IEC TR 61547-1:2015

Equipment for general lighting purposes - EMC immunity requirements - Part 1: An objective voltage fluctuation immunity test method

IEC TR 61547-1:2015(E) establishes an objective method and procedure for testing the immunity performance of lighting equipment against voltage fluctuation disturbances on the a.c. power port. The object of this Technical Report is to establish a common and objective reference for evaluating the immunity of lighting equipment in terms of illuminance flicker when subjected to mains voltage fluctuations. Temporal changes in the colour of the light (chromatic flicker) are not considered in this test.

General Information

• Status: Published
• Publication Date: 28-Apr-2015
• ICS: 29.140.20 - Incandescent lamps
• Technical Committee: TC 34 - Lighting
• Current Stage: DELPUB - Deleted Publication
• Start Date: 19-Oct-2017
• Completion Date: 31-Mar-2017

Relations

• Revised: IEC TR 61547-1:2017 - Equipment for general lighting purposes - EMC immunity requirements - Part 1: An objective light flickermeter and voltage fluctuation immunity test method
• Effective Date: 05-Sep-2023

Overview

IEC TR 61547-1:2015 - Equipment for general lighting purposes - EMC immunity requirements - Part 1: An objective voltage fluctuation immunity test method - is a Technical Report from the IEC that establishes an objective test method to assess how lighting equipment responds to mains voltage fluctuation disturbances. The report focuses on measuring illuminance flicker (perceived changes in light level) produced by AC supply fluctuations at the a.c. power port. Chromatic flicker (temporal changes in light colour) is explicitly excluded from this test method.

Key topics and technical requirements

• Scope and objective: Provides a common, objective reference for evaluating immunity of lighting equipment in terms of illuminance flicker under mains voltage fluctuations.
• Disturbance signal definition: Defines the mains test signal and modulation schemes used to simulate voltage fluctuations applied to the equipment under test (EUT).
• Test setup and equipment:
  • Requirements for the a.c. test voltage and mains signal parameters.
  • Optical test environment and positioning of the EUT.
  • Light sensor and amplifier specifications and signal acquisition chain (anti-aliasing filter, sampling frequency, resolution).
• Measurement and signal processing: Guidance on signal conditioning, sampling, and analysis to quantify illuminance fluctuations.
• Verification and calibration: Procedures for verifying light flickermeter performance and mains parameters before testing.
• Evaluation and reporting: Criteria for test evaluation, uncertainty considerations, and required test-report contents.
• Informative annexes: Specification and verification of a light flickermeter, uncertainty budgets, and example test results.

Practical applications and users

Who benefits from applying IEC TR 61547-1:2015:

• Lighting manufacturers validating product immunity to mains voltage fluctuations.
• EMC test laboratories developing reproducible flicker-immunity test programs.
• Product compliance and certification teams documenting illuminance flicker performance.
• Standards and test engineers harmonizing test methods across LED, fluorescent, and other lighting technologies.
• Utilities and building specifiers assessing potential flicker impact in installations.

Practical value:

• Enables objective comparison of different lighting technologies’ susceptibility to voltage fluctuations.
• Supports robust test setups (sensor selection, sampling and processing) to produce repeatable, defensible results.
• Helps manufacturers mitigate flicker-related complaints and improve product design.

Related standards

• IEC 61000-4-15 (flickermeter - referenced for voltage-based flicker measurement concepts)
• IEC 61000-3-3 (limits for voltage fluctuations and flicker, discussed in the report’s introduction)
• Other parts of the IEC 61547 series covering EMC immunity for lighting equipment

Keywords: IEC TR 61547-1:2015, voltage fluctuation immunity, lighting equipment, illuminance flicker, EMC immunity test method, light flickermeter, mains voltage fluctuations.

Standards Content (Sample)

IEC TR 61547-1 ®
Edition 1.0 2015-04
TECHNICAL
REPORT
colour
inside
Equipment for general lighting purposes – EMC immunity requirements –
Part 1: An objective voltage fluctuation immunity test method

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IEC TR 61547-1 ®
Edition 1.0 2015-04
TECHNICAL
REPORT
colour
inside
Equipment for general lighting purposes – EMC immunity requirements –

Part 1: An objective voltage fluctuation immunity test method

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.140.20 ISBN 978-2-8322-2649-0

– 2 – IEC TR 61547-1:2015 © IEC 2015
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
2 Normative references . 7
3 Terms, definitions, abbreviations and symbols . 7
3.1 Terms and definitions . 7
3.2 Abbreviations . 9
3.3 Symbols . 9
4 General . 10
5 Voltage fluctuation disturbance signal . 10
5.1 General . 10
5.2 Mains signal parameters . 12
5.3 Disturbance signal parameters and test levels . 13
6 Test setup and equipment . 14
6.1 General . 14
6.2 Test voltage . 14
6.3 Optical test environment . 15
6.4 Light sensor and amplifier . 15
6.5 Signals to be measured . 15
6.6 Signal processing . 16
6.6.1 Anti-aliasing filter . 16
6.6.2 Sampling frequency . 16
6.6.3 Signal resolution . 18
7 Verification procedure . 18
7.1 General . 18
7.2 Light flickermeter . 18
7.3 Mains voltage parameters without modulation . 18
7.3.1 Nominal voltage level . 18
7.3.2 Mains frequency . 19
7.4 Voltage fluctuation level . 19
7.4.1 General . 19
7.4.2 Option 1: measure the actual modulation frequencies and voltage levels . 19
7.4.3 Option 2: measure P -values using a flickermeter . 19
st
7.5 Light sensor and amplifier . 19
7.6 Test environment . 20
7.7 Light flicker noise . 20
8 Test procedure . 20
9 Conditions during testing . 20
10 Evaluation of the test result . 21
11 Test report . 21
Annex A (informative) Specification of the light flickermeter . 23
A.1 The voltage flickermeter . 23
A.2 Specification of the light flickermeter . 24
A.2.1 General . 24
A.2.2 Block a: illuminance adapter . 24

A.2.3 Block b: weighting filters . 24
A.2.4 Block c: squaring multiplier, sliding mean filter and scaling . 25
A.2.5 Block d: statistical analysis . 25
A.3 Verification of the light flickermeter . 26
Annex B (informative) Uncertainty considerations . 27
B.1 General . 27
B.2 General symbols . 27
B.3 Measurand . 27
B.4 Influence quantities . 27
B.5 Uncertainty budget . 29
B.6 Reference document . 29
Annex C (informative) Examples of a test result . 31
C.1 EUTs . 31
C.2 Recorded signals . 31
C.3 Results . 34
Bibliography . 36

Figure 1 – The full EMC approach for mains voltage fluctuations . 11
Figure 2 – Definition of the mains test signal including a rectangular modulated
voltage fluctuation (see Equation (1)) . 12
Figure 3 – Block diagram voltage-fluctuation immunity test . 14
Figure 4 – Example of a recorded mains voltage fluctuation and illuminance signal of a
60 W incandescent lamp . 17
Figure A.1 –Structure of the IEC 61000-4-15 flickermeter which uses voltage as input . 23
Figure A.2 – Structure of the light flickermeter . 23
Figure C.1 – EUT1: recorded signals (no mains voltage modulation) . 32
Figure C.2 – EUT1: recorded signals (with modulation) . 33
Figure C.3 – EUT2: relative illuminance: mains voltage modulation d = 0,407 % at
13,5 Hz (P = 1) . 34
st
Figure C.4 – EUT3: relative illuminance: mains voltage modulation d = 0,407 % at
13,5 Hz (P = 1) . 34
st
Figure C.5 – Graphical P results for three EUTs with rectangular modulation at five
st
frequencies (P = 1) . 35
st
Table 1 – Voltage fluctuations – Test specification of voltage fluctuations applied at
input a.c. power ports 230 V; 50 Hz . 13
Table A.1 – Test specification of illuminance fluctuations for lightmeter classifier . 26
Table B.1 – P influence quantities and their recommended tolerances. 28
st
Table B.2 – Uncertainty budget of the voltage fluctuation immunity test . 30
Table C.1 – Numerical results P calculations for three EUTs with and without
st
modulation . 35

– 4 – IEC TR 61547-1:2015 © IEC 2015
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
EQUIPMENT FOR GENERAL LIGHTING PURPOSES –
EMC IMMUNITY REQUIREMENTS –
Part 1: An objective voltage fluctuation immunity test method

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
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patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
The main task of IEC technical committees is to prepare International Standards. However, a
technical committee may propose the publication of a technical report when it has collected
data of a different kind from that which is normally published as an International Standard, for
example "state of the art".
IEC TR 61547-1, which is a technical report, has been prepared by subcommittee 34: Lamps
and related equipment.
The text of this technical report is based on the following documents:
Enquiry draft Report on voting
34/212/DTR 34/220A/RVC
Full information on the voting for the approval of this technical report can be found in the
report on voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts in the IEC 61547 series, published under the general title Equipment for
general lighting purposes – EMC immunity requirements, 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 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.
A bilingual version of this publication may be issued at a later date.

IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct
understanding of its contents. Users should therefore print this document using a
colour printer.
– 6 – IEC TR 61547-1:2015 © IEC 2015
INTRODUCTION
Flicker perception, and the associated IEC 61000-3-3 standard for voltage fluctuations and
the flickermeter IEC 61000-4-15, is based on the 60 W incandescent lamp. As a result of the
phasing out of incandescent lamps and the widespread introduction of alternative lighting
equipment technologies, a new reference lamp was considered. It has been demonstrated
that new lighting technologies are in general less but sometimes also more sensitive to supply
voltage fluctuations than the current 60 W incandescent lamp. CIGRE working group C4.111
has assessed the impact of new lighting technologies on the existing flicker standards. Most
likely, the present flicker sensitivity curve of IEC 61000-3-3 will stay as the reference, but
because of the increased diversity of sensitivity of lighting equipment to voltage fluctuations,
there is a future need for a voltage-fluctuation immunity test specifically for lighting
equipment. In this way, the full-EMC approach (Figure 1) is introduced for flicker, i.e. limit
voltage fluctuations caused by equipment connected to the grid, and in addition establish a
minimum level of flicker immunity of lighting equipment against these voltage fluctuations.
This technical report provides an objective method and procedure for testing the immunity of
lighting equipment against mains voltage fluctuations. With this technical report, the lighting
industry can gain experience with the flicker immunity test. Results of actual tests will be
reported separately in IEC TR 61547-2.
Based on the experience with this immunity test method, the adoption of a similar test in the
immunity standard for lighting equipment IEC 61547 will be considered.

EQUIPMENT FOR GENERAL LIGHTING PURPOSES –
EMC IMMUNITY REQUIREMENTS –
Part 1: An objective voltage fluctuation immunity test method

1 Scope
This Part of 61547, which is a Technical Report, establishes an objective method and
procedure for testing the immunity performance of lighting equipment against voltage
fluctuation disturbances on the a.c. power port.
The object of this Technical Report is to establish a common and objective reference for
evaluating the immunity of lighting equipment in terms of illuminance flicker when subjected to
mains voltage fluctuations. Temporal changes in the colour of the light (chromatic flicker) are
not considered in this test.
This method and procedure can be applied to lighting equipment which is within the scope of
IEC technical committee 34, such as lamps and luminaires, intended for connection to a low
voltage electricity supply. Independent auxiliaries such as drivers can be tested also by
application of a representative light source to that auxiliary.
The method and procedure described in this technical report are based on the IEC 61000-3-3
standard for voltage fluctuation limits and the flickermeter standard IEC 61000-4-15.
The test method described in this report applies to lighting equipment rated for 230 V a.c. and
50 Hz (for verification purposes).
NOTE The principle of the method can be applied for other nominal voltage and frequency ratings.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and
are indispensable for its application. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 61000-3-3:2013, Electromagnetic compatibility (EMC) – Part 3-3: Limits – Limitation of
voltage changes, voltage fluctuations and flicker in public low-voltage supply systems, for
equipment with rated current ≤ 16 A per phase and not subject to conditional connection
IEC 61000-4-15:2010, Electromagnetic compatibility (EMC) – Part 4-15: Testing and
measurement techniques – Flickermeter – Functional and design specifications
3 Terms, definitions, abbreviations and symbols
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 61000-3-3,
IEC 61000-4-15 and the following apply.

– 8 – IEC TR 61547-1:2015 © IEC 2015
3.1.1
flicker
impression of unsteadiness of visual sensation induced by a light stimulus whose luminance
or spectral distribution fluctuates with time
[SOURCE: IEC 60050-845:1987, 845-02-49]
3.1.2
flickermeter
instrument designed to measure any quantity representative of flicker
[SOURCE: IEC 60050-604:1987, 604-01-28]
3.1.3
voltage flickermeter
instrument as specified in IEC 61000-4-15 which is designed to measure any quantity
representative of flicker resulting from mains voltage fluctuations
3.1.4
illuminance
quotient of the luminous flux dΦ incident on an element of the surface containing the point,
v
by the area dA of that element
Equivalent definition. Integral, taken over the hemisphere visible from the given point, of the
expression L •cos θ·dΩ where L is the luminance at the given point in the various directions
v v
of the incident elementary beams of solid angle dΩ, and θ is the angle between any of these
beams and the normal to the surface at the given point
dΦ
v
E = = L ⋅cosθ⋅ dΩ
v v
∫
2π sr
dA
–2
Note 1 to entry: Illuminance is expressed in lx or lm·m
[SOURCE: IEC 60050-845:1987, 845-01-38]
3.1.5
light flickermeter
instrument designed to measure flicker resulting from temporal changes in the intensity of the
light in an objective way and based on the IEC 61000-4-15 specifications
3.1.6
threshold of flicker irritability
maximum value of a fluctuation of luminance or of spectral distribution which gives rise to a
flicker tolerated without discomfort by a specified sample of the population
[SOURCE: IEC 60050-161:1990, 161-08-16]
3.1.7
short-term flicker indicator
P
st
measure of flicker evaluated over a specified time interval of a relatively short duration
definition
Note 1 to entry: The duration is typically 10 min, in accordance with IEC 61000-4-15.
[SOURCE: IEC 60050-161:1990, 161-08-18]

3.2 Abbreviations
a.c. alternating current
AM amplitude modulation
CFL compact fluorescent lamp
CIE Commission Internationale de l'Éclairage
cpm changes per minute
d.c. direct current
EUT equipment under test
EMC electromagnetic compatibility
EMI electromagnetic interference
Hz hertz
IEEE Institute of Electrical and Electronics Engineers
IEC International Electrotechnical Commission
IEV International Electrotechnical Vocabulary
ISO International Organization for Standardization
I-SH interpretation sheet
kHz kilohertz
LED light emitting diode
LP low pass
ms millisecond
rect rectangular
rms root mean square
TR technical report
SSL solid state lighting
V voltage
W watt
3.3 Symbols
α multiplication factor
C gain of the light amplifier
A
d relative voltage change
d  relative change of the rectangular modulation of the illuminance
E
d  relative change of the 100 Hz-illuminance ripple
r
∆u instantaneous total voltage variation after a voltage fluctuation,

∆U total voltage variation of the half-period rms value after a voltage fluctuation

f  mains frequency (50 Hz)
f  modulation frequency
m
m modulation index
% percent
pp percentage point
P short-term flicker indicator
st
E
P P -value of the standardised illuminance waveform E(t)
st
st
EUT
P P -value of the illuminance of an EUT measured with the light flickermeter
st
st
– 10 – IEC TR 61547-1:2015 © IEC 2015
LM
P P -value of the illuminance measured with the light flickermeter
st st
V
P P -value of the supply voltage measured with the voltage flickermeter
st st
LM
P light flicker noise level
st
noise
V
P P -noise level of the mains
st
st
noise
s the complex Laplace variable

ˆ
u amplitude of the mains voltage
u(t) mains voltage signal
u (t) output voltage of the light sensor amplifier
E
T modulation period
m
T period of time over which the illuminance is measured during application of the
test
voltage fluctuation
U half-period rms-value
4 General
The immunity of lighting equipment to voltage fluctuations may be tested by applying specific
types and levels of voltage fluctuations on the mains in accordance with the short-term flicker
indicator P = 1 curve for the reference incandescent lamp of 60 W specified in
st
IEC 61000-3-3. In this way, the full EMC approach is applied for flicker, i.e. voltage
fluctuations caused by equipment connected to the grid are limited by the voltage fluctuation
emission test of IEC 61000-3-3, while the level of flicker immunity of lighting equipment
against these P = 1 voltage fluctuations is tested using the method and procedures specified
st
in this technical report (see Figure 1).
During the test, the supply voltage is modulated with P = 1 fluctuation extracted from the
st
threshold of flicker irritability curve and the luminous intensity variation of the lighting
V
equipment is measured and recorded (denoted as ). A light flickermeter is applied to
P
st
LM V
measure the value of the metric P (denoted as P , whereas P would correspond to the
st st st
flicker severity value measured from voltage fluctuations).
5 Voltage fluctuation disturbance signal
5.1 General
The immunity test against voltage fluctuations is carried out in accordance with the test
method specified in Clause 6. The disturbances are rectangular amplitude modulations that
are to be applied on the a.c. power port.

Voltage flickermeter
voltage
Apply stable a.c. mains source via
U+∆U
reference impedance
EUT
measure
P
st
60 W
(60 W inc. lamp)
inc. lamp
Eye-brain
EUT = model
model
Apparatus
IEC
Figure 1a – Voltage fluctuation emission test IEC 61000-3-3,
using the IEC voltage flickermeter IEC 61000-4-15
Apply a.c. mains
light flickermeter
voltage fluctuation
L+∆L
EUT
corresponding to
light
P
st
(60 W inc. lamp) measure
Eye-brain
P
st
model
EUT = Lighting
60W
equipment
U+∆U
P =1
st
IEC
Figure 1b – Voltage fluctuation immunity test specified in this technical report
Figure 1 – The full EMC approach for mains voltage fluctuations
The mains signal is to be amplitude modulated with rectangular signals with frequencies
between approximately 0,05 Hz and 40 Hz. For the rectangular modulated mains signal u(t)
the following equation applies:
ˆ
u(t)= u⋅ sin(2πft)⋅{1+ m⋅ signum (sin(2πf t))}
(1)
m
where
ˆ
u is the amplitude of the mains voltage;
f is the mains frequency (50 Hz);
m is the modulation index;
signum(x) = the signum function, signum(x) = 1 for x > 0
signum(x) = 0 for x = 0
signum(x) = –1 for x <0
f is the modulation frequency = 1/T .
m m
Furthermore the half-period rms value U of the unmodulated mains signal can be written as:
ˆ
U= u / 2 (2)
In IEC 61000-4-15, the parameter d is applied, which is the total relative voltage change:
ˆ
d=∆u / u=∆U /U
, (3)
for rectangular AM modulation with modulation frequencies < f
where
– 12 – IEC TR 61547-1:2015 © IEC 2015
∆u is the instantaneous total voltage variation after a voltage fluctuation;
∆U is the total voltage variation of the half-period rms value after a voltage fluctuation.
For a rectangular modulated mains signal with modulation index m the relative voltage change
d is:
d = 2m. (4)
The relative voltage change (or voltage fluctuation) d is often expressed as a percentage.
An example of the parameters is shown in Figure 2.
Mains signal – rectangular amplitude modulation
ˆ
u
T
m
−100
u
(t)
−200
−300
230 V; 50 Hz; rectangular modulation 5 Hz; modulation index m = 0,1
−400
0 0,05 0,1 0,15 0,2 0,25 0,3 0,35 0,4 0,45 0,5
Time (s)
IEC
EXAMPLE Amplitude modulated mains signal (230 V; 50 Hz). Rectangular modulation; frequency 5 Hz (600 cpm);
T = 0,2 s; modulation index m = 0,1 (relative voltage change d = 20 %).
m
Figure 2 – Definition of the mains test signal including
a rectangular modulated voltage fluctuation (see Equation (1))
Voltage fluctuations frequencies are often expressed in terms of voltage changes per minute
(cpm). The relation between the voltage fluctuation frequency f and the cpm (one cycle
m
contains two changes) is:
f [Hz] = cpm [changes per minute] / 120. (5)
m
5.2 Mains signal parameters
The unmodulated test voltage level U should be set and maintained at the nominal value of
230 V, with a tolerance of ± 0,5 %.
The mains frequency f should be set and maintained with a tolerance of ± 0,5 % of the
nominal value of 50 Hz.
Residual fluctuations of the unmodulated test supply voltage during a test may give rise to P
st
that are not exactly zero. It is recommended to keep this P -noise level below 0,2. See
st
Clause B.5 for the impact on the uncertainty of the test.
Magnitude (V)
∆u
NOTE In IEC 61000-3-3 the P -noise level is specified to be less than 0,4 which can induce an uncertainty of 8 %
st
in the IEC 61000-4-15 measurement. However, in this test protocol there are many sources of uncertainty and that
is the reason to set a more strict P -noise level tolerance.
st
5.3 Disturbance signal parameters and test levels
Specific test frequencies and types of modulation are specified in the IEC flickermeter
standard IEC 61000-4-15 for performance verification purposes. It is recommended to use the
test frequencies and the rectangular modulation given in Table 5 of IEC 61000-4-15:2010 also
as test signals for voltage fluctuation immunity testing of lighting equipment.
The recommended specific levels of relative voltage changes and modulation frequencies to
be applied are given in Table 1. The test levels in this table are partly taken from the
flickermeter performance test specifications given in Table 5 of IEC 61000-4-15:2010, and
from the test level at 8,8 Hz given in Table 2b of IEC 61000-4-15:2010. The latter frequency is
the most sensitive frequency over the frequency range of interest.
The rectangular modulation pattern should be applied with a duty cycle of
50 % ± 2 percentage point (pp), and the transition time from one voltage level to the next
should be less than 0,5 ms. All test frequency and level combinations will give a short-term
V
flicker value of P = 1 corresponding to the threshold of the flicker irritability curve.
st
The duration of the voltage fluctuation applied to the EUT should be minimally 120 s (see
footnote c of Table 1).
Table 1 – Voltage fluctuations – Test specification of voltage
fluctuations applied at input a.c. power ports 230 V; 50 Hz
a c d
Rectangular amplitude modulations with duty cycle of 50 %
Voltage changes per minute Modulation frequency Relative voltage fluctuation
f d = ∆U/U
m
cpm Hz %
39 0,325 0 0,894
110 0,916 7 0,722
b
1 056 8,8 0,275
1 620 13,5 0,407
4 000 33,3 2,343
a
See Table 5 of IEC 61000-4-15:2010.
b
See Table 2b of IEC 61000-4-15:2010 for P = 1; the value of d = 0,196 % is increased to 0,275 % to give
inst
P = 1.
st
c
The duration of the voltage fluctuation and recording of the illuminance is recommended to be minimally 180
s (60 s for the transient response of the flickermeter’s filters and 120 s for the duration of the statistical
evaluation of the flicker level in block d, see A.2.5). First of all, the transient response of the light
flickermeter’s filters shall be considered, which is dominated by the illuminance adapter (block a, see A.2.2).
The time constant of this filter is set at 10 s, reaching the 90 % of the value corresponding to the steady
state response at approximately 50 s. In addition, the evaluation period should contain an integer number of
voltage fluctuation periods. For the set of test modulation frequencies given in this table, the minimum
duration to achieve an integer number of voltage fluctuation periods in all the test cases is 120 s.
d
Recommended absolute tolerance for the duty cycle is ±2 pp, for the modulation frequency the
recommended tolerance is ±1 % and for the relative voltage fluctuation the recommended tolerance is ±2 %

– 14 – IEC TR 61547-1:2015 © IEC 2015
6 Test setup and equipment
6.1 General
The block diagram of the test setup is shown in Figure 3. One can distinguish three parts in
the setup:
a) generation of the test voltage,
b) application of the test voltage to the EUT, photometric measurement of the EUT in an
optically shielded environment,
c) measurement and control equipment.
More details of the equipment properties are described below.
Photometric
measurement in
optically shielded
Generation test voltage:
environment
mains voltage including voltage fluctuation
Mains frequency +
Gain
modulation
EUT
u(t)
Test waveform
Lamp/luminaire
Amplifier
generator
under test
E(t)
Measurement equipment:
light flickermeter
Light sensor +
transimpedance
Computation of the flicker
Measurement of test
amplifier
V LM
voltage & relative
metrics ( P , P )
st st
illuminance
Measurement relative
illuminance
Data processing
Data acquisition
u (t)
E
IEC
Figure 3 – Block diagram voltage-fluctuation immunity test
6.2 Test voltage
The test voltage, which consists of the mains voltage with a rectangular amplitude modulation,
can be synthesised using waveform generator and an amplifier. This may be implemented
also by using a separate waveform generator for the modulating signal that is applied to a
generator that makes the 50 Hz mains signal.
It is important that the equipment for generating the amplitude modulation is capable of
generating voltage fluctuations well below the lowest test level of d = 0,275 % at 8,8 Hz (see
Table 1).
Care should be taken that no other disturbing signals than the amplitude modulation are
present (see 5.2 and 7.4.3 for the verification).

The characteristics of the test voltage should be verified by either measurement through an
oscilloscope or by direct application of an IEC flickermeter (see 7.3.2).
6.3 Optical test environment
The illuminance of the EUT is to be measured for processing by the light flickermeter. There
is no need for measuring the absolute value. Only the relative illuminance is to be determined.
The EUT and the light sensor are to be located in an optically shielded environment to avoid
disturbances from light sources other than the EUT.
The test environment should be also mechanically robust to avoid vibrations of the EUT and
light sensor that may give rise to unwanted variations in the illuminance.
It is recommended that the light output of the EUT is measured indirectly via a reflecting
surface. This is especially true for lighting equipment with a spatial distribution of light
sources (e.g. TL, TLED, 2D LED matrix).
An integrating sphere, like an Ulbricht sphere, may be applied. This may be convenient
because then the orientation and alignment of the EUT with respect to the light sensor is less
critical.
6.4 Light sensor and amplifier
A photodiode with a filter and an appropriate amplifier is to be applied for measuring the
illuminance (or more specific: the relative illuminance) of the EUT.
The photodiode, optical filter and amplifier combination should satisfy the following
characteristics:
a) the optical filter should match the photodiode to the eye sensitivity curve of CIE 1931
which is the CIE 1931 Standard Observer function specified in ISO 11664-1:2007 [3];
b) the cut-off frequency of the amplifier should enable measurement of all flicker-relevant
frequencies. A cut-off frequency of 2 kHz is recommended;
c) the output voltage of the amplifier should vary linearly with the illuminance and no offset-
voltage should be present.
6.5 Signals to be measured
The output voltage u (t) of the light sensor amplifier is measured as a function of time over a
E
period T . The output voltage u (t) varies linearly with the illuminance E(t):
test E
u (t)= C ⋅ E(t) is measured between 0< t< T (6)
E A test
where C is the constant including the gain of the amplifier and which relates the output
A
voltage of the light sensor amplifier to the illuminance.
In addition, the mains voltage including the voltage variation u(t) is measured over the same
time period.
The signals can be measured with an oscilloscope. It is recommended to apply an appropriate
low-pass filter in the oscilloscope to limit the noise.
___________
Numbers in square brackets refer to the Bibliography.

– 16 – IEC TR 61547-1:2015 © IEC 2015
The measured signals are to be recorded for further processing.
6.6 Signal processing
6.6.1 Anti-aliasing filter
The light output of some types of lamps may contain spectral components at frequencies well
above 100 Hz (kHz-range) that are not producing visible flicker. Depending on the sampling
frequency (see 6.6.2) these higher frequency components may be undersampled and this may
lead to aliasing which gives artefacts in the light sensor signal. It is recommended to avoid
such aliasing effects by application of a low-pass filter between the amplifier output of the
light sensor and the measurement system.
st
EXAMPLE A 1 order low-pass filter with 3 dB cut-off frequency of 1 kHz will attenuate a factor 10 at 3 kHz. For
3 kHz, the sampling frequency is then at least 6 kHz.
6.6.2 Sampling frequency
For processing of the signals, in accordance with the Nyquist criterion, the sampling
frequency shall be at least twice the bandwidth of the signal, which is approximately twice the
highest frequency within the signal to be measured.
The mains voltage signal of 50 Hz with amplitude modulation ranging from 0,5 Hz up to 40 Hz
has a spectrum of interest up to the sum of the mains and the modulation frequency. Hence,
the frequency range of interest of the mains voltage signal extends roughly up to 100 Hz.
The illuminance signal has a spectrum of interest that is at least twice the spectrum of the
mains signal for incandescent lamps. For non-incandescent type of lighting equipment much
higher frequencies may be present depending on the driver technology applied. As these
much higher frequencies are not of interest for flicker these should be filtered before sampling
(see 6.6.1).
Interharmonics may also cause beat frequencies that may produce light flicker.
Still for calculating flicker, the highest frequency of interest is determined by the highest
modulation frequency, the mains frequency and the possible interharmonics. The
flickermeter, and also the light flickermeter contain a bandpass filter (0,05 Hz to 35 Hz), see
Annex A.
Although the highest frequency of interest in the illuminance signal is limited to approximately
200 Hz, the way the various digital filters are implemented usually requires oversampling and
therefore much higher sampling rates (see [9][12]).
For the Matlab implantation of the IEC flickermeter given in [14] a sampling rate of at least
2 kHz is recommended. Therefore, for the light flickermeter a sampling rate of at least 4 kHz
is recommended as the bandwidth of the illuminance signal resulting from the mains voltage
and its fluctuations is approximately twice the bandwidth of the mains signal. As explained in
6.6.1, the sampling frequency shall be selected also in conjunction with the cut-off frequency
of the anti-aliasing filter applied. For practical low-pass filters with a cut-off frequency around
1 kHz, a sample rate of at least 10 kHz is recommended.
An example of a recorded illuminance signal over a period of 1 s is given in Figure 4. The
100 Hz ripple, which is typical for an incandescent lamp, and the additional modulation
resulting from the amplitude modulation of the mains voltage at 8,8 Hz (d = 0,275 %) are
clearly visible.
60 W incandescent lamp: mains 230 V/50 Hz and rectangular amplitude modulation 8,8 Hz and 0,275%
−100
−200
−300
−400
0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1
IEC
Time (s)
a) Mains voltage fluctuation with rectangular modulated of 8,8 Hz and d = 0,275 %
60 W incandescent lamp: mains 230 V/50 Hz and rectangular amplitude modulation 8,8 Hz and 0,275%
1,15
1,1
1,05
0,95
0,9
0,85
0,8
0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1
Time (s) IEC
b) Illuminance signal of a 60 W incandescent lamp including a 100 Hz ripple
and an additional modulation due to the modulated mains voltage fluctuation (a)
60 W incandescent lamp: mains 230 V/50 Hz and rectangular amplitude modulation 8,8 Hz and 0,275%
0,8
0,6
0,4
0,2
0 0,02 0,04 0,06 0,08 0,1 0,12 0,14 0,16 0,18 0,2
IEC
Time (s)
c) Same as b) zoomed over 0,2 s and vertical range from 0 to 1,2
Figure 4 – Example of a recorded mains voltage fluctuation
and illuminance signal of a 60 W incandescent lamp
Mains voltage including amplitude modulation (V)
Relative illuminance
Relative illuminance
...