IEC 60477-2:2022

Laboratory resistors - Part 2: Laboratory AC resistors

IEC 60477-2:2022 applies to resistors intended as laboratory AC resistors for use over a range of frequencies from DC up to a stated frequency which is not in excess of 1 MHz. Such resistors are hereinafter referred to as "AC resistors".
In addition to satisfying the requirements of IEC 60477-1, resistors satisfying the requirements of this document are designed to have a small variation of resistance and a small phase displacement over the stated frequency range.
IEC 60477-2:2022 cancels and replaces the first edition published in 1979, and Amendment 1:1997. This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous edition:
a) extended the AC resistor frequency range to 1 MHz;
b) updated the terms and definitions according to IEC 60050 series;
c) added the definition of AC/DC difference of an AC resistor;
d) added the resistor classification according to the AC resistance or AC/DC difference index;
e) updated the classification according to the AC resistor construction;
f) updated the safety symbols and requirements according to IEC 60477-1;
g) added the three-element equivalent circuits of an AC resistor in Annex C;
h) added the annex on constructions of AC resistors.

Résistances de laboratoire - Partie 2: Résistances de laboratoire à courant alternatif

L'IEC 60477-2:2022 s’applique aux résistances destinées à être utilisées comme résistances de laboratoire à courant alternatif dans un domaine de fréquences allant du courant continu jusqu’à une fréquence déclarée ne dépassant pas 1 MHz. Ces résistances sont, par la suite, désignées par l’expression "résistances à courant alternatif".
Les résistances qui, non seulement, satisfont aux exigences de l’IEC 60477-1, mais qui satisfont aussi aux exigences du présent document sont conçues de façon à avoir une variation de résistance faible et un déphasage faible dans le domaine de fréquences déclaré.
L'IEC 60477-2:2022 annule et remplace la première édition parue en 1979 et l’Amendement 1:1997. Cette édition constitue une révision technique.
Cette édition inclut les modifications techniques majeures suivantes par rapport à l’édition précédente:
a) extension du domaine de fréquences des résistances à courant alternatif à 1 MHz;
b) mise à jour des termes et définitions conformément à la série IEC 60050;
c) ajout de la définition de la différence entre le courant alternatif et le courant continu pour une résistance à courant alternatif;
d) ajout de la classification des résistances en fonction de la résistance en courant alternatif ou à l’indice de différence entre le courant alternatif et le courant continu;
e) mise à jour de la classification en fonction de la construction des résistances à courant alternatif;
f) mise à jour des symboles de sécurité et des exigences conformément à l’IEC 60477-1;
g) ajout des circuits équivalents à trois éléments d’une résistance à courant alternatif à l’Annexe C;
h) ajout de l’annexe relative aux constructions des résistances à courant alternatif.

General Information

• Status: Published
• Publication Date: 29-Mar-2022
• ICS: 17.220.20 - Measurement of electrical and magnetic quantities
• ICS: 31.040.01 - Resistors in general
• Technical Committee: TC 85 - Measuring equipment for electrical and electromagnetic quantities
• Drafting Committee: MT 25 - TC 85/MT 25
• Current Stage: PPUB - Publication issued
• Start Date: 22-Apr-2022
• Completion Date: 30-Mar-2022

Relations

• Revises: IEC 60477-2:1979/AMD1:1997 - Amendment 1 - Laboratory resistors. Part 2: Laboratory a.c. resistors
• Effective Date: 05-Sep-2023

Standards Content (Sample)

IEC 60477-2
®

Edition 2.0 2022-03
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE


Laboratory resistors –
Part 2: Laboratory AC resistors

Résistances de laboratoire –
Partie 2: Résistances de laboratoire à courant alternatif

IEC 60477-2:2022-03(en-fr)

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IEC 60477-2

®


Edition 2.0 2022-03




INTERNATIONAL



STANDARD




NORME


INTERNATIONALE











Laboratory resistors –

Part 2: Laboratory AC resistors



Résistances de laboratoire –

Partie 2: Résistances de laboratoire à courant alternatif
















INTERNATIONAL

ELECTROTECHNICAL

COMMISSION


COMMISSION

ELECTROTECHNIQUE


INTERNATIONALE




ICS 17.220.20; 31.040.01 ISBN 978-2-8322-1092-7




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

Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé.

® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale

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– 2 – IEC 60477-2:2022 © IEC 2022
CONTENTS
FOREWORD . 4
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 Resistor characterization and construction. 8
4.1 Resistor characterization . 8
4.2 Resistor construction . 9
5 General requirements . 9
5.1 DC resistance, AC resistance and time constant . 9
5.2 Multiple resistors . 10
5.3 Multi-dial resistors. 10
5.4 Connecting leads . 10
5.5 Conditions for the determination of DC and AC characteristics . 11
6 Permissible variations . 11
7 Further electrical and mechanical requirements . 12
8 Information, markings and symbols . 12
8.1 Information . 12
8.2 Markings and symbols . 12
Annex A (informative) Examples of markings . 14
A.1 Example of marking for a single AC resistor . 14
A.2 Example of marking for a five-dial AC resistor . 14
Annex B (informative) General considerations regarding laboratory AC resistors . 16
Annex C (informative) Equivalent circuits of an AC resistor . 18
C.1 General . 18
C.1.1 Two-element equivalent circuit of an AC resistor . 18
C.1.2 Three-element equivalent circuits . 20
C.2 Guard terminal . 23
Annex D (informative) Construction of AC resistors . 24
D.1 Construction and electrical definition of the impedance . 24
D.2 Two-terminal resistor . 24
D.3 Three-terminal resistor . 24
D.4 Four-terminal resistor . 25
D.5 Five-terminal resistor . 25
D.6 Four-terminal coaxial resistor . 26
D.7 Two-terminal-pair resistor . 26
D.8 Four-terminal-pair resistor . 27

Figure A.1 – Example of marking for a single AC resistor . 14
Figure A.2 – Example of marking for a five-dial resistor . 14
Figure C.1 – The three-element equivalent circuit of an AC resistor (Category A) . 20
Figure C.2 – The three-element equivalent circuit of an AC resistor (Category C) . 22
Figure D.1 – Two-terminal resistor . 24
Figure D.2 – Three-terminal resistor . 25
Figure D.3 – Four-terminal resistor . 25

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IEC 60477-2:2022 © IEC 2022 – 3 –
Figure D.4 – Five-terminal resistor . 26
Figure D.5 – Four-terminal coaxial resistor . 26
Figure D.6 – Two-terminal-pair resistor . 27
Figure D.7 – Four-terminal-pair resistor . 27

Table 1 – Limits of the AC resistance relative uncertainty . 9
Table 2 – Limits of the AC/DC difference . 10
Table 3 – Upper limit of the nominal range of use for frequency . 11

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– 4 – IEC 60477-2:2022 © IEC 2022
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________

LABORATORY RESISTORS –

Part 2: Laboratory AC resistors

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
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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.
IEC 60477-2 has been prepared by IEC technical committee 85: Measuring equipment for
electrical and electromagnetic quantities. It is an International Standard.
This second edition cancels and replaces the first edition published in 1979, and
Amendment 1:1997. This edition constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) extended the AC resistor frequency range to 1 MHz;
b) updated the terms and definitions according to IEC 60050 series;
c) added the definition of AC/DC difference of an AC resistor;
d) added the resistor classification according to the AC resistance or AC/DC difference index;
e) updated the classification according to the AC resistor construction;
f) updated the safety symbols and requirements according to IEC 60477-1;
g) added the three-element equivalent circuits of an AC resistor in Annex C;

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IEC 60477-2:2022 © IEC 2022 – 5 –
h) added the annex on constructions of AC resistors.
The text of this International Standard is based on the following documents:
Draft Report on voting
85/822/FDIS 85/825/RVD

Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.
A list of all parts in the IEC 60477 series, published under the general title Laboratory resistors,
can be found on the IEC website.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/standardsdev/publications.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under 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.

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– 6 – IEC 60477-2:2022 © IEC 2022
LABORATORY RESISTORS –

Part 2: Laboratory AC resistors



1 Scope
This part of IEC 60477 applies to resistors intended as laboratory AC resistors for use over a
range of frequencies from DC up to a stated frequency which is not in excess of 1 MHz. Such
resistors are hereinafter referred to as "AC resistors".
In addition to satisfying the requirements of IEC 60477-1, resistors satisfying the requirements
of this document are designed to have a small variation of resistance and a small phase
displacement over the stated frequency range.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies.
For undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC 60477-1, Laboratory resistors – Part 1: Laboratory DC resistors
3 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:
• ISO Online browsing platform: available at http://www.iso.org/obp
• IEC Electropedia: available at http://www.electropedia.org/
3.1
equivalent electric circuit
circuit composed of ideal circuit elements which has, at the terminals or ports, a behaviour
equivalent to that of a given electric or magnetic circuit or device
Note 1 to entry: Equivalent electric circuits can also be used to represent other kinds of devices or phenomena.
[SOURCE: IEC 60050-131:2002, 131-15-07]
3.2
circuit element
in electromagnetism, mathematical model of a device characterized by one or more relations
between integral quantities
[SOURCE: IEC 60050-131:2002, 131-11-03]

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IEC 60477-2:2022 © IEC 2022 – 7 –
3.3
equivalent circuit of an AC resistor
equivalent electric circuit of an AC resistor
electric circuit which has the same AC characteristics as a resistor, and which would have an
impedance equal to the resistor under specified operating conditions
Note 1 to entry: Specified operating conditions should include working frequency and voltage.
3.4
two-element equivalent circuit of an AC resistor
equivalent circuit of an AC resistor with two elements under specified operating conditions
Note 1 to entry: A two-element equivalent circuit of an AC resistor is given by either an equivalent AC resistance,
R in series with an equivalent inductance, L or an equivalent AC resistance, R in parallel with an equivalent
s s p
capacitance, C (see Annex C).
p
3.5
three-element equivalent circuit of an AC resistor
equivalent electric circuit of an AC resistor with three elements under specified operating
conditions
3.6
equivalent AC resistance of an AC resistor
AC resistance
or R ) which is the AC resistive component of the resistor
value of resistance (R
s p
Note 1 to entry: The AC resistance is usually taken as the equivalent series resistance R , for resistors of
s
, for resistors of Category C (see Annex B).
Category A, and as the equivalent parallel resistance R
p
3.7
terminal pair
port consisting of two terminals such that the electric current directed from an external circuit
or device to one terminal is identical with the current directed from the other terminal to the
external circuit or device
[SOURCE: IEC 60050-131:2002, 131-12-63]
3.8
time constant
τ
-t/τ
time τ in the expression F(t) = A + Be of a quantity F growing or decaying exponentially
-t/τ
towards a constant value A with increasing time t, or in the expression F(t) = A + f(t)e of an
exponentially damped oscillation, where f is a periodic function of time
Note 1 to entry: The time constant of an exponentially varying quantity is the duration of a time interval at the end
of which the absolute value of the difference between the quantity and the limit has decreased to 1/e of the absolute
value of this difference at the beginning of the time interval, where e is the base of natural logarithms.
Note 2 to entry: For a resistor, at any particular frequency, the time constant is defined as either: L /R , or R C
s s p p
whichever yields a positive value (see Annex C). For determining the time constant, the DC resistance may be used
instead of the equivalent AC resistance.
Note 3 to entry: For a resistor using the three-element equivalent circuit expressed, the time constant is
L L
approximately equal to: − CR , or CR− (see Annex C).
R R

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– 8 – IEC 60477-2:2022 © IEC 2022
Note 4 to entry: The phase displacement of the current flowing through the resistor from the voltage appearing
L
across it with a time constant L /R or − CR is such that the current is lagging, and that with a time constant R C
s s p p
R
L
or CR− is leading when L and C , have positive values, L and L being expressed in henrys, R , R and R in ohms
s p s s p
R
and C and C in farads.
p
[SOURCE: IEC 60050-103:2009, 103-05-26, modified – The existing Note 2 has been deleted
and a new Note 2, Note 3 and Note 4 to entry have been added to adapt to usage in AC resistor
technology.]
3.9
time constant index
conventional designation of a time constant by a number or symbol
Note 1 to entry: In this document, the time constant index is expressed in seconds using the appropriate SI prefix.
3.10
AC/DC difference
difference between the equivalent AC resistance at a stated frequency and
the DC resistance, expressed as a percentage (%) of the DC resistance
3.11
AC/DC difference index
number which designates the limit of the AC/DC difference in nominal range of use for
frequency, expressed in %
3.12
frequency index
number which designates the upper limit of the nominal range of use for frequency, expressed
in hertz using the appropriate SI prefix
3.13
skin effect
for an alternating electric current in a conductor, phenomenon in which the current density is
greater near the surface than in the interior of the conductor
Note 1 to entry: The skin effect increases the resistance and decreases the inductance of a conductor with the
frequency of the electric current.
Note 2 to entry: The skin effect occurs also in the more general case of any time-varying current.
[SOURCE: IEC 60050-121:1998, 121-13-18]
3.14
residual inductance
inductance value between the points of connection of a multiple or multi-dial AC resistor having
switching devices with a zero position, when all switching elements are set to the zero position
4 Resistor characterization and construction
4.1 Resistor characterization
AC resistors satisfying the requirements of this document are characterized:
a) by classes related to their DC accuracy as specified in IEC 60477-1,
b) by classes related to their equivalent AC resistance as specified in 5.1 or AC/DC difference
indices as specified in 5.1, and
c) by time constant indices as specified in 5.1, and

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IEC 60477-2:2022 © IEC 2022 – 9 –
d) by frequency indices as specified in Clause 6.
4.2 Resistor construction
Because of the uncertainties in AC properties which can result from stray inductances, stray
capacitances, eddy currents, dielectric absorption effects and skin effects, the AC resistors to
which this document applies are classified according to their construction (see Annex D), as
follows:
a) two-terminal resistor, each terminal being able to be used both for current or potential;
b) three-terminal resistor which has one more shield terminal (can also be called a guard
terminal) connected to the electric screen than the two-terminal resistor to reduce the stray
capacitances effect;
c) four-terminal resistor which has independent current terminals and potential terminals to
reduce the stray inductances and contact resistances;
d) five-terminal resistor which has one more shield terminal than the four-terminal resistor;
e) four-terminal coaxial resistor which has two terminal-pairs with the outer shield conductors
working as the low terminal of current or potential;
f) two-terminal-pair resistor which has two terminal-pairs with the outer shield conductors
working as the return path for the signal current (not grounded);
g) four-terminal-pair resistor which has four terminal-pairs with the outer shield conductors
working as the return path for the signal current (not grounded) to eliminate the effect of
mutual coupling between the current and potential leads.
5 General requirements
5.1 DC resistance, AC resistance and time constant
The DC characteristics of an AC resistor shall be as specified in IEC 60477-1.
The equivalent AC resistance of an AC resistor characterized by class related to the AC
resistance shall comply with the limits of relative uncertainty as specified for their AC resistance
class index in Table 1 at initial calibration.
Table 1 – Limits of the AC resistance relative uncertainty
AC resistance
0,000 01 0,000 02 0,000 05 … 2 5 10
class index
Limits of relative
uncertainty for 0,000 01 % 0,000 02 % 0,000 05 % … 2 % 5 % 10 %
AC resistance
NOTE The value of the AC resistance of a given resistor is somewhat dependent on the frequency at which it is
measured. However, as the purpose here is to classify AC resistors, measurements at 1 kHz (or lower) are
generally adequate.

The AC/DC difference of an AC resistor characterized by AC/DC difference index shall comply
with the limits of AC/DC difference specified for its AC/DC difference index in Table 2 at initial
calibration.

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– 10 – IEC 60477-2:2022 © IEC 2022
Table 2 – Limits of the AC/DC difference
AC/DC
0,000 001 0,000 002 0,000 005 … 0,2 0,5 1
difference index
Limits of the
AC/DC ±0,000 001 % ±0,000 002 % ±0,000 005 % … ±0,2 % ±0,5 % ±1 %
difference
NOTE Measurements at 1 kHz (or lower) are here generally adequate.

An AC resistor shall choose either an AC resistance class index or an AC/DC difference index
to show the AC resistance character.
The time constant of an AC resistor shall not exceed the appropriate value of the time constant
index selected from the sequence:
• 1 ns, 2 ns, 5 ns, 10 ns, …100 μs.
NOTE The value of the time constant of a given resistor is also somewhat dependent on the frequency at which it
is measured. Measurements at 1 kHz (or lower) are here generally adequate as with the measurements of AC
resistance.
5.2 Multiple resistors
Multiple resistors, excluding multi-dial resistors, may have a different AC resistance class or
AC/DC difference and time constant index for each selectable value.
For a multiple resistor in which the lowest selectable resistance value is nominally zero, the
manufacturer shall state the value of the residual inductance under this condition.
5.3 Multi-dial resistors
Multi-dial resistors shall have a single AC resistance class index or AC/DC difference index and
a single time constant index for all selectable values on any dial used alone. The several dials
may each have a different AC resistance class index or AC/DC difference index and a different
time constant index.
The AC resistance class index or AC/DC difference index of a given dial shall also apply at any
setting of the dial when that dial is used in conjunction with any setting of any dial(s) inferior to
it in value.
The time constant index of a given dial shall also apply at any setting of the dial when that dial
is used in conjunction with any setting of any dial(s) inferior to it in value.
5.4 Connecting leads
Separate current and potential connections shall be made to a resistor having a pair of terminals
for each port of connection, unless other conditions are stated by the manufacturer. The mutual
inductances between the current and potential leads and between each of these leads and the
resistor shall be minimized.
The leads making connection
...