IEC 62504:2014

IEC 62504 ®
Edition 1.0 2014-06
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
General lighting – Light emitting diode (LED) products and related equipment –
Terms and definitions
Éclairage général – Produits à diode électroluminescente (LED) et équipements
associés – Termes et définitions

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IEC 62504 ®
Edition 1.0 2014-06
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
General lighting – Light emitting diode (LED) products and related equipment –

Terms and definitions
Éclairage général – Produits à diode électroluminescente (LED) et équipements

associés – Termes et définitions

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX T
ICS 29.140.20 ISBN 978-2-8322-1651-4

– 2 – IEC 62504:2014 © IEC 2014
CONTENTS
FOREWORD . 3
INTRODUCTION . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
Annex A (informative) Overview of LED products and terms under consideration . 18
A.1 Overview of LED packages . 18
A.2 Overview of systems composed of LED light sources and LED controlgear . 19
A.3 Overview of LED light sources . 20
A.3.1 Examples of retrofit LED lamps – White or coloured light, bulb or
reflector type, with caps according IEC 60061 (as shown in Figures A.3
and A.4) . 20
A.3.2 Examples of LED lamps with new shapes . 20
A.3.3 Examples of LED modules . 20
A.4 Terms under consideration . 21
A.4.1 LED light engine . 21
A.4.2 Chip on board (CoB) . 21
A.5 Schematic of built-in, independent, integral LED module . 22
A.6 LED product tree overview . 22
Bibliography . 24

Figure 1 – Schematic drawing of the chain of thermal resistors . 17
Figure A.1 – Overview of LED packages . 18
Figure A.2 – Overview of systems composed of LED light sources and LED controlgear . 19
Figure A.3 – Examples of retrofit LED lamps . 20
Figure A.4 – Examples of LED lamps with new shapes . 20
Figure A.5 – Examples of LEDni modules . 21
Figure A.6 – Examples of chip on board . 22
Figure A.7 – Schematic of built in, independent, integral modules . 22
Figure A.8 – LED product tree overview . 23

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
GENERAL LIGHTING – LIGHT EMITTING DIODE (LED) PRODUCTS
AND RELATED EQUIPMENT – TERMS AND DEFINITIONS

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
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2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
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3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
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6) All users should ensure that they have the latest edition of this publication.
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 62504 has been prepared by IEC technical committee 34: Lamps
and related equipment in collaboration with representatives from CIE.
This first edition cancels and replaces the IEC TS 62504 published in 2011.
The significant changes with respect to IEC TS 62504 are as follows:
a) Terms from the International Electrotechnical Vocabulary that have not been modified are
deleted.
b) Alignment with the CIE has been done.
c) An introduction has been added

– 4 – IEC 62504:2014 © IEC 2014
The text of this standard is based on the following documents:
FDIS Report on voting
34/200/FDIS 34/205/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
The committee has decided that the contents of this publication will remain unchanged until
the stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data
related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
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.
INTRODUCTION
0.1 Principles of this International Standard
This document is based on IEC TS 62504:2011, General Lighting – LEDs and LED modules –
Terms and definitions, which was under the responsibility of SC 34A but this revision as
International Standard IEC 62504 transfers responsibility to TC 34.
The objective of this introduction is to help the reader to understand which terms are included
and to have an understanding of the LED product overview.
Compared with IEC TS 62504, the main changes are as follows.
0.2 Terms to include
General lighting terms in IEC 60050-845:1987, International Electrotechnical Vocabulary that
have not been modified will not be included in this standard.
Alignment with CIE is done. IEC will be the reference for products and related equipment and
CIE for lighting terminology. Alignment with ANSI RP16-10, Chapter 6.8 was also considered.
The terms included are as far as possible used in LED standards and manufacturers'
literature.,
Process to update IEC 60050-845:1987, the International Electrotechnical Vocabulary for
definitions that will be considered as relevant is underway in IEC TC34.
0.3 Alphabetic sequence
In order to find the term in a logical sequence, we have grouped similar terms of a product,
example:
LED lamp
– integrated LED lamp ,
– non-integrated LED lamp .
For each term, reference is made to the relevant standard if appropriate.
0.4 LED product tree:
The sequence from the first component, the LED die up to the LED luminaire is drawn.
The term LED does not represent a product, so no technical data can be linked to the term
LED.
– 6 – IEC 62504:2014 © IEC 2014
GENERAL LIGHTING – LIGHT EMITTING DIODE (LED) PRODUCTS
AND RELATED EQUIPMENT – TERMS AND DEFINITIONS

1 Scope
This International Standard IEC 62504 is of assistance in the common understanding of terms
and definitions, relevant for general lighting with LED technology. The terms included are
those already available in IEC LED standards or used in manufacturers' literature.
This standard provides descriptive terms (like “LED light sources”) and measurable terms
when modified from IEC 60050-845 (like “colour rendering index”).
NOTE Annex A gives overviews of LED package design and systems composed of LED light sources and
controlgear.
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 60050 (all parts), International Electrotechnical Vocabulary (available at
).
CIE Technical Report 127:2007, Measurement of LEDs
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60050-845, with the
exception of those modified below, and the following apply.
3.1
ageing
preconditioning period of the LED light source before initial values are taken
3.2
angular subtense
α
angle subtended by an apparent source as viewed from a point in space
Note 1 to entry: Angular subtense is expressed in radians (rad).
Note 2 to entry: The angle extension is determined by the observation distance, but at no distance smaller than
the minimum distance of accommodation of the eye.
Note 3 to entry: The location and angular subtense of the apparent source depends on the viewing position in the
beam.
Note 4 to entry: The angular subtense of an apparent source is only applicable in the wavelength range from
380 nm to1 400 nm.
Note 5 to entry: IEC TR 62778 gives additional information with regards to beam divergence.

[SOURCE: IEC 60825-1, 3.7, modified – Notes 1, 2 and 5 to entry are added and in the note 4
to entry the value of the wavelength range has been changed from '400 nm to 1 400 nm' to
'380 nm to 1 400 nm'; IEC 62471, 3.2, modified.]
3.3
apparent source
for a given evaluation location of the retinal hazard, the real or virtual object that forms the
smallest possible retinal image (considering the accommodation range of the human eye)
Note 1 to entry: The accommodation range of the eye is assumed to be variable from 100 mm to infinity. The
location of the apparent source for a given viewing position in the beam is that location to which the eye
accommodates to produce the most hazardous retinal irradiance condition.
Note 2 to entry: This definition is used to determine, for a given evaluation position, the location of the apparent
origin of laser radiation in the wavelength range of 380 nm to 1 400 nm. In the limit of vanishing divergence, i.e. in
the case of a well collimated beam, the location of the apparent source goes to infinity.
[SOURCE: IEC 60825-1, 3.10, modified – In the note 2 to entry the value of the wavelength
range is changed from '400 nm to 1 400 nm' to '380 nm to 1 400 nm'.]
3.4
beam angle
angle between two imaginary lines in a plane through the optical beam axis, such that these
lines pass through the centre of the front face of the lamp and through points at which the
luminous intensity is 50 % of the centre beam intensity
Note 1 to entry: Beam angle is expressed in degrees ( ° ).
Note 2 to entry: This angle is a full angle measure, not a half angle measure.
[SOURCE: IEC TR 61341, 2.4, modified, – The notes to entry are added.]
3.5
bin
restricted range of LED performance characteristics used to delimit a subset of LED dies or
LED packages near a nominal LED performance as identified by chromaticity, photometric,
radiometric and/or electrical characteristics
3.6 controlgear
3.6.1
controlgear for LED module
LED controlgear
unit inserted between the electrical supply and one or more LED modules, which serves to
supply the LED module(s) with its (their) rated voltage or rated current, and may consist of
one or more separate components and may include means for dimming, correcting the power
factor and suppressing radio interference, and further control functions
Note 1 to entry: The controlgear consists of a power supply and a control unit.
Note 2 to entry: The controlgear may be partly or totally integrated in the LED module.
Note 3 to entry: When no confusion is expected like when used in a LED standard for example, “controlgear” may
also be used. Both terms “controlgear” or “control gear” are acceptable.
[SOURCE: IEC 61347-2-13, 3.1, modified – The word 'electronic' is deleted from the term and
the words “further control functions” and the notes to entry are added.]
3.6.2
power supply of the controlgear
electronic device, being part of the controlgear, capable of controlling current, voltage or
power within design limits, containing no additional LED control capabilities

– 8 – IEC 62504:2014 © IEC 2014
Note 1 to entry: For LEDsi modules, the power supply of the controlgear is separate from the LED module on a
distant location.
Note 2 to entry: The energy source of a power supply can be either a battery or the electrical supply system.
3.6.3
control unit of the controlgear
electronic device, being part of the controlgear, responsible for controlling the electrical
energy to the LED light sources as well as colour mixing, response to depreciating luminous
flux and further performance features
Note 1 to entry: In LEDsi modules, the control unit of the controlgear is on board of the LED module and separate
from the power supply of the controlgear.
3.7
dominant wavelength
λ
d
wavelength of the monochromatic stimulus that, when additively mixed in suitable proportions
with the specified achromatic stimulus, matches the colour stimulus considered in the
CIE 1931 x,y chromaticity diagram
Note 1 to entry: Dominant wavelength is expressed in nanometres (nm).
Note 2 to entry: In the case of purple stimuli, the dominant wavelength is replaced by the complementary
wavelength.
Note 3 to entry: For characterising LED light sources the reference achromatic stimulus should be illuminant E
which has the chromaticity coordinates x = 0,3333, y = 0,3333.
E E
Note 4 to entry: A value for dominant wavelength should only be stated for LED light sources emitting coloured
light. For LED light sources emitting white light no meaningful value for dominant wavelength can be given.
Note 5 to entry: Figure 12 in CIE 127:2007 shows the relationship between chromaticity coordinate C of LED light
sources and value of dominant wavelength D. N is the chromaticity coordinate of achromatic stimulus E.
Note 6 to entry: Deviating from the peak wavelength, the dominant wavelength determines perceived colour.
[SOURCE: IEC 60050-845:1987, 845.03.44, modified – The words 'in the CIE 1931 x,y
chromaticity diagram' and the notes to entry 3 to 6 have been added; CIE S 017/E:2011, 17-
345, modified – The notes to entry 3 to 6 have been added.]
3.8
failure
termination of the ability of an item to perform a required function
Note 1 to entry: After failure the item has a fault.
Note 2 to entry: "Failure" is an event, as distinguished from "fault", which is a state.
Note 3 to entry: This concept as defined does not apply to items consisting of software only.
[SOURCE: IEC 60050-191, 191.04.01]
3.9
failure fraction
F
fraction of the population that lost the ability to perform a required function in a specified time
interval
Note 1 to entry: Failure fraction is dimensionless.
3.10
failure fraction at rated life
F
y
ratio y of failed LED products of the same type at their rated life to the test quantity

Note 1 to entry: The ratio is expressed in percent.
Note 2 to entry: This failure fraction expresses the combined effect of all components of a LED product including
mechanical, as far as the light output is concerned. The effect of the LED could either be less light than claimed or
no light at all.
Note 3 to entry: For LED products normally a failure fraction of 10% or/and 50% are being applied, indicated as
F and/or F .
10 50
3.11
family
group of LED light sources or LED luminaires, having the same characteristics and method of
control (integrated, semi-integrated, non integrated), the groups are distinguished by common
features of materials, components, and/or method of processing
3.12
forward direction
direction of current that results when the P-type semiconductor region connected to one
terminal is at positive potential relative to the N-type region connected to the other terminal
Note 1 to entry: If temperature compensation diodes are included, these are ignored in the determination of
forward direction.
[SOURCE: IEC 60050-521, 521.05.03, modified – The words 'connected to one terminal',
'potential' and 'connected to the other terminal' as well as note 1 to entry have been added.]
3.13
forward voltage
U
F
potential difference pertaining to the forward direction, dependent on the forward current at a
given temperature
Note 1 to entry: Forward voltage is expressed in Volts (V).
Note 2 to entry: Forward voltage for LED die is measured normally at 25 °C ambient temperature.
3.14
heat output to the luminaire
P
d
power to be transferred to the luminaire by means of heat-conduction in order to stay below
the t or t temperature
c p
Note 1 to entry: Heat output is expressed in Watts (W).
Note 2 to entry: P is below the rated power of a LED module.
d
Note 3 to entry: For LED modules which do not need heat-conduction to the luminaire for keeping t , P is equal
c d
to zero.
Note 4 to entry: A measurement method is under consideration.
3.15 LED lamp
LED light source provided with (a) cap(s) incorporating one or more LED module(s) and
possibly including one or more of the following; electrical, optical, mechanical, and thermal
components, interfaces and controlgear
Note 1 to entry: A LED lamp may be integrated (LEDi lamp) or semi-integrated (LEDsi lamp) or non-integrated
(LEDni lamp).
Note 2 to entry: Single and double-capped lamps are included.
Note 3 to entry: A LED lamp is designed so that it can be replaced by an ordinary person (as defined in
IEC 60050-826, 826.18.03).
– 10 – IEC 62504:2014 © IEC 2014
3.15.1
integrated LED lamp
LEDi lamp
LED lamp, incorporating controlgear, and any additional elements necessary for stable
operation of the light source, designed for direct connection to the supply voltage
3.15.2
non-integrated LED lamp
LEDni lamp
LED lamp which needs a separate controlgear to operate
3.15.3
retrofit LED lamp
LED lamp intended as a replacement of a non-LED lamp without requiring internal
modification of the luminaire
3.15.4
semi-integrated LED lamp
LEDsi lamp
LED lamp which carries the control unit of the controlgear, and is operated by the separated
power supply of the controlgear
3.16
LED light source
electrical light source based on LED technology
Note 1 to entry: A luminaire may include LED light sources but is not considered itself as a light source.
Note 2 to entry: LED light source(s) for a LED luminaire represents one or more LED lamp(s) or LED module(s).
3.17
LED luminaire
luminaire designed to incorporate one or more LED light source(s)
3.18
non-repairable, factory-sealed LED luminaire,
luminaire which cannot be dismantled without being permanently damaged, and incorporating
LED light source(s) and any additional elements necessary for starting and stable operation of
the light source
3.19 LED module
LED light source having no cap, incorporating one or more LED package(s) on a printed
circuit board, and possibly including one or more of the following: electrical, optical,
mechanical, and thermal components, interfaces and controlgear
Note 1 to entry: A LED module may be integrated (LEDi module, Type 1) or semi-integrated (LEDsi module,
Type 2) or non-integrated (LEDni module, Type 3).
Note 2 to entry: The LED module is usually designed to be part of a LED lamp or LED luminaire.
[SOURCE: IEC 62031, 3.2, modified – The definition is reworded and notes to entry are
added.]
3.19.1
built-in LED module
LED module, generally designed to form a replaceable part to be built into a luminaire, a box,
an enclosure or the like and not intended to be mounted outside a luminaire, etc. without
special precautions
[SOURCE: IEC 62031, 3.6, modified – The words ‘to be’ are added.]

3.19.2
independent LED module
LED module designed for mounting or placing separately from a luminaire, from an additional
box or enclosure or the like
Note 1 to entry: The independent LED module provides all the necessary protection with regard to safety
according to its classification and marking.
Note 2 to entry: An example of an independent LED module is a system where the LED module is connected via a
glass fibre with the luminaire head.
[SOURCE: IEC 62031, 3.8, modified – The second sentence in the definition as well as other
additional information are transferred into notes to entry replacing the original note.]
3.19.3
integral LED module
LED module, generally designed to form a non-replaceable part of a luminaire
[SOURCE: IEC 62031, 3.4]
3.19.4
integrated LED module
LEDi moduleLED module, incorporating controlgear and any additional elements necessary
for stable operation of the light source, designed for direct connection to the supply voltage
Note 1 to entry: LEDi modules are designated “Type 1”, see Annex A.
3.19.5
non-integrated LED module
LEDni module
LED module which needs a separate control circuitry or controlgear to operate
Note 1 to entry: LEDni modules are designated “Type 3”, see Annex A.
Note 2 to entry: One or more LED packages on a printed circuit board or substrate in a geometric structure are
regarded as a LED array. No further components are included like electrical, optical, mechanical, and thermal.
3.19.6
semi-integrated LED module
LEDsi module
LED module which carries the control unit of the controlgear, and is operated by the
separated power supply of the controlgear
Note 1 to entry: LED modules with control unit are designated “Type 2”, see Annex A.
3.20
LED package
single electrical component encapsulating principally one or more LED dies, possibly
including optical elements and thermal, mechanical, and electrical interfaces
Note 1 to entry: The component does not include the control unit of the controlgear, does not include a cap, and
is not connected directly to the supply voltage.
Note 2 to entry: A LED package is a discrete component and part of the LED module or LED lamp. For a
schematic built-up of a LED package, see Annex A.
3.21
luminous life time of LED package
L (t )
x j
time period at a specified junction temperature and forward current, determined by a minimum
level of x % of the measured initial luminous flux
Note 1 to entry: Luminous life time of LED package is expressed in hours (h).

– 12 – IEC 62504:2014 © IEC 2014
Note 2 to entry: t relates to LED die, but luminous life time of LED package are given with reference to t
j j
3.22
temperature
luminous life time of LED module related to t
p
L (t )
x p
time period at a specified performance temperature at which x % of the measured initial
luminous flux value is reached

Note 1 to entry: Luminous life time of LED module is expressed in hours (h).
Note 2 to entry: The use of forced cooling to achieve the specified t temperature should be stated.
p
3.23
light colour designation
three digit number, the first digit representing the first digit of the general colour rendering
index R [IEC 60050-845:1987, 845.02.63], and the second and third digit representing the
a
first two digits (thousands and hundreds) of the CCT of the light source
Note 1 to entry: The light colour designation is detailed in IEC TR 62732.
3.24
light emitting diode
LED
solid state device embodying a p-n junction, emitting incoherent optical radiation when excited
by an electric current
Note 1 to entry: This definition is independent from the existence of enclosure(s) and of terminals.
Note 2 to entry: The output is a function of its physical construction, material used and exciting current. The
optical emission may be in the ultraviolet, visible, or infrared wavelength regions.
Note 3 to entry: LED term normally represents the LED die (or chip), or LED package. It is also used as a generic
term representing the technology.
Note 4 to entry: LED term should not be used for reporting product performance (like luminous flux, colour
rendering, life time…) instead use for example “luminous flux of the LED module”
[SOURCE: IEC 60050-845:1987, 845.04.40, modified – The word 'incoherent' and the notes to
entry have been added and CIE S 017/E:2011 ILV, 17-662, modified.]
3.25
live part
conductive part which may cause an electric shock in normal use
Note 1 to entry: A process to align with IEC 61140 is underway and the definition will be designated by the term
“hazardous live part” in a future amendment.
3.26
luminous efficacy
η , η
V
quotient obtained when the emitted luminous flux is divided by the power consumed by the
source
–1
Note 1 to entry: Luminous efficacy is expressed in lm·W
Note 2 to entry: For LED applications, the source may be a LED package, module, lamp, luminaire etc.
[SOURCE: IEC 60050-845:1987, 845.01.55, modified – The words 'obtained when' and 'is
divided' and the notes to entry have been added and CIE S 017/E:2011 ILV, 17-730, modified]

3.27
luminous flux
Φ , Φ
V
quantity derived from radiant flux Φ by evaluating the radiation according to its action upon
e
the CIE standard photometric observer
Note 1 to entry: Luminous flux is expressed in lumen (lm).
Note 2 to entry: For photopic vision Φ = K ∫ (dΦ (λ )/dλ ) × V(λ )dλ where (dΦ (λ )/dλ) is the spectral
V m 360 e e
distribution of the radiant flux and V(λ ) is the spectral luminous efficiency.
Note 3 to entry: For the values of K (photopic vision) and K’ (scotopic vision), see IEC 60050-845, 845.01.56.
m m
Note 4 to entry: The luminous flux of LED dies is usually expressed in groups into which they are sorted.
[SOURCE: IEC 60050-845:1987, 845.01.25, modified – Second sentence become note 2 to
entry and note 4 to entry is added and CIE S 017/E:2011 ILV, 17-738, modified.]
3.28
luminous flux maintenance factor
lumen maintenance factor
ratio of the luminous flux emitted by the light source at a given time in its life to its initial
luminous flux emitted, the light source being operated under specified conditions
Note 1 to entry: This ratio is generally expressed in percent.
Note 2 to entry: The lumen maintenance factor of a LED light source is the effect of decrease of the luminous flux
output of the LED package or a combination of this with failure(s) of LED package if the LED light source contains
more than one LED package
[SOURCE: IEC 60050-845:1987, 845.07.65, modified – The words 'of a lamp' have been
replaced by 'emitted by the light source' and the notes to entry have been added and CIE S
017, 17-636, modified]
3.29
luminous intensity
I ; I
V
quotient of the luminous flux dΦ leaving the source and propagated in the element of solid
V
angle dΩ containing the given direction, by the element of solid angle
I = dΦ /dΩ
V V
–1
Note 1 to entry: Luminous intensity is expressed in candela, cd=lm·sr
Note 2 to entry: The definition holds strictly only for a point source.
Note 3 to entry: The luminous intensity of LED is reported according to CIE 127:2007 measurement procedure.
[SOURCE: IEC 60050-845:1987, 845.01.31 and CIE S 017/E:2011 ILV, 17-739, modified –
The notes to entry have been added.]
3.30
photometric code
under consideration
3.31
peak wavelength
λ
p
wavelength of radiation at the highest intensity of the spectral distribution
Note 1 to entry: Peak wavelength is expressed in nanometres (nm).

– 14 – IEC 62504:2014 © IEC 2014
[SOURCE: CIE 127, 7.2.1, modified – The definition has been simplified.]
3.32
rated life
length of time during which a population of LED light sources provides at least the claim for
maintained luminous flux percentage and at most the claim for failure fraction percentage F ,
y
as declared by the manufacturer or responsible vendor
Note 1 to entry: Rated life is expressed in hours (h).
3.33
rated value
value of a quantity used for specification purposes, established under standard test conditions
as declared by the manufacturer or responsible vendor
Note 1 to entry: The standard test conditions are given in the relevant standard.
[SOURCE: IEC 60050-151:2001, 151.16.08, modified – The text ‘for a specified set of
operating conditions of a component, device, equipment, or system’ has been replaced by
‘under standard test conditions as declared by the manufacturer or responsible vendor’ and
note 1 to entry has been added. ]
3.34
rated emergency lighting charging power
electrical power from the mains supply consumed by the charging circuit of emergency
luminaires
Note 1 to entry: Rated emergency lighting charging power is measured in Watts (W).
3.35
stabilisation time
time that is required for the LED light source or LED luminaire to obtain stable photometric
output and electrical power consumption with constant electrical input
3.36
standby power
electrical power consumed by the luminaire during the period when the light source(s) is(are)
not operating
Note 1 to entry: Standby power is expressed in Watts (W).
Note 2 to entry: For emergency lighting luminaires, this does not include the emergency lighting charging power.
3.37
supply voltage
voltage applied to the complete unit of LED light source or LED luminaire
[SOURCE: IEC 61347-1, 3.5, modified – The words 'circuit of lamp(s) and lamp controlgear'
have been replaced by 'unit of LED light source or LED luminaire'.]
3.38 temperature
3.38.1
ambient temperature
t
amb
temperature of air or another medium in the vicinity of the product under test
Note 1 to entry: Ambient temperature is expressed in degrees Celsius (°C).
Note 2 to entry: During the measurement of the ambient temperature, the measuring instrument/probe should be
shielded from draughts and radiant heating.

[SOURCE: IEC 60050-826, 826.10.03, modified – The word 'average' is omitted and the word
'equipment' is replaced by 'product under test' and 2.2.5 of CIE 127:2007.]
3.38.2
ambient performance temperature
ambient temperature related to the performance of the LED light source or LED luminaire
Note 1 to entry: Ambient performance temperature is expressed in degrees Celsius (°C).
3.38.3
board temperature
t
b
temperature of LED package or LED module between the printed circuit board and the thermal
interface
Note 1 to entry: Board temperature is expressed in degrees Celsius (°C).
3.38.4
heat transfer temperature
t
d
temperature occurring on a relevant part of the LED module (or any heat-conducting foil or
paste provided as for insertion if delivered with the LED module) (at the indicated position if
marked) which is intended for the passing of heat to the lampholder or to other parts of the
luminaire under normal operating conditions and at the rated voltage/current/power or the
maximum of the rated voltage/current/power range
Note 1 to entry: The temperature measured at the specified point gives information on the interface in which the
heat is to be transferred to the luminaire. An improper designed LED module does not pass the heat to the surface
where it should be transferred to the luminaire. As a result the t point will not stay below its maximum level and
c
the t point in the interface area remains cold.
d
Note 2 to entry: A measurement method is under consideration.
[SOURCE: IEC 62031, 3.11, modified – The word 'representative' is replaced by the word
'relevant' and the words 'provided' and 'which is' as well as the notes to entry have been
added'.]
3.38.5
junction temperature
t
j
temperature at the p-n junction
Note 1 to entry: Junction temperature is expressed in degrees Celsius (°C).
3.38.6
performance temperature
t
p
temperature related to performance of the LED module
Note 1 to entry: Performance temperature is expressed in degrees Celsius (°C).
Note 2 to entry: Temperature is measured at a given location t -point.
p
3.38.7
rated maximum performance ambient temperature
t
q,nn
highest ambient temperature around the luminaire related to a rated performance of the
luminaire under normal operating conditions, both as declared by the manufacturer or
responsible vendor
Note 1 to entry: Rated maximum performance ambient temperature is expressed in degrees Celsius (°C).

– 16 – IEC 62504:2014 © IEC 2014
Note 2 to entry: For a given life time, the t temperature is a fixed value, not a variable, where nn, the number
q,nn
in the suffix indicates the related lifetime claim in khours, example; t where nn = 60 represent 60 000 h lifetime
p,60
claim.
Note 3 to entry: There can be more than one t temperature, depending on the life time claim.
q,nn
3.38.8
rated maximum performance temperature
t
p,nn
highest temperature at t -point, related to a rated performance of the LED module, both as
p
declared by the manufacturer or responsible vendor

Note 1 to entry: Rated maximum performance temperature is expressed in degrees Celsius (°C).
Note 2 to entry: The location of t and t can be different.
p c
Note 3 to entry: For a given performance, the t temperature is a fixed value, not a variable, where nn, the
p,nn
number in the suffix indicates the related lifetime claim in khours, example; t where nn = 60 represent 60 000 h
p,60
lifetime claim.
Note 4 to entry: There can be more than one t , depending on the performance claim.
p,nn
3.38.9
rated maximum temperature
t
c
highest permissible safety related temperature which may occur on the outer surface of the
component (LED module or controlgear) (at the indicated position, if marked) under normal
operating conditions and at the rated voltage/current/power or the maximum of the rated
voltage/current/power range
Note 1 to entry: Rated maximum temperature is expressed in degrees Celsius (°C).
[SOURCE: IEC 61347-1, 3.16, modified and IEC 62031, 3.10, modified – Both definitions have
been combined]
3.38.10
storage temperature range
ambient temperature range within which a non-operated LED light source or LED luminaire
can be stored, when the claims of the specification are maintained
Note 1 to entry: Storage temperature range is expressed in degrees Celsius (°C).
3.38.11
temperature coefficient of the forward voltage
k
FV
change in forward voltage at a fixed current as a function of the junction temperature
–1
Note 1
...