone of the radiating structure.
Using the coupling factor for the electric field strength and the magnetic field strength to
calculate the resulting field strengths appearing at the point in question, it can be seen, that the
two coupling factors can be compared to each other in the same unit (Equation (C.8)). The
disturbance field strengths, which are compared to each other and to the field strength of the
radio service, are in the far field of the transmitter.

EC ⋅ P
C
PV elec
 E PV elec
→= (C.8)

HC
HC ⋅ P PV mag

PV mag

By multiplying the coupling factor for the magnetic field C with the free space impedance
PV mag
Z
, the results can be compared in the same units. Note that the coupling factor for the
Ω m
magnetic fields will also be given in the unit (see Equation (C.9)).
 

Ω 1
CCZ ⋅
  (C.9)

PV elec PVmag
m
m⋅ Ω
  
 
NOTE Generally electric and magnetic fields are not interrelated by the free space impedance Z in the near field.
By convention, the coupling factor for the required protection distance is defined as the mean
value of all field strengths determined for a number of points in the xy-plane at the required
distance. When only four spatial directions are assessed, the final values of the coupling factor
can be calculated by
CCCCC= mean( , , , )
PV elec PV elec 0° PV elec 90°°°PV elec 180 PV elec 270
(C.10)
CCCCC= mean( , , , )
PV mag PV mag 0° PV mag 90° PV mag 180°°PV mag 270
In a last step the predominant coupling (electric or magnetic) is found by maximization.
=
=
=
=
– 12 – CISPR TR 16-4-4:2007/AMD2:2020
© IEC 2020
CCCZ max( ,× ) (C.11)
PV PV elec PV mag 0
C.2.4.2 Determination of coupling factor by simulation C
PV sim
One approach to determine the coupling factor is to carry out simulations with a Maxwell
equation solver (i.e. NEC2, FEKO, Concept).
Taking a defined representative geometrical configuration for each PV generator group as
basis, a relationship between the injected disturbance power and the resulting radiated
disturbance field strength in a point A in space at a defined distance from the PV generator can
be found.
The main input for the simulation is the geometry of the photovoltaic generator. This mechanical
structure needs to be programmed into the simulating engine. An example is shown in Figure
C.5.
Figure C.5 – Geometric representation of a PV generator with 18 modules
In the defined structure, common mode power is injected at the feed point (indicated by a purple
circle in the middle of the feed line) and the field strength is calculated in a cuboid around the
shall be calculated
structure. The distance from the structure at which the coupling factor C
PV
determines the size of the cuboid in x and y directions. The protection distance in CISPR
standards is often 3 m, 10 m or 30 m. For a large structure like a photovoltaic array, calculations
for the protection distance of 3 m are not used for the example presented in this document. The
size of the cuboid in vertical z direction shall be twice the height of the structure itself.
The output of the simulation is the field strength on the surface of the pre-programmed cuboid.
Choosing a point on the xy-plane at a distance corresponding to the required protection distance
defines a vertical line (see Figure C.6).
=
© IEC 2020
Dimensions in metres
Figure C.6 – Field strength determination by maximization (height scan) along a red line
The maximum of all field strengths in the cross-section between this line and the cuboid
represents the final field strength for the distance. Ideally this procedure would be repeated for
each angular direction, however it suffices to consider only the four different orthogonal
directions in space. The coupling factor C is then derived according to Equations (C.10)
PV sim
and (C.11).
C.2.4.3 Determination of coupling factor by measurement C
PV meas
The coupling factor introduced by Equation (C.6) can also be determined by measurement.
However, as the coupling factor is defined in transmission mode, it is difficult to measure the
field strength distribution around a typical setup for a PV generator, since the setup is too large
for accurate measurement in most available shielded rooms. On the other hand it is not possible
to actually transmit a potential test signal on any frequency at the installation site of a PV
generator, because of national restrictions. However, under specific operating conditions (e.g.
limitation of transmission to suitable single test frequencies) a measurement on real
installations is feasible.
For these measurements, the DC wires of the PV generator shall be disconnected from the
GCPC, shorted and connected to a typical antenna tuner. The tuner should be grounded the
same way an installed GCPC would be grounded. The tuner shall be able to tune the feed point
impedance of this “antenna” to the 50 Ω output of the transmitter at all test frequencies, such
that only very little RF reflection occurs. The actual forward and reflected power shall be
measured and monitored during the procedure with a power meter.
The field strength shall then be measured at a pre-defined fixed distance from the outer
boundary of the PV installation (e.g. at 10 m or 30 m). The measurement should be made in the
four dominant perpendicular directions at heights starting from 1 m above ground level up to
twice the installation height. If this cannot be achieved, the measurement can be simplified to
fewer directions and lower and fewer heights.
A comprehensive result table of this suite of measurements shall provide the following
information:
1) frequencies used for testing;

– 14 – CISPR TR 16-4-4:2007/AMD2:2020
© IEC 2020
2) location (distance r from the boundary of the PV generator, orientation in 90° angles and
height above ground);
3) forward and reflected power to determine the radiated power P (power mismatch
L
considered);
4) total electric and magnetic field-strength (derived from the x, y, and z components);
5) ambient noise level of electric and magnetic field strength;
6) determined maximum value of the field strength reading obtained in each height;
7) determined mean of the measured field strength values E and H , between for
meas meas
example the four perpendicular directions used for the measurements;
8) evaluation result: maximum of measured coupling factors C and C .
PV elec meas PV mag meas
The respective coupling factors can be calculated from the test results by means of Equations
(C.10) and (C.11).
C.2.4.4 Validation of simulation results with measurements
Comparison of measurement and simulation results will always show discrepancies. On the one
hand reasonable simulation does not seek to reproduce reality completely (input parameters
will be simplified or in some cases will not be sufficiently known), but focusses on the assumed
main influence factors. On the other hand, measurements are also influenced by unwanted
factors (uncertainty characteristics of the test equipment, environmental influences in situ,
limited height scan capabilities, access problems in different azimuth directions, etc.),
especially in the case of the complex test setup referred to in this annex.
To check and increase the accuracy of the simulation, measurements on several PV generator
structures shall be performed to verify the simulation results (see C.3.4).
C.2.5 Considerations of power mismatch losses
C.2.5.1 General
Subclause C.2.5 contains mathematical considerations regarding the usual power mismatch
conditions between the PV generator and the GCPC at the installation site of the PV generator.
In addition, the power matching conditions between the GCPC and the DC-AN in the test case
according to CISPR 11 can be considered. This allows conclusions to be drawn from ordinary
GCPC type test data about the maximum disturbance power P of the GCPC deliverable in a
S
given installed PV generator.
Due to the representation of test site conditions (Equation (C.15)) in the measurement
uncertainty and the lack of the representation of the relationship between the maximum
permissible power in the test case and in the installation case (Equation (C.16)) in any other
investigations (e.g. radiation from AC mains grid networks), this option can be added if this
scenario type is required. But then the related factors, for example measurement uncertainty or
AC mains, grid investigations and limits may have to be adjusted in a similar way.
C.2.5.2 Power mismatch conditions at the installation site of the PV power
generating system
In practice there is a certain loss of power compared to power matching conditions between
source and load, when the source of RF disturbances, in this case the PV power converter
(GCPC), is connected to an RF load, in this case the installed PV generator.
This quantity is denoted as the mismatch loss m and can be considered as a real attenuation.
L
For a GCPC with the complex source impedance Z emitting a disturbance power P into the
S S
© IEC 2020
PV generator with the complex load impedance Z , the complex reflection coefficient Γ and the
L
final loss can be calculated by Equation (C.12).
ZZ−
LS
Γ=
ZZ+
LS
m= 1−Γ (C.12)
L

M 10⋅log 1−Γ

L

The actual power P injected into the PV generator, which is mainly radiated via that installation,
L
is therefore reduced to (see Equation (C.13)):
PmP ⋅ (C.13)
L LS
If P is known, then the maximum permissible disturbance power P that can be injected by the
L S
GCPC can be calculated with Equation (C.13).
Subclause C.3.6 gives some statistical data of impedances of PV generators (Z ) and GCPCs
L
(Z ) to enable the determination of m .
S L
C.2.5.3 Power mismatch conditions at the test site
In general, P will not be known, but can be derived from a measurement of P on a
S TC
standardized test site according to CISPR 11. The measurement impedance is fixed to
Z = 150 Ω, due to the technical parameters of the DC-AN, while the power converter still has
TC
the complex source impedance Z . Measuring P in the test case (i.e. the disturbance power
S TC
determined at the DC-AN) the unknown P can be calculated by
S
PmP ⋅ (C.14)
TC TC S
with m being described by
TC
150Ω− Z
S
Γ =
TC
150Ω+ Z
S
(C.15)
m 1−Γ
TC TC
C.2.5.4 Conclusion to test conditions
The relationship between the maximum permissible power in the test case P and in the
TC
installation case P is given by the ratio of the two mismatch losses (Equation (C.16)):
L
Pm
TC TC
= (C.16)
Pm
LL
The maximum permissible disturbance power P of the power converter (GCPC) is always
S
higher than or equal to the measurement result in the test case, as both mismatch factors work
=
=
=
=
– 16 – CISPR TR 16-4-4:2007/AMD2:2020
© IEC 2020
one against the other. If the PV generator actually has an input impedance of 150 Ω, then m
TC
and m are equal and cancel out.
L
If P is known, the respective limit for the permitted disturbance voltage at the DC power port
TC
of the GCPC can be calculated using the following relation (Equation (C.17)):
UP V 150Ω× W
Limit  TC 
(C.17)

U V
Limit 
 
U dB μV 20×log
( )
TC Limit 10


1μV

C.3 Calculation based on practical values for the verification of the limits
specified in CISPR 11
C.3.1 General
Clause C.3 presents a calculation based on practical values gained by measurement, simulation
and statistical data for the introduced parameters of the model, to fulfil the primary task of the
verification of the limits for the LV DC power port of power converters intended for assembly
into PV power generating systems specified in CISPR 11.
The following list gives an overview of the parameters needed for the verification for a given
radio service or application. The following subclauses will describe in detail the assumptions
made to gain concrete values for the calculation.
• wanted signal field strength E ;
w
• required S/N respectively protection ratio R ;
P
• probability for time coincidence P ;
• probability for location coincidence P ;
• probability for frequency coincidence inclusive harmonics P ;
• global coupling factor C ;
PV
• test site correction m ;
TC
• mismatch loss at installed PV generator m .
L
Some quantities, for example t = 0,84 and t = 0,84 used in this Clause C.3 to calculate
α β
validation values in accordance with Clause C.2, are defined in the main clauses of this
document. Furthermore σ , which describes the predefined statistical significance of CISPR
i
limits for type-approved appliances, was set to zero, as the application of the 80/80-rule was
discontinued.
C.3.2 Determination of the maximum permissible interference field strength E at the
ir
location of the antenna of the victim receiver
The maximum permissible interference field strength E for the disturbance is determined by
ir
subtracting the protection ratio from the wanted signal field strength of the radio application.
Usually these parameters are given in ITU-R publications, but for simplicity CISPR has collected
and published the results in the "Radio Services Database" on the IEC website under the EMC
technology sector.
=
=
© IEC 2020
Here the radio application to be protected is chosen to calculate the permissible disturbance
field strength E by using Equation (C.1).
ir
EXAMPLE A wanted signal field strength E = 44 dB(µV/m) and a necessary signal-to-noise or protection ratio
w
R = 27 dB is taken, for good radio reception from a radio broadcast AM transmitter operating in the 31 m RF band.
P
This has to be evaluated for every entry in the radio services database resulting in a function
for E dependent on the frequency.
ir
C.3.3 Probability factors
C.3.3.1 General
The disturbance will not actually occur in all cases, due to the fact that victim and source need
to coincide in time, location and frequency. These three probability factors are assumed to play
the major role in a disturbance scenario with a PV power generating installation.
When logarithmic probability factors are calculated, the linear probability shall be converted to
a logarithm in base 10 and multiplied with a factor of 10, which originates from the signal-to-
disturbance ratio defined as ratio of received signal power to the received disturbance power.
Solely for distance ratios a factor of 20 shall be used.
C.3.3.2 Probability factor for time coincidence µ and σ
P7 P7
The disturbance can only occur at times, when the PV power generating system is in operation.
The average day time is 12 h, but the production of energy is a bit less, due to mounting of the
solar modules on an inclined plane. As an average of time 10 h are chosen, as the majority of
installations are of this kind (Equation (C.18)).
 10
µ =−10×log =3,8 dB (C.18)
 
P7 10
 
However, there are some other installation types also present, such as sun trackers or flat
mounted modules. Therefore the “in operation” interval can vary in a wide range between 4 h
and 20 h per day following an assumed uniform distribution that can be calculated by
Equation (C.19):
 20  4
10×log −×10 log
   
24 24
   
σ =−=2 dB (C.19)
P7
23×
C.3.3.3 Probability factor for location coincidence µ and σ
P8 P8
Conclusions on a representative probability factor for location coincidence were drawn based
on data from Germany using information from the statistical data used for the determination of
the coupling factor.
The value of 1,038 million photovoltaic installations registered combined with the amount of
40,96 million households (data status 2015) leads to a photovoltaic installation density of about
2,5 %. Taking into account future growth, a value of 1,6 million PV systems is taken as basis
for the calculation leading to a density of 4 %. It is assumed that every house has four
neighbours (front, rear, left and right) within the protection distance. However the total number
of installations can vary (e.g. depending on other factors such as national funding), so
photovoltaic installation densities in the field between 2 % and 8 % are assumed. Moreover, it
is assumed that there is radio broadcast reception in every household.

– 18 – CISPR TR 16-4-4:2007/AMD2:2020
© IEC 2020
These assumptions lead to Equation (C.20):
µ =−10×log 4× 0,04 =8 dB (C.20)
( )
P8 PV 10
10×log 4× 0,02 −10×log 4× 0,08
( ) ( )
10 10
σ =−=3 dB
(C.21)
P8 PV
However, there is only one amateur station in every thousand households in a world average.
Therefore an additional location coincidence shall be applied in the case of the amateur radio
service.
µ =−10×log ( 0,001)=30 dB (C.22)
P8 AmaR 10
10×log ( 0,0005)−×10 log 0,005
( )
10 10
σ =−=5 dB (C.23)
P8 AmaR
C.3.3.4 Probability factor for frequency coincidence µ and σ
P4 P4
The frequency probability can be estimated by considering typical disturbance spectra of
GCPCs.
Assuming that about 3 MHz out of the 30 MHz are occupied by emission, this leads to Equation
(C.24):
3
µ =−10×log =10 dB (C.24)

P4 10

As the characteristic spectra of GCPCs vary across a broad range, a rather high uncertainty
needs to be assigned, which leads to an assumption according to Equation (C.25):
σ = 5 dB (C.25)
P4
C.3.3.5 Maximum permissible field strength E considering probability factors
Limit
For every calculated E according to C.3.2 the probability factors are applied using
ir
Equation (C.3) and result in a frequency dependent E .
Limit
EXAMPLE 1 In the case of the shortwave radio broadcast service in the 31-m-band introduced in C.3.2, with the
wanted field strength of 44 dB(µV/m) and its protection ratio of 27 dB, taking into account the probability factors and
their distributions (C.3.3.2 to C.3.3.4) a maximum permissible field strength of 33,6 dB(µV/m) can be calculated.
2 22
E = E− R+µ+µ+µ+ t⋅ σ+σσ+
Limit W P P4 P7 P8 α P4 P7 P8
44− 27+10+ 3,8+−8 0,84⋅ 5+ 2+ 3 dB μV m 33,6dB μV m
( ) ( )
( )
EXAMPLE 2 In the case of the amateur radio service in the 20-m-band, with a sensitivity of -11 dB(µV/m) and its
protection ratio of 10 dB, taking into account the probability factors and their distributions (C.3.3.2 to C.3.3.4) a
maximum permissible field strength of 29,4 dB(µV/m) can be calculated.
= =
© IEC 2020

b
2 22
victim
E = E− R−10⋅log +µ+µ+µ+ t⋅ σ+σσ+

Limit W P 10 P4 P7 P8 α P4 P7 P8
b
measurement
 2700 
22 2
=−11−10−⋅10 log +10+ 3,8+ 38− 0,84⋅ 5++2 6 dB(μV m)=29,4dB(μV m)
 10 

 
C
C.3.4 Global coupling factor
PV
C.3.4.1 Determination of coupling factors C by simulation
PV
i sim
C.3.4.1.1 General
Subclause C.3.4.1 gives the simulation results for the predefined groups of typical PV
generators in the power range up to 20 kVA at a distance of 10 m from the outer boundary
exclusively.
The following simulations (except for Group C) have been performed with the NEC2 calculating
engine with a Sommerfeld ground model (conductivity σ = 5 mS/m and permittivity ε = 13).
r
Due to this, direct connection to ground is not feasible and a certain capacitive coupling has
been introduced using radial wires.
C.3.4.1.2 Simulation results for the coupling factor C – Group A
PV
Group A sim
(Single-family detached houses)
For this simulation the average array height of the photovoltaic generator was assumed to be 6
m and with a tilt angle of 37°. In the model, the connection of the DC wires goes directly to the
frame of the modules. Alternatively the whole PV panel structure can be simulated as a
complete wire mesh forming a tilted rectangular plane with dimensions of 6 m × 4,5 m. The
position of the PV power converter (GCPC) was assumed to be near the ground. See Fig
...