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
Current Stage
PPUB - Publication issued
Completion Date
30-Mar-2022
Ref Project

Buy Standard

Standard
IEC 60477-2:2022 - Laboratory resistors - Part 2: Laboratory AC resistors
English and French language
54 pages
sale 15% off
Preview
sale 15% off
Preview

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)
---------------------- Page: 1 ----------------------
THIS PUBLICATION IS COPYRIGHT PROTECTED
Copyright © 2022 IEC, Geneva, Switzerland

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form

or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from

either IEC or IEC's member National Committee in the country of the requester. If you have any questions about IEC

copyright or have an enquiry about obtaining additional rights to this publication, please contact the address below or

your local IEC member National Committee for further information.

Droits de reproduction réservés. Sauf indication contraire, aucune partie de cette publication ne peut être reproduite

ni utilisée sous quelque forme que ce soit et par aucun procédé, électronique ou mécanique, y compris la photocopie

et les microfilms, sans l'accord écrit de l'IEC ou du Comité national de l'IEC du pays du demandeur. Si vous avez des

questions sur le copyright de l'IEC ou si vous désirez obtenir des droits supplémentaires sur cette publication, utilisez

les coordonnées ci-après ou contactez le Comité national de l'IEC de votre pays de résidence.

IEC Secretariat Tel.: +41 22 919 02 11
3, rue de Varembé info@iec.ch
CH-1211 Geneva 20 www.iec.ch
Switzerland
About the IEC

The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes

International Standards for all electrical, electronic and related technologies.
About IEC publications

The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the

latest edition, a corrigendum or an amendment might have been published.

IEC publications search - webstore.iec.ch/advsearchform IEC Products & Services Portal - products.iec.ch

The advanced search enables to find IEC publications by a Discover our powerful search engine and read freely all the

variety of criteria (reference number, text, technical publications previews. With a subscription you will always

committee, …). It also gives information on projects, replaced have access to up to date content tailored to your needs.

and withdrawn publications.
Electropedia - www.electropedia.org
IEC Just Published - webstore.iec.ch/justpublished
The world's leading online dictionary on electrotechnology,
Stay up to date on all new IEC publications. Just Published
containing more than 22 300 terminological entries in English
details all new publications released. Available online and
and French, with equivalent terms in 19 additional languages.
once a month by email.
Also known as the International Electrotechnical Vocabulary
(IEV) online.
IEC Customer Service Centre - webstore.iec.ch/csc
If you wish to give us your feedback on this publication or
need further assistance, please contact the Customer Service
Centre: sales@iec.ch.
A propos de l'IEC

La Commission Electrotechnique Internationale (IEC) est la première organisation mondiale qui élabore et publie des

Normes internationales pour tout ce qui a trait à l'électricité, à l'électronique et aux technologies apparentées.

A propos des publications IEC

Le contenu technique des publications IEC est constamment revu. Veuillez vous assurer que vous possédez l’édition la

plus récente, un corrigendum ou amendement peut avoir été publié.
Recherche de publications IEC - IEC Products & Services Portal - products.iec.ch

webstore.iec.ch/advsearchform Découvrez notre puissant moteur de recherche et consultez

La recherche avancée permet de trouver des publications IEC gratuitement tous les aperçus des publications. Avec un

en utilisant différents critères (numéro de référence, texte, abonnement, vous aurez toujours accès à un contenu à jour

comité d’études, …). Elle donne aussi des informations sur adapté à vos besoins.
les projets et les publications remplacées ou retirées.
Electropedia - www.electropedia.org
IEC Just Published - webstore.iec.ch/justpublished
Le premier dictionnaire d'électrotechnologie en ligne au
Restez informé sur les nouvelles publications IEC. Just
monde, avec plus de 22 300 articles terminologiques en
Published détaille les nouvelles publications parues.
anglais et en français, ainsi que les termes équivalents dans
Disponible en ligne et une fois par mois par email.
19 langues additionnelles. Egalement appelé Vocabulaire
Electrotechnique International (IEV) en ligne.
Service Clients - webstore.iec.ch/csc
Si vous désirez nous donner des commentaires sur cette
publication ou si vous avez des questions contactez-nous:
sales@iec.ch.
---------------------- Page: 2 ----------------------
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
---------------------- Page: 3 ----------------------
– 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

---------------------- Page: 4 ----------------------
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

---------------------- Page: 5 ----------------------
– 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

co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and

in addition to other activities, IEC publishes International Standards, Technical Specifications, Technical Reports,

Publicly Available Specifications (PAS) and Guides (hereafter referred to as "IEC Publication(s)"). Their

preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with

may participate in this preparatory work. International, governmental and non-governmental organizations liaising

with the IEC also participate in this preparation. IEC collaborates closely with the International Organization for

Standardization (ISO) in accordance with conditions determined by agreement between the two organizations.

2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international

consensus of opinion on the relevant subjects since each technical committee has representation from all

interested IEC National Committees.

3) IEC Publications have the form of recommendations for international use and are accepted by IEC National

Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC

Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any

misinterpretation by any end user.

4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications

transparently to the maximum extent possible in their national and regional publications. Any divergence between

any IEC Publication and the corresponding national or regional publication shall be clearly indicated in the latter.

5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity

assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any

services carried out by independent certification bodies.

6) All users should ensure that they have the latest edition of this publication.

7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and

members of its technical committees and IEC National Committees for any personal injury, property damage or

other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and

expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC

Publications.

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;
---------------------- Page: 6 ----------------------
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.
---------------------- Page: 7 ----------------------
– 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]
---------------------- Page: 8 ----------------------
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).
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

, for resistors of Category C (see Annex B).
Category A, and as the equivalent parallel resistance R
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
-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
---------------------- Page: 9 ----------------------
– 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

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

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
and C and C in farads.

[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
---------------------- Page: 10 ----------------------
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.
---------------------- Page: 11 ----------------------
– 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
...

Questions, Comments and Discussion

Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.