Equipment for general lighting purposes - Objective test method for stroboscopic effects of lighting equipment

IEC TR 63158:2018(E) describes an objective stroboscopic effect visibility (SVM) meter, which can be applied for performance testing of lighting equipment under different operational conditions.
The stroboscopic effects considered in this document are limited to the objective assessment by a human observer of visible stroboscopic effects of temporal light modulation of lighting equipment in general indoor applications, with typical indoor light levels (> 100 lx) and with moderate movements of an observer or nearby handled object ( The contents of the corrigendum of July 2018 have been included in this copy.

General Information

Status
Published
Publication Date
18-Mar-2018
Technical Committee
Current Stage
PPUB - Publication issued
Start Date
19-Mar-2018
Completion Date
19-Mar-2018
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IEC TR 63158
Edition 1.0 2018-03
TECHNICAL
REPORT
colour
inside
Equipment for general lighting purposes – Objective test method for
stroboscopic effects of lighting equipment
IEC TR 63158:2018-03(en)
---------------------- Page: 1 ----------------------
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---------------------- Page: 2 ----------------------
IEC TR 63158
Edition 1.0 2018-03
TECHNICAL
REPORT
colour
inside
Equipment for general lighting purposes – Objective test method for
stroboscopic effects of lighting equipment
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.140.01 ISBN 978-2-8322-5488-2

Warning! Make sure that you obtained this publication from an authorized distributor.

® Registered trademark of the International Electrotechnical Commission
---------------------- Page: 3 ----------------------
– 2 – IEC TR 63158:2018 © IEC 2018
CONTENTS

FOREWORD ........................................................................................................................... 4

INTRODUCTION ..................................................................................................................... 6

1 Scope .............................................................................................................................. 7

2 Normative references ...................................................................................................... 7

3 Terms, definitions, abbreviated terms and symbols .......................................................... 7

3.1 Terms and definitions .............................................................................................. 7

3.2 Abbreviated terms ................................................................................................... 9

3.3 Symbols ................................................................................................................ 10

4 General ......................................................................................................................... 10

5 Laboratory and equipment requirements ........................................................................ 11

5.1 Schematic of the measurement setup ................................................................... 11

5.2 Laboratory and environmental conditions .............................................................. 12

5.3 Electrical power source ......................................................................................... 12

5.4 Optical test environment ....................................................................................... 12

5.5 Light sensor and amplifier ..................................................................................... 13

5.6 Signals to be measured ........................................................................................ 13

5.7 Duration of the measurement ................................................................................ 13

5.8 Signal processing ................................................................................................. 13

5.8.1 Anti-aliasing filter ........................................................................................... 13

5.8.2 Sampling frequency ....................................................................................... 14

5.8.3 Signal resolution ............................................................................................ 14

5.9 SVM calculation .................................................................................................... 14

5.10 Verification noise-level of the setup ...................................................................... 14

6 Stroboscopic effect visibility meter ................................................................................. 15

6.1 General ................................................................................................................. 15

6.2 Verification............................................................................................................ 15

6.3 Evaluation of results ............................................................................................. 15

7 Test setup and operating conditions .............................................................................. 16

7.1 General ................................................................................................................. 16

7.2 Ageing .................................................................................................................. 16

7.3 Mounting ............................................................................................................... 16

7.4 Stabilization before measurement ......................................................................... 16

7.5 Operation .............................................................................................................. 16

8 General test procedure .................................................................................................. 16

9 Application-specific equipment, procedures and conditions ............................................ 17

9.1 General ................................................................................................................. 17

9.2 Phase cut dimmer compatibility test of lighting equipment ..................................... 17

9.3 Controlgear testing ............................................................................................... 17

9.4 In-situ testing ........................................................................................................ 18

10 Test report ..................................................................................................................... 18

11 Measurement uncertainties ............................................................................................ 18

11.1 General ................................................................................................................. 18

11.2 Verification tests ................................................................................................... 18

11.2.1 General ......................................................................................................... 18

11.2.2 Stroboscopic effect visibility meter ................................................................. 18

11.2.3 Electrical power source parameters ............................................................... 18

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IEC TR 63158:2018 © IEC 2018 – 3 –

11.2.4 Electromagnetic compatibility and test environment ....................................... 19

11.2.5 Light sensor and amplifier .............................................................................. 19

11.2.6 Overall noise-level of the setup...................................................................... 19

11.2.7 Repeatability ................................................................................................. 19

11.3 Quality assurance ................................................................................................. 19

Annex A (normative) Specification of the stroboscopic effect visibility meter ........................ 20

A.1 Background........................................................................................................... 20

A.2 Detailed specifications of the stroboscopic effect meter ........................................ 21

A.2.1 Schematic of the SVM meter.......................................................................... 21

A.2.2 Block a: illuminance adapter .......................................................................... 21

A.2.3 Block b: calculation of spectrum .................................................................... 22

A.2.4 Block c: weighting with the stroboscopic effect sensitivity curve ..................... 22

A.2.5 Block d: summation of the weighted spectrum ............................................... 22

A.3 Numerical implementation of SVM ........................................................................ 23

A.4 Example................................................................................................................ 24

A.5 Verification waveform of the stroboscopic effect meter .......................................... 24

A.6 Example of SVM implementation in MATLAB ...................................................... 27

Annex B (informative) Uncertainty considerations ................................................................ 28

B.1 General ................................................................................................................. 28

B.2 General symbols ................................................................................................... 28

B.3 Measurand ............................................................................................................ 28

B.4 Influence quantities ............................................................................................... 28

Annex C (informative) Examples of test results .................................................................... 31

C.1 SVM measurement results of conventional lighting equipment .............................. 31

C.2 SVM test under dimming conditions ...................................................................... 32

Bibliography .......................................................................................................................... 34

Figure 1 – Schematic of the stroboscopic effect measurement method ................................. 10

Figure 2 – Different possible applications for an SVM test .................................................... 11

Figure 3 – Schematic of the TLA measurement method ........................................................ 12

Figure 4 – Dimmer compatibility testing ................................................................................ 17

Figure 5 – Controlgear testing ............................................................................................... 17

Figure A.1 – Structure of the stroboscopic effect visibility meter ........................................... 21

Figure A.2 – SVM sensitivity threshold T ............................................................................... 23

Figure A.3 – Example of an illuminance signal with a ripple .................................................. 26

Figure B.1 – Fishbone diagram representing the categories of influence quantities

contributing to the uncertainty of the SVM measurement ....................................................... 29

Figure C.1 – Normalized light ripple of conventional lighting equipment ................................ 32

Figure C.2 – Graphical SVM results of four samples of lighting equipment under

dimming conditions ............................................................................................................... 33

Table A.1 – Specification of the parameters of the verification waveforms ............................ 27

Table B.1 – Influence quantities and their recommended tolerances ..................................... 30

Table C.1 – Numerical results of SVM calculations of conventional lighting equipment ......... 31

Table C.2 – Numerical results of SVM calculations of four samples of lighting

equipment under dimming conditions .................................................................................... 33

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– 4 – IEC TR 63158:2018 © IEC 2018
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
EQUIPMENT FOR GENERAL LIGHTING PURPOSES –
OBJECTIVE TEST METHOD FOR STROBOSCOPIC
EFFECTS OF LIGHTING EQUIPMENT
FOREWORD

1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising

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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 63158, which is a Technical Report, has been prepared by IEC technical committee

34: Lamps and related equipment.
The text of this Technical Report is based on the following documents:
Draft TR Report on voting
34/436/DTR 34/496/RVDTR

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.
---------------------- Page: 6 ----------------------
IEC TR 63158:2018 © IEC 2018 – 5 –

This document has been drafted in accordance with the ISO/IEC Directives, Part 2.

The committee has decided that the contents of this document will remain unchanged until the

stability date indicated on the IEC website under "http://webstore.iec.ch" in the data related to

the specific document. At this date, the document will be
 reconfirmed,
 withdrawn,
 replaced by a revised edition, or
 amended.
A bilingual version of this publication may be issued at a later date.
The contents of the corrigendum of July 2018 have been included in this copy.

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.
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– 6 – IEC TR 63158:2018 © IEC 2018
INTRODUCTION

The fast rate at which solid state light (SSL) sources can change their intensity is one of the

main drivers behind the revolution in the lighting world and applications of lighting. Linked to

the fast rate of the intensity change is a direct transfer of the modulation of the driving

current, both intended and unintended, to a modulation of the luminous flux. This light

modulation can give rise to changes in the perception of the environment. While in some very

specific entertainment, scientific or industrial applications a change of perception due to light

modulation is desired, for most everyday applications and activities the change is detrimental

and undesired. The general term used for these changes in the perception of the environment

is “temporal light artefacts” (TLAs) and these can have a large influence on the judgment of

the light quality. Moreover, the visible modulation of light can lead to a decrease in

performance, increased fatigue as well as acute health problems like epileptic seizures and

migraine episodes [1][3] .

Different terms exist to describe the different types of TLAs that may be perceived by humans.

The term ‘flicker’ refers to light variation that may be directly perceived by an observer.

‘Stroboscopic effect’ is an effect which may become visible for an observer when a moving or

rotating object is illuminated (CIE TN 006:2016).

Possible causes for light modulation of lighting equipment that may give rise to flicker or

stroboscopic effect are:
– AC supply combined with light source technology and its controlgear topology;

– dimming technology of externally applied dimmers or internal light level regulators;

– mains voltage fluctuations caused by electrical apparatus connected to the mains

(conducted electromagnetic disturbances) or intentionally applied for mains-signalling

purposes.

Lighting products that show unacceptable stroboscopic effect are considered as poor quality

lighting.

Until recently, modulation depth (MD) – also called percent flicker – and flicker index (FI) were

often used to quantify flicker or stroboscopic effect. It has been shown that both these metrics

are not able to objectively score the level of flicker or stroboscopic effect as actually

perceived by humans [1]. Therefore, instead of MD and FI, for ‘flicker’ the IEC-standardized

) is used, which is derived from the widely applied and
‘short-term flicker severity’ ( P

accepted IEC-standardized P -metric to assess the impact of voltage fluctuations on flicker

[5]. For the objective assessment of stroboscopic effect, the stroboscopic effect visibility

measure (SVM) is available [6].

In 2013, a clear need was identified for an objective test method for testing lighting equipment

against flicker caused by voltage fluctuations induced by switching loads such as household

appliances. Technical committee 34 developed and verified an objective test method for

flicker using the flicker metric P . This objective flicker test method is described in

IEC TR 61547-1 [5].

In recent years the interest in objective testing of stroboscopic effect has also increased

considerably. In the near future, CIE will start developing a basic standard on TLA metrology

including objective test methods for flicker and stroboscopic effect.

This document provides practical considerations and application examples on how to

objectively quantify the stroboscopic effect performance of lighting equipment in terms of

SVM.
______________
Numbers in square brackets refer to the Bibliography.
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IEC TR 63158:2018 © IEC 2018 – 7 –
EQUIPMENT FOR GENERAL LIGHTING PURPOSES –
OBJECTIVE TEST METHOD FOR STROBOSCOPIC
EFFECTS OF LIGHTING EQUIPMENT
1 Scope

This document describes an objective stroboscopic effect visibility (SVM) meter, which can be

applied for performance testing of lighting equipment under different operational conditions.

The stroboscopic effects considered in this document are limited to the objective assessment

by a human observer of visible stroboscopic effects of temporal light modulation of lighting

equipment in general indoor applications, with typical indoor light levels (> 100 lx) and with

moderate movements of an observer or nearby handled object (< 4 m/s). Details on restriction

of the applicability of the stroboscopic effect visibility measure is given in Clause A.1.

For assessing unwanted stroboscopic effects in other applications, such as the misperception

of rapidly rotating or moving machinery in an industrial environment for example, other

metrics and methods can be required.

The object of this document is to establish a common and objective reference for evaluating

the performance of lighting equipment in terms of stroboscopic effect. Temporal changes in

the colour of the light (chromatic effects) are not considered in this test. This document

describes the methodology for SVM and does not define any limits.
The objective method and procedure described in this document are based on
CIE TN 006:2016 on temporal light artefacts (TLAs).

The method described in this document can be applied to objectively assess the stroboscopic

effect of lighting equipment that is powered from any type of source, AC mains, DC mains,

battery fed or fed through an external dimmer.
2 Normative references
There are no normative references in this document.
3 Terms, definitions, abbreviated terms and symbols
3.1 Terms and definitions
For the purposes of this document, the following terms and definitions 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
auxiliary equipment
AuxEq
peripheral equipment that is part of the system under test
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– 8 – IEC TR 63158:2018 © IEC 2018
3.1.2
equipment-under-test
EUT
equipment subjected to stroboscopic visibility tests
3.1.3
temporal light artefact
TLA

change in visual perception, induced by a light stimulus the luminance or spectral distribution

of which fluctuates with time, for a human observer in a specified environment

Note 1 to entry: The change of visual perception is a result of comparing the visual perception of the environment

lit by the modulated light to the visual perception of the same person in the same environment, when the

environment is lit by non-modulated light.
[SOURCE: CIE TN 006:2016, 2.4.1]
3.1.4
flicker

perception of visual unsteadiness induced by a light stimulus the luminance or spectral

distribution of which fluctuates with time, for a static observer in a static environment

Note 1 to entry: The fluctuations of the light stimulus with time include periodic and non-periodic fluctuations and

may be induced by the light source itself, the power source or other influencing factors.

Note 2 to entry: Flicker is a type of temporal light artefact.
[SOURCE: CIE TN 006:2016, 2.4.2, modified – Note 3 has been deleted.]
3.1.5
stroboscopic effect

change in motion perception induced by a light stimulus the luminance or spectral distribution

of which fluctuates with time, for a static observer in a non-static environment

EXAMPLE 1 For a square periodic luminance fluctuation, moving objects are perceived to move discretely rather

than continuously.

EXAMPLE 2 If the frequency of a periodic luminance fluctuation coincides with the frequency of a rotating object,

the rotating object is perceived as static.
Note 1 to entry: The stroboscopic effect is a type of temporal light artefact.
[SOURCE: CIE TN 006:2016, 2.4.3]
3.1.6
static observer
observer who does not move her/his eye(s)

Note 1 to entry: Only large eye movements (saccades) fall under this definition. An observer who only does

involuntary micro-saccades is considered static.
[SOURCE: CIE TN 006:2016, 2.4.5]
3.1.7
static environment

environment that does not contain perceivable motion under non-modulated lighting

conditions
[SOURCE: CIE TN 006:2016, 2.4.6]
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IEC TR 63158:2018 © IEC 2018 – 9 –
3.1.8
average observer

observer representing the mean characteristics of a specified population of sighted individuals

Note 1 to entry: The population in question depends on the application a lighting system is designed for. It can

also include specific groups of observers as for example migraine sufferers. A general average observer is based

on data aggregated across gender and age but specific observers can be defined for subgroups.

[SOURCE: CIE TN 006:2016, 2.3.1]
3.1.9
visible artefact

perceptual effect of a light modulation detected by an average observer with a probability

higher than 50 %
[SOURCE: CIE TN 006:2016, 2.3.2]
3.1.10
visibility threshold

level of light modulation, at which an average observer, when presented with and questioned

about the visibility of an artefact, can detect the artefact with a probability of 50 %

[SOURCE: CIE TN 006:2016, 2.3.3]
3.1.11
stroboscopic effect visibility

measuremeasure of stroboscopic effect evaluated over a specified time interval of a relatively

short duration
Note 1 to entry: The duration is typically 1 s, in accordance with CIE TN 006.
3.1.12
modulation depth

property of waveform calculated by taking the ratio of the difference between the maximum

and minimum intensity to the sum of the maximum and minimum intensity

Note 1 to entry: Often, MD is calculated over one fundamental period of waveform modulation, however it can be

calculated also over a much longer time over a multiple number of periods.

Note 2 to entry: MD is also often expressed as a percentage, by multiplying the ratio by 100 %.

3.2 Abbreviated terms
AC alternating current
ADC analog to digital converter
CIE Commission Internationale de l'Éclairage
DC direct current
DFT discreet Fourier transform
EUT equipment under test
FFT fast Fourier transform
Hz hertz
IEEE Institute of Electrical and Electronics Engineers
kHz kilohertz
LED light emitting diode
MD modu
...

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