EN 60477-2:1997
(Main)Laboratory resistors - Part 2: Laboratory a.c. resistors
Laboratory resistors - Part 2: Laboratory a.c. resistors
In addition to above, applicable up to 100 kHz. Resistor characterization.
Meßwiderstände - Teil 2: Wechselstrom-Meßwiderstände
Résistances de laboratoire - Partie 2: Résistances de laboratoire à courant alternatif
Mêmes prescriptions que ci-dessus applicables jusqu'à 100 kHz; en outre, caractérisation d'une résistance.
Laboratorijski upori – 2. del: Laboratorijski upori za izmenični tok (IEC 60477-2:1979)
General Information
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Standards Content (Sample)
SLOVENSKI STANDARD
01-september-2000
/DERUDWRULMVNLXSRUL±GHO /DERUDWRULMVNLXSRUL]DL]PHQLþQLWRN ,(&
Laboratory resistors -- Part 2: Laboratory a.c. resistors
Meßwiderstände -- Teil 2: Wechselstrom-Meßwiderstände
Résistances de laboratoire -- Partie 2: Résistances de laboratoire à courant alternatif
Ta slovenski standard je istoveten z: EN 60477-2:1997
ICS:
17.220.20 0HUMHQMHHOHNWULþQLKLQ Measurement of electrical
PDJQHWQLKYHOLþLQ and magnetic quantities
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
NORME CEI
INTERNATIONALE
IEC
477-2
INTERNATIONAL
Première édition
STANDARD
First edition
Résistances de laboratoire
Deuxième partie:
à courant alternatif
Résistances de laboratoire
Laboratory resistors
Part 2:
Laboratory a.c. resistors
© CEI 1979 Droits de reproduction réservés — Copyright - all rights reserved
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— 3 —
CONTENTS
Page
FOREWORD 5
PREFACE 5
Clause
1. Scope 7
2. Definitions 7
3. Resistor characterization
4. General requirements
5. Permissible variations 13
mechanical requirements 15
6. Further electrical and
7. Markings and symbols
APPENDIX A — Examples of markings 19
APPENDIX B — General considerations regarding laboratory a. c. resistors
APPENDIX C — Equivalent circuits of an a. c. resistor 27
– 5 --
INTERNATIONAL ELECTROTECHNICAL COMMISSION
LABORATORY RESISTORS
Part 2: Laboratory a. c. resistors
FOREWORD
The formal decisions or agreements of the IEC on technical matters, prepared by Technical Committees on which all the
1)
National Committees having a special interest therein are represented, express, as nearly as possible, an international consensus
of opinion on the subjects dealt with.
2) They have the form of recommendations for international use and they are accepted by the National Committees in that sense.
In order to promote international unification, the I E C expresses the wish that all National Committees should adopt the text of
3)
the IEC recommendation for their national rules in so far as national conditions will permit. Any divergence between the 1E
recommendation and the corresponding national rules should, as far as possible, be clearly indicated in the latter.
PREFACE
This standard has been prepared by Sub-Committee 13B, Electrical Measuring Instruments, of IE
Technical Committee No. 13, Electrical Measuring Equipment.
It forms Part 2 of 1E Publication 477 which, after revision, will be issued as Publication 477-1.
Drafts were discussed at the meetings held in The Hague in 1975 and in Warsaw in 1976. As a result of
this latter meeting, a draft, Document 13B(Central Office)54, and a corrigendum to it, Document
13B(Central Office)54A, were submitted to the National Committees for approval under the Six Months'
Rule in November 1976 and in April 1977 respectively. Though the Six Months' Rule document together
with the corrigendum were approved by the National Committees, further modifications became neces-
sary. Therefore, these amendments, Document 13B(Central Office)63, were submitted to the National
Committees for approval under the Two Months' Procedure in July 1978.
The National Committees of the following countries voted explicitly in favour of publication:
Argentina Hungary
Italy
Australia
Japan
Austria
Poland
Belgium
Romania
Brazil
South Africa (Republic of)
Canada
China Sweden
Switzerland
Denmark
Turkey
Egypt
United Kingdom
Finland
United States of America
France
Germany
Other IEC publication quoted in this standard:
Publication No. 477: Laboratory D.C. Resistors (quoted in Sub-clauses 1.2, 2.6, 3.1, 4.1.1, 4.5.1, 4.5.2, Clause 5, Sub-clauses
5.1, 6.1, 7.3, 7.4, Appendix A: Clauses AI and A2 and Appendix B of this standard).
– 7 –
LABORATORY RESISTORS
Part 2: Laboratory a. c. resistors
1. Scope
1.1 This standard applies to resistors intended as laboratory a. c. resistors for use over a range of fre-
quencies from d. c. up to a stated frequency which is not in excess of 100 kHz. Such resistors are
hereinafter referred to as "a.c. resistors".
1.2 In addition to satisfying the requirements of I E C Publication 477, resistors satisfying the require-
ments of this standard are designed to have a small variation of resistance and a small phase dis-
placement over the stated frequency range.
1.3 Because of the uncertainties in a. c. properties which can result from stray inductances, stray capaci-
tances, eddy currents and dielectric absorption effects, the a. c. resistors to which this standard
applies are classified according to their construction, as follows:
1.3.1 According to the number of main terminals, into one of the following types:
a) Resistors having a pair of terminals at each point of connection.
b) Resistors having a single terminal at each point of connection.
1.3.2 According to the method of protection against externally produced electric fields, into one of the
following types:
a) Resistors not having an electric screen*.
b) Resistors having an electric screen which is permanently connected to one of the points of con-
nection.
c) Resistors having an electric screen which is not connected to the terminals of the resistor but
which is provided with a separate terminal, sometimes called the "guard terminal".
1.4 In this standard, a. c. voltages and currents are assumed to have a substantially sinusoidal wave-
form.
Note. – For general information about a.c. resistors, see Appendices B and C.
2. Definitions
For the purposes of this standard, the following definitions apply:
2.1 Representation of the a. c. properties of a resistor
The a. c. characteristics of a resistor are given by:
* The a. c. properties of an unscreened resistor are dependent on the stray capacitances which exist, in effect, across the
resistor. Testing conditions can thus considerably affect the a.c. properties. Sub-clause 4.5.6 therefore lays down the testing
conditions concerning electric screening.
– 9 –
2.1.1 either an equivalent a. c. resistance, R, in series with an equivalent inductance, L S, or
2.1.2 an equivalent a. c. resistance, R p, in parallel with an equivalent capacitance, Cp.
2.2 Equivalent a. c. resistance
(R s which is the a. c. resistive component of the resistor (see Sub-
The value of resistance or R p)
clause 2.1).
2.3 Time constant
The time constant is denoted by r * ; it is defined as either:
2.3.1 L s/ R„ or
2.3.2 Rp Cp, whichever yields a positive value (see Appendix C).
Notes 1. – The unit for time constant is the second, L s being expressed in henrys, RS and R p in ohms and Cp in farads.
2. – For determining the time constant, the d.c. resistance may be used instead of the equivalent a.c. resistance.
3. – The phase displacement of the current flowing through the resistor from the voltage appearing across it with a
time constant L s/R S is such that the current is lagging, and that with a time constant R p Cp is leading when L S and
Cp have positive values.
For those cases where the simple representation would lead to an apparently negative time constant (see Clause
4.–
C2 of Appendix C), the time constant is not used and the reactive component is stated instead.
2.4 Time constant index
The number which designates the permissible upper limit of the time constant of a group of
resistors, all of which can be designated by the same number if they comply with all the require-
ments of this standard concerning time constant. It is expressed in seconds using the appropriate
SI prefix.
2.5 Variation due to frequency
The difference between the equivalent a. c. resistance at a stated frequency and the d. c. resist-
ance. It is expressed in percentage (%) or in parts per million (ppm) of the d. c. resistance.
2.6 Upper limit of the nominal range of use for frequency
The specified frequency up to which the variation due to frequency does not exceed the permiss-
ible intrinsic d. c. resistance error corresponding to the (d. c.) resistance class index (see I E C Publi-
cation 477).
2.7 Frequency index
The number which designates the upper limit of the nominal range of use for frequency,
expressed in kilohertz (see Table I).
* Lower-case Greek tau.
– 1 1 –
3. Resistor characterization
A.C. resistors satisfying this standard are characterized:
3.1 by classes related to their d.c. accuracy as specified in I E C Publication 477,
3.2 by time constant indices as specified in Sub-clause 4.1.2 and
3.3 by frequency indices as specified in Sub-clause 5.2.
4. General requirements
4.1 D. C. resistance, a. c. resistance and time constant
4.1.1 The d.c. characteristics of an a. c. resistor shall be as specified in I E C Publication 477.
Note. – The a.c. resistance is usually taken as the equivalent series resistance
R,, for resistors up to 100 S2, and as the equiv-
alent parallel resistance R, for resistors above 100 S2.
4.1.2 The time constant at the points of connection of an a. c. resistor shall not exceed the appropriate
value of the time constant index selected from the sequence:
1 ns, 2 ns, 5 ns, 10 ns, ., 100µs.
Note. –
The value of the time constant of a given resistor is somewhat dependent on the frequency at which it is measured.
However, as the purpose here is to effect a classification of resistors, not to provide an exact value of time constant,
measurements at 1 kHz (or lower) are here generally adequate.
4.2 Multiple resistors
4.2.1 Multiple resistors, excluding multi-decade resistors, ma y have a different time constant index for
each selectable value.
4.2.2 For a multiple resistor in which the lowest selectable resistance value is nominally zero, the manu-
facturer shall state the value of the residual inductance under this condition.
4.3 Multi-decade resistors
Multi-decade resistors shall have a single time constant index for all selectable values on any
decade used alone. The several decades may each have a different time constant index.
The time constant index of a given decade shall also apply at any setting of the decade when that
decade is used in conjunction with any setting of any decade(s) inferior to it in value.
4.4 Connecting leads
4.4.1 Separate current and potential connections shall be made to a resistor having a pair of terminals
for each point 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 re-
sistor shall be minimized.
– 13 –
4.4.2 The leads making connection to a resistor having a single terminal for each point of connection
shall be arranged so as to minimize their inductance.
Note. — This is particularly important for resistors of values of 10 S2 and lower.
4.4.3 The leads making connection to a resistor shall not alter significantly the equivalent parallel
capacitance, if necessary by the provision of an electrostatic screen for each lead and by the use of
an appropriate measuring circuit.
Note. —The magnitude of capacitance that will cause a significant alteration will depend upon the value of the resistance
and the time constant.
4.5 Conditions for the determination of d. c. and a. c. characteristics
4.5.1 All tests of d.c. characteristics shall be carried out as specified in I EC Publication 477.
Note.— At low frequencies, the error of an a. c. resistor is essentially the same as its error at d.c.
At higher frequencies, an additional variation as specified by Sub-clause 5.1 is permitted.
4.5.2 All tests of a. c. characteristics shall be carried out under the reference conditions specified in I E C
Publication 477.
4.5.3 The time constant of an a. c. resistor shall be measured at a frequency of 1 kHz or at the frequency
corresponding to its frequency index if the latter is lower (see Clause 5).
4.5.4 The residual inductance of an a. c. resistor (see Sub-clause 4.2.2) shall be measured with the re-
sistor connected as in normal use and at a frequency of 1 kHz or at the frequency corresponding to
its frequency index if the latter is lower (see Clause 5).
4.5.5 A resistor having an electric screen (see Items b) and c) of Sub-clause 1.3.2) shall be tested with the
screen connected as specified by the manufacturer.
4.5.6 A resistor not having an electric screen (see Item a) of Sub-clause 1.3.2) shall be tested within an
earthed conductive enclosure as specified by the manufacturer. If this enclosure is not specified, the
resistor shall be tested within an earthed conductive enclosure separated from the surface of the
resistor by between 10 mm and 20 mm at all places.
4.5.7 Any other necessary conditions shall be stated by the manufacturer.
4.5.8 When necessary, details of the testing method shall be agreed between the manufacturer and the
user.
5. Permissible variations
Changes in influence quantities over the nominal ranges of use specified in I EC Publication 477
will cause no significant effect on the a. c. characteristics of the resistor. Requirements relating to
variations of a. c. characteristics other than those due to frequency are therefore not included in this
standard.
– 15 –
5.1 When the a. c. resistor is under reference conditions as specified in I EC P
...
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