prEN IEC 60477-2:2021

Laboratory resistors - Part 2: Laboratory AC resistors

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, resistors satisfying the requirements of this standard are designed to have a small variation of resistance and a small phase displacement over the stated frequency range. Because of the uncertainties in AC properties which can result from stray inductances, stray capacitances, eddy currents, dielectric absorption effects and skin effect, the AC resistors to which this standard applies are classified according to their construction (see Annex D), as follows: a) Two-terminal resistor which each of one terminal both for current and potential; b) Three-terminal resistor which has one more shield terminal (also could be called as 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.

Labor-Widerstände - Teil 2: Labor-Wechselstromwiderstände

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

Laboratorijski upori - 2. del: Laboratorijski upori za izmenični tok

General Information

• Status: Not Published
• ICS: 17.220.20 - Measurement of electrical and magnetic quantities
• ICS: 31.040.01 - Resistors in general
• Technical Committee: CLC/TC 85X - Measuring equipment for electrical and electromagnetic quantities
• Drafting Committee: IEC/TC 85 - IEC_TC_85
• Current Stage: 4020 - Enquiry circulated
• Due Date: 21-May-2021
• Completion Date: 21-May-2021
• Directive: 2014/35/EU - Directive 2014/35/EU of the European Parliament and of the Council of 26 February 2014 on the harmonisation of the laws of the Member States relating to the making available on the market of electrical equipment designed for use within certain voltage limits
• Mandate: M/511 - Mandate to CEN, CENELEC and ETSI relating to harmonised standards in the field of the Low Voltage Directive
• Ref Project: oSIST prEN IEC 60477-2:2021 - Laboratory resistors. Part 2: Laboratory AC resistors

RELATIONS

• Revised: EN 60477-2:1997 - Laboratory resistors - Part 2: Laboratory a.c. resistors
• Effective Date: 10-Nov-2020
• Revised: EN 60477-2:1997/A1:1997 - Laboratory resistors - Part 2: Laboratory a.c. resistors
• Effective Date: 12-Oct-2021

Standards Content (sample)

SLOVENSKI STANDARD
oSIST prEN IEC 60477-2:2021
01-julij-2021
Laboratorijski upori - 2. del: Laboratorijski upori za izmenični tok
Laboratory resistors. Part 2: Laboratory AC resistors

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

Ta slovenski standard je istoveten z: prEN IEC 60477-2:2021
ICS:
17.220.20 Merjenje električnih in Measurement of electrical
magnetnih veličin and magnetic quantities
oSIST prEN IEC 60477-2:2021 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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oSIST prEN IEC 60477-2:2021
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oSIST prEN IEC 60477-2:2021
85/772/CDV
COMMITTEE DRAFT FOR VOTE (CDV)
PROJECT NUMBER:
IEC 60477-2 ED2
DATE OF CIRCULATION: CLOSING DATE FOR VOTING:
2021-05-21 2021-08-13
SUPERSEDES DOCUMENTS:
85/735/CD, 85/758/CC
IEC TC 85 : MEASURING EQUIPMENT FOR ELECTRICAL AND ELECTROMAGNETIC QUANTITIES
SECRETARIAT: SECRETARY:
China Ms Guiju HAN
OF INTEREST TO THE FOLLOWING COMMITTEES: PROPOSED HORIZONTAL STANDARD:
Other TC/SCs are requested to indicate their interest, if
any, in this CDV to the secretary.
FUNCTIONS CONCERNED:
EMC ENVIRONMENT QUALITY ASSURANCE SAFETY

SUBMITTED FOR CENELEC PARALLEL VOTING NOT SUBMITTED FOR CENELEC PARALLEL VOTING

Attention IEC-CENELEC parallel voting
The attention of IEC National Committees, members of
CENELEC, is drawn to the fact that this Committee Draft
for Vote (CDV) is submitted for parallel voting.
The CENELEC members are invited to vote through the
CENELEC online voting system.

This document is still under study and subject to change. It should not be used for reference purposes.

Recipients of this document are invited to submit, with their comments, notification of any relevant patent rights of

which they are aware and to provide supporting documentation.
TITLE:
Laboratory resistors. Part 2: Laboratory AC resistors
PROPOSED STABILITY DATE: 2025
NOTE FROM TC/SC OFFICERS:

Copyright © 2021 International Electrotechnical Commission, IEC. All rights reserved. It is permitted to download this

electronic file, to make a copy and to print out the content for the sole purpose of preparing National Committee positions.

You may not copy or "mirror" the file or printed version of the document, or any part of it, for any other purpose without

permission in writing from IEC.
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2 CONTENTS

3 FOREWORD ...................................................................................................................... - 3 -

4 1 Scope ......................................................................................................................... - 5 -

5 2 Normative references ................................................................................................. - 5 -

6 3 Terms and definitions ................................................................................................. - 5 -

7 4 Resistor characterization ............................................................................................ - 7 -

8 5 General requirements ................................................................................................. - 7 -

9 5.1 DC resistance, AC resistance and time constant ................................................ - 7 -

10 5.2 Multiple resistors................................................................................................ - 8 -

11 5.3 Multi-dial resistors ............................................................................................. - 8 -

12 5.4 Connecting leads ............................................................................................... - 8 -

13 5.5 Conditions for the determination of DC and AC characteristics ........................... - 9 -

14 6 Permissible variations................................................................................................. - 9 -

15 7 Further electrical and mechanical requirements ........................................................ - 10 -

16 8 Information, markings and symbols ........................................................................... - 10 -

17 8.1 Information ...................................................................................................... - 10 -

18 8.2 Markings and symbols ..................................................................................... - 10 -

19 Annex A (informative) Examples of markings ................................................................. - 11 -

20 A.1 Example of marking for a single resistor .......................................................... - 11 -

21 A.2 Example of marking for a five-dial resistor ....................................................... - 11 -

22 Annex B (informative) General considerations regarding laboratory AC resistors ........... - 13 -

23 Annex C (informative) Equivalent circuits of an AC resistor ............................................ - 14 -

24 Annex D (informative) Construction of AC resistors ........................................................ - 18 -

25 D.1 Construction and electrical definition of the impedance .................................... - 18 -

26 D.2 Two-terminal resistor ....................................................................................... - 18 -

27 D.3 Three-terminal resistor ..................................................................................... - 18 -

28 D.4 Four-terminal resistor ....................................................................................... - 19 -

29 D.5 Five-terminal resistor ....................................................................................... - 19 -

30 D.6 Four-terminal coaxial resistor ........................................................................... - 19 -

31 D.7 Two-terminal-pair resistor ................................................................................ - 20 -

32 D.8 Four-terminal-pair resistor................................................................................ - 20 -

34 Figure A.1 –Example of marking for a single AC resistor .................................................. - 11 -

35 Figure A.2 –Example of marking for a five-dial resistor .................................................... - 11 -

36 Figure C.1 –The three-element equivalent circuit of AC resistor (Category A) .................. - 15 -

37 Figure C.2 –The three-element equivalent circuit of AC resistor (Category C) .................. - 16 -

38 Figure D.1 – Two-terminal resistor ................................................................................... - 18 -

39 Figure D.2 – Three-terminal resistor ................................................................................ - 18 -

40 Figure D.3 – Four-terminal resistor .................................................................................. - 19 -

41 Figure D.4 – Five-terminal resistor ................................................................................... - 19 -

42 Figure D.5 – Four-terminal coaxial resistor ...................................................................... - 20 -

43 Figure D.6 – Two-terminal-pair resistor ............................................................................ - 20 -

44 Figure D.7 – Four-terminal-pair resistor ........................................................................... - 21 -

46 Table 1 –limits of the AC resistance relative uncertainty .................................................... - 8 -

47 Table 2 –limits of the AC/DC difference ............................................................................. - 8 -

48 Table 3 –Upper limit of the nominal range of use for frequency .......................................... - 9 -

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50 INTERNATIONAL ELECTROTECHNICAL COMMISSION
51 ____________
53 LABORATORY RESISTORS –
55 Part 2: Laboratory AC resistors
59 FOREWORD

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

61 all national electrotechnical committees (IEC National Committees). The object of IEC is to promote

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

63 this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,

64 Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC

65 Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested

66 in the subject dealt with may participate in this preparatory work. International, governmental and non-

67 governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely

68 with the International Organization for Standardization (ISO) in accordance with conditions determined by

69 agreement between the two organizations.

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

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

72 interested IEC National Committees.

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

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

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

76 misinterpretation by any end user.

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

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

79 between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in

80 the latter.

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

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

83 services carried out by independent certification bodies.

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

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

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

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

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

89 Publications.

90 8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is

91 indispensable for the correct application of this publication.

92 9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of

93 patent rights. IEC shall not be held responsible for identifying any or all such patent rights.

94 International Standard IEC 60477-2 has been prepared by IEC technical committee 85:

95 Measuring equipment for electromagnetic quantities.

96 This second edition cancels and replaces the first edition published in 1979, Amendment

97 1:1997. This edition constitutes a technical revision.

98 This edition includes the following significant technical changes with respect to the previous

99 edition:
100 – replaced a.c. with AC according IEC 60050-151:2001, 151-15-01;
101 – extended the resistor frequency scope to 1 MHz of this document;
102 – updated the classification according the AC resistor construction;
103 – updated the terms and definition according to IEC 60050 series;
104 – added the definition of AC/DC difference of an AC resistor;

105 – added the resistor classification according the AC resistance or AC/DC difference index;

106 – updated the safety symbols and requirements according to IEC 60047;
107 – added the three-element equivalent circuit of an AC resistor in Annex C;
108 – added the annex on constructions of AC resistors.
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109 The text of this International Standard is based on the following documents:
110
FDIS Report on voting
XX/XX/FDIS XX/XX/RVD
111

112 Full information on the voting for the approval of this International Standard can be found in

113 the report on voting indicated in the above table.

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

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

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

117 the specific document. At this date, the document will be
118 • reconfirmed,
119 • withdrawn,
120 • replaced by a revised edition, or
121 • amended.
122

123 The National Committees are requested to note that for this document the stability date

124 is 2025.

125 THIS TEXT IS INCLUDED FOR THE INFORMATION OF THE NATIONAL COMMITTEES AND WILL BE

126 DELETED AT THE PUBLICATION STAGE.
127
128
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129 LABORATORY RESISTORS –
130
131 Part 2: Laboratory AC resistors
132
133
134
135 1 Scope

136 This part of IEC 60477 applies to resistors intended as laboratory AC resistors for use over a

137 range of frequencies from DC up to a stated frequency which is not in excess of 1 MHz. Such

138 resistors are hereinafter referred to as “AC resistors”.

139 In addition to satisfying the requirements of IEC 60477, resistors satisfying the requirements

140 of this standard are designed to have a small variation of resistance and a small phase

141 displacement over the stated frequency range.

142 Because of the uncertainties in AC properties which can result from stray inductances, stray

143 capacitances, eddy currents, dielectric absorption effects and skin effect, the AC resistors to

144 which this standard applies are classified according to their construction (see Annex D), as

145 follows:

146 a) Two-terminal resistor which each of one terminal both for current and potential;

147 b) Three-terminal resistor which has one more shield terminal (also could be called as guard

148 terminal) connected to the electric screen than the two-terminal resistor to reduce the

149 stray capacitances effect;

150 c) Four-terminal resistor which has independent current terminals and potential terminals to

151 reduce the stray inductances and contact resistances;

152 d) Five-terminal resistor which has one more shield terminal than the four-terminal resistor;

153 e) Four-terminal coaxial resistor which has two terminal-pairs with the outer shield

154 conductors working as the low terminal of current or potential;

155 f) Two-terminal-pair resistor which has two terminal-pairs with the outer shield conductors

156 working as the return path for the signal current (not grounded);

157 g) Four-terminal-pair resistor which has four terminal-pairs with the outer shield conductors

158 working as the return path for the signal current (not grounded) to eliminate the effect of

159 mutual coupling between the current and potential leads.
160
161 2 Normative references

162 The following documents are referred to in the text in such a way that some or all of their

163 content constitutes requirements of this document. For dated references, only the edition

164 cited applies. For undated references, the latest edition of the referenced document (including

165 any amendments) applies.
166 IEC 60477, Laboratory DC resistors
167 3 Terms and definitions

168 For the purposes of this document, the following terms and definitions apply.

169 ISO and IEC maintain terminological databases for use in standardization at the following

170 addresses:
171 ISO Online browsing platform: available at http://www.iso.org/obp
172 IEC Electropedia: available at http://www.electropedia.org/
173 3.1
174 equivalent electric circuit

175 circuit composed of ideal circuit elements which has, at the terminals or ports, a behaviour

176 equivalent to that of a given electric or magnetic circuit or device

177 Note 1 to entry: Equivalent electric circuits can also be used to represent other kinds of devices or phenomena.

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178 [SOURCE: IEC 60050-131:2002,131-15-07]
179 3.2
180 circuit element

181 in electromagnetism, mathematical model of a device characterized by one or more relations

182 between integral quantities
183 [SOURCE: IEC 60050-131:2002,131-11-03]
184 3.3
185 equivalent circuit of an AC resistor

186 electrical electric circuit which has the same AC characteristics as a resistor, would have an

187 impedance equal to the resistor under specified operating conditions

188 Note 1 to entry: Specified operating conditions should include working frequency and voltage.

189 3.4
190 two-element equivalent circuit of an AC resistor

191 an equivalent circuit of an AC resistor with two elements under specified operating conditions

192 Note 1 to entry: two-element equivalent circuit of an AC resistor is given by either an equivalent AC resistance,

193 R in series with an equivalent inductance, L or an equivalent AC resistance, R in parallel with an equivalent

s s p
194 capacitance, C (see Annexes C)
p .
195 3.5
196 three-element equivalent circuit of an AC resistor

197 an equivalent electric circuit of an AC resistor with three elements under specified operating

198 conditions
199 3.6
200 equivalent AC resistance of an AC resistor
201 AC resistance

202 value of resistance (R or R ) which is the AC resistive component of the resistor

s p

203 Note 1 to entry: The AC resistance is usually taken as the equivalent series resistance R , for resistors Category

204 A, and as the equivalent parallel resistance R , for resistors Category C (see Annexes B).

205 3.7
206 terminal pair

207 port consisting of two terminals such that the electric current directed from an external circuit

208 or device to one terminal is identical with the current directed from the other terminal to the

209 external circuit or device
210 [SOURCE: IEC 60050-131:2002,131-12-63]
211 3.8
212 time constant
213 τ
−tτ
F t A+Be

214 time τ in the expression () of a quantity F growing or decaying exponentially

−tτ

215 towards a constant value A with increasing time t, or in the expression F t A+ f t e of

() ()
216 an exponentially damped oscillation, where f is a periodic function of time

217 Note 1 to entry: for a quantity growing or decaying exponentially towards a constant value the duration of a time

218 interval, at the end of which the absolute value of the difference between that constant value and the value of the

219 variable quantity has decreased to e times of the absolute value of the difference at the beginning of the interval,

220 where e is the base of natural logarithms.

221 Note 2 to entry: For resistor, at any particular frequency, it is defined as either: L /R , or R C whichever yields a

s s p p

222 positive value (see Appendix C). For determining the time constant, the DC resistance may be used instead of the

223 equivalent AC resistance.

224 Note 3 to entry: For resistor used three-element equivalent circuit expressed, it is approximately equal to:

225 , or (see Appendix C) .
CR−
−CR
R R

226 Note 4 to entry: The phase displacement of the current flowing through the resistor from the voltage appearing

227 across it with a time constant L /R or is such that the current is lagging, and that with a time constant

s s
−CR
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228 R C or is leading when L and C , have positive value, L and L being expressed in henrys, R , R and R

p p s p s s p
CR−
229 in ohms and C and C in farads.

230 [SOURCE: IEC 60050-103:2009, 103-05-26, modified – Note 2, Note 3 and Note 4 to entry

231 has been added to adapt to usage in AC resistor technology]
232 3.9
233 time constant index
234 conventional designation of a time constant by a number or symbol

235 Note 1 to entry: In this standard, it is expressed in seconds using the appropriate SI prefix.

236 3.10
237 AC/DC difference

238 difference between the equivalent AC resistance at a stated frequency and the DC resistance,

239 expressed in percentage (%) of the DC resistance
240 3.11
241 AC/DC difference index

242 number which designates the limit of the AC/DC difference with in nominal range of use for

243 frequency, expressed in %
244 3.12
245 frequency index

246 number which designates the upper limit of the nominal range of use for frequency, expressed

247 in hertz (see Table 3) using the appropriate SI prefix
248 3.13
249 skin effect

250 for an alternating electric current in a conductor, phenomenon in which the current density is

251 greater near the surface than in the interior of the conductor

252 Note 1 to entry: The skin effect increases the resistance and decreases the inductance of a conductor with the

253 frequency of the electric current.

254 Note 2 to entry: The skin effect occurs also in the more general case of any time-varying current.

255 [SOURCE: IEC 60050-121:1998, 121-13-18]
256 3.14
257 residual inductance

258 inductance value between the points of connection of a multiple or multi-dial AC resistor

259 having switching devices with a zero position, when all switching elements are set to the zero

260 position
261 4 Resistor characterization
262 AC resistors satisfying this standard are characterized:
263 h) by classes related to their DC accuracy as specified in IEC 60477,

264 i) by classes related to their equivalent AC resistance as specified in Sub clause 5.1.2 or

265 AC/DC difference indices as specified in Sub-clause 5.1.3 and,
266 j) by time constant indices as specified in Sub-clause 5.1.4 and,
267 k) by frequency indices as specified in Sub-clause 6.2.
268
269 5 General requirements
270 5.1 DC resistance, AC resistance and time constant
271 The DC characteristics of an AC resistor shall be as specified in IEC 60477.

272 The equivalent AC resistance of an AC resistor characterized by class related to the AC

273 resistance shall comply with the limits of relative uncertainty for specified for their AC

274 resistance class index in Table 1 at initial calibration.
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275 Table 1 –limits of the AC resistance relative uncertainty
AC resistance
0.00001 0.00002 0.00005 … 2 5 10
class index
limits of relative
uncertainty for 0.00001% 0.00002% 0.00005% … 2% 5% 10%
AC resistance

276 Note 1 The value of the AC resistance of a given resistor is somewhat dependent on the frequency at which it is

277 measured. However, as the purpose here is to affect a classification of resistors, measurements at 1 kHz (or lower)

278 are here generally adequate.

279 The AC/DC difference of an AC resistor characterized by AC/DC difference index shall comply

280 with the limits of AC/DC difference specified for their AC/DC difference index in Table 2 at

281 initial calibration.
282 Table 2 –limits of the AC/DC difference
AC/DC
0.000001 0.000002 0.000005 … 0.2 0.5 1
difference index
limits of the
AC/DC ±0.000001% ±0.000002% ±0.000005% … ±0.2% ±0.5% ±1%
difference
283 Note 2 Measurements at 1 kHz (or lower) are here generally adequate.

284 Note 3 An AC resistor shall choose either AC resistance class index or AC/DC difference index to show the

285 equivalent AC resistance character.

286 The time constant of an AC resistor shall not exceed the appropriate value of the time

287 constant index selected from the sequence:
288 • 1 ns, 2 ns, 5 ns, 10 ns, …100 μs.

289 Note 4 The value of the time constant of a given resistor is also somewhat dependent on the frequency at which it

290 is measured. Measurements at 1 kHz (or lower) are here generally adequate as same as the measurements of AC

291 resistance.
292 5.2 Multiple resistors

293 Multiple resistors, excluding multi-dial resistors, may have different AC resistance class or

294 AC/DC difference and time constant index for each selectable value.

295 For a multiple resistor in which the lowest selectable resistance value is nominally zero, the

296 manufacturer shall state the value of the residual inductance under this condition.

297 5.3 Multi-dial resistors

298 Multi-dial resistors shall have a single AC resistance class index or AC/DC difference index

299 and a single time constant index for all selectable values on any dial used alone. The several

300 dials may each have a different AC resistance class index or AC/DC difference index and a

301 different time constant index.

302 The AC resistance class index or AC/DC difference index of a given dial shall also apply at

303 any setting of the dial when that dial is used in conjunction with any setting of any dial(s)

304 inferior to it in value.

305 The time constant index of a given dial shall also apply at any setting of the dial when that

306 dial is used in conjunction with any setting of any dial(s) inferior to it in value.

307 5.4 Connecting leads

308 Separate current and potential connections shall be made to a resistor having a pair of

309 terminals for each port of connection, unless other conditions are stated by the manufacturer.

310 The mutual inductances between the current and potential leads and between each of these

311 leads and the resistor shall be minimized.

312 The leads making connection to a resistor having a single terminal for each port of connection

313 shall be arranged so as to minimize their inductance.

314 Note 1 This is particularly important for resistors of values of 10Ω and lower.

315 The leads making connection to a resistor shall not alter significantly the equivalent parallel

316 capacitance, if necessary, by the provision of screen for each lead and by the use of an

317 appropriate measuring circuit.
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318 Note 2 The magnitude of capacitance that will cause a significant alteration will depend upon the value of the

319 resistance and the time constant.
320 5.5 Conditions for the determination of DC and AC characteristics

321 All tests of DC characteristics shall be carried out as specified in IEC 60477

322 Note 1 At low frequencies, the uncertainty of an AC resistor is essentially the same as its uncertainty at DC

323 Note 2 At higher frequencies, an additional variation as specified by Sub-clause 6.1 is permitted.

324 All tests of AC characteristics shall be carried out under the reference conditions specified in

325 IEC 60477.

326 The AC resistance of an AC resistor shall be measured at a frequency of 1 kHz or at the

327 frequency corresponding to its frequency index if the latter is lower (see Clause 6).

328 The time constant of an AC resistor shall be measured at a frequency of 1 kHz or at the

329 frequency corresponding to its frequency index if the latter is lower (see Clause 6).

330 The residual inductance of an AC resistor (see Sub-clause 5.2.2) shall be measured with the

331 resistor connected as in normal use and at a frequency of 1 kHz or at the frequency

332 corresponding to its frequency index if the latter is lower (see Clause 6).

333 A resistor having a shield terminal (see Items b) and d) of Sub-clause 1.3) shall be tested with

334 the screen connected as specified by the manufacturer.

335 A resistor not having a shield terminal (see Item a) and c) of Sub-clause 1.3) shall be tested

336 within an earthed conductive enclosure as specified by the manufacturer. If this enclosure is

337 not specified, the resistor shall be tested within an earthed conductive enclosure separated

338 from the surface of the resistor by between 10 mm and 20 mm at all places.

339 A resistor having terminal-pairs (see Items e), f) and g) of Sub-clause 1.3) shall be tested with

340 the terminal-pair connected as specified by the manufacturer.
341 Any other necessary conditions shall be stated by the manufacturer.

342 When necessary, details of the testing method shall be agreed between the manufacturer and

343 the user.
344 6 Permissible variations

345 Changes in influence quantities over the nominal ranges of use specified in IEC 60477 will

346 cause no significant effect on the AC characteristics of the resistor. Requirements relating to

347 variations of AC characteristics other than those due to frequency are therefore not included

348 in this standard.

349 The upper limit of the nominal range of use for frequency shall be designated using the

350 appropriate frequency index selected from Table 3.
351 Tabl
...