Laboratory d.c. resistors

Definitions; classification; limits of intrinsic errors: permissible variations; further requirements; markings; symbols.

Gleichstrom-Meßwiderstände

Résistances de laboratoire à courant continu

Limites de l'erreur intrinsèque; conditions pour la détermination des valeurs intrinsèques; variations admissibles; prescriptions diverses; marquage; symboles.

Laboratorijski upori za enosmerni tok (IEC 60477:1974)

General Information

Status
Published
Publication Date
31-Aug-2000
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
01-Sep-2000
Due Date
01-Sep-2000
Completion Date
01-Sep-2000

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EN 60477:2000
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2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Laboratorijski upori za enosmerni tok (IEC 60477:1974)Gleichstrom-MeßwiderständeRésistances de laboratoire à courant continuLaboratory d.c. resistors17.220.20Measurement of electrical and magnetic quantitiesICS:Ta slovenski standard je istoveten z:EN 60477:1997SIST EN 60477:2000en01-september-2000SIST EN 60477:2000SLOVENSKI
STANDARD



SIST EN 60477:2000



SIST EN 60477:2000



SIST EN 60477:2000



NORMEINTERNATIONALEINTERNATIONALSTAN DARDCEIIEC60477Première éditionFirst edition1974-01Résistances de laboratoire à courant continuLaboratory d.c. resistors© IEC 1974 Droits de reproduction réservés — Copyright - all rights reservedAucune partie de cette publication ne peut être reproduite niutilisée sous quelque forme que ce soit et par aucunprocédé, électronique ou mécanique, y compris la photo-copie et les microfilms, sans raccord écrit de l'éditeur.No part of this publication may be reproduced or utilized inany form or by any means, electronic or mechanical,including photocopying and microfilm, without permission inwriting from the publisher.International Electrotechnical Commission3, rue de Varembé Geneva, SwitzerlandTelefax: +41 22 919 0300e-mail: inmail@iec.chIEC web site http: //www.iec.chCommission Electrotechnique InternationaleInternational Electrotechnical CommissionMewayHapogHaH 3neKTpoTexHN4ecnaa HOMHCCHfI•CODE PRIXPRICE CODEPour prix, voir catalogue en vigueurFor price, see current catalogueIEC•NSIST EN 60477:2000



— 3 —CONTENTSPageFOREWORD 5PREFACE 5Clause1.Scope 72.Definitions72.1 General terms 72.2 Characteristic values 92.3 Influence quantities, reference conditions, nominal range of use 92.4 Errors and variations 112.5 Accuracy, accuracy class, class index 113.Classification 114.Limits of intrinsic error 135.Conditions for the determination of intrinsic errors 156.Permissible variations 156.1 Limits of variation 156.2 Conditions for the determination of the variations 176.3 Influence of self-heating (power dissipation) 176.4 Influence of position 197.Further electrical and mechanical requirements 197.1 Voltage tests and other safety requirements 197.2 Insulation resistance 197.3 Conditions of transport, storage and use 197.4 Point of connection 197.5 Provision of temperature measuring facilities 198.Markings and symbols 21APPENDIXAl — Thermoelectric effects 27A2 — Reference range and nominal range of use 27A3 — Example of marking for a single resistor 29A4 — Example of marking for a five-decade resistor 29SIST EN 60477:2000



— 5 —INTERNATIONAL ELECTROTECHNICAL COMMISSIONLABORATORY D.C. RESISTORSFOREWORD1)The formal decisions or agreements of the I EC on technical matters, prepared by Technical Committees on which all the NationalCommittees having a special interest therein are represented, express, as nearly as possible, an international consensus of opinionon 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.3)In order to promote international unification, the IEC expresses the wish that all National Committees should adopt the text ofthe IEC recommendation for their national rules in so far as national conditions will permit. Any divergence between the IECrecommendations and the corresponding national rules should, as far as possible, be clearly indicated in the latter.PREFACEThis recommendation has been prepared by Sub-Committee 13B, Indicating Instruments, of I EC TechnicalCommittee No. 13, Measuring Instruments.Drafts were discussed at the meetings held in Budapest in 1970 and in Stresa in 1971. As a result of this lattermeeting, a final draft, document 13B(Central Office)38, was submitted to the National Committees for approvalunder the Six Months' Rule in October 1972.The following countries voted explicitly in favour of publication:ArgentinaHungaryAustraliaIsraelAustriaJapanBelgiumPortugalCanadaSouth AfricaDenmark(Republic of)EgyptSwedenFinlandTurkeyFranceUnited KingdomGermanyYugoslaviaSIST EN 60477:2000



— 7 --LABORATORY D.C. RESISTORS1. Scope1.1 This recommendation applies to resistors intended for use as laboratory d.c. resistors (hereinafter referred toas "resistors") comprising single or multiple resistors of accuracy Classes 0.0005 . 0.2 (5 ppM . 2000 ppM)and single or multi-decade resistors of accuracy Classes 0.0005 . 5 (5 ppM . 50 000 ppM).1.2 This recommendation does not apply to:—resistors which are intended for use solely as permanent mounted circuit components,—resistors used on alternating current or on pulsed currents,—series resistors and shunts which are considered as accessories of electrical measuring instruments in therelevant IEC publications.Note. — Examples are the following publications:Publication 51: Recommendations for Direct Acting Indicating Electrical Measuring Instruments and Their Accessories.Publication 258: Direct Recording Electrical Measuring Instruments and Their Accessories.2. Definitions2.1 General terms2.1.1 Point of connectionA single terminal for both current and potential or a pair of terminals, one each for current and for potential.2.1.2 Single resistorA device which provides a single definite resistance value between certain points of connection.2.1.3 Multiple resistorAn assembly comprising a number of resistors which are accessible either singly or in combination and whichprovides definite resistance values between certain points of connection.2.1.4 Measurement standard resistorA single or multiple resistor intended for reference measurement purposes.2.1.5 Resistance decadeA multiple resistor which, by means of a switching device, generally allows the selection of a combination ofresistance values rising in equal steps, each step corresponding to an increment of a decadic resistance value(e.g. 0.1 S2 or 1 52 or 10 S2 .).Note. — A resistance decade generally allows a selection of 10, 11 or 12 resistance values (including zero).2.1.6 Multi-decade resistorA multiple resistor comprising a number of resistance decades which are generally connected in series.2.1.7 Leakage current screenA path which conducts leakage currents to earth or to a fixed point so that they do not pass through the resistoror other parts of the measuring circuit.2.1.8 Electrostatic screenA covering in the form of metal foil, fine mesh wire netting or conductive coating intended to protect the enclosedspace from external electrostatic effects.SIST EN 60477:2000



— 9 —2.2 Characteristic values2.2.1 Nominal valueA value which designates a single resistor or a selected combination of a multiple resistor.2.2.2 Actual valueA value obtained under specified test Conditions and at a specified time. For a multiple resistor with switchingdevices having a zero position, the actual value for a given setting is the value obtained for that setting minus theactual residual resistance (see Sub-clause 2.2.5.2).Note. — Since the true value cannot be determined by measurement, a value traceable to national measurement standards, or a measure-ment standard agreed upon by manufacturer and user, and having a stated uncertainty, is used in place of the truevalue. This value, known as the actual value, may be found by applying small corrections according to the known variationswith influence quantities, if necessary.2.2.3 Certified valueThe actual value, with its associated uncertainty, at the date when it is reported in the accompanying document.2.2.4 Fiducial valueA value to which the errors of a resistor are referred in order to specify its accuracy. The fiducial value correspondsto:—the selected value for a resistance decade,—the certified value for a single or a multiple resistor of Classes 0.0005 . 0.01 (5 ppM . 100 ppM),—the nominal value for a single or a multiple resistor of Classes 0.02 . 5 (200 ppM . 50 000 ppM).2.2.5 Residual resistanceThe resistance value between the points of connection of a multiple resistor having switching devices with azero position, when all switching elements are set to the zero position.2.2.5.1 Nominal residual resistanceA rounded off value which designates the value of the residual resistance.2.2.5.2 Actual residual resistanceA value of residual resistance obtained under specified conditions and at a specified time.2.3 Influence quantities, reference conditions, nominal range of use2.3.1 Influence quantityA quantity which is liable to cause unwanted variation in the value of a resistor.Note. — Generally, it covers such quantities as ambient temperature and humidity, position and power dissipation. These quantitieswill have reference ranges and nominal ranges of use, which are given in the appropriate tables.2.3.2 Limiting values of an influence quantityExtreme values which an influence quantity may assume without the resistor being damaged or permanentlyaltered in such a way that it no longer satisfies the requirements of its accuracy class, e.g. the limiting powerdissipation (see Sub-clause 6.3.2).2.3.3 Reference conditionsThe specified conditions under which the resistor meets the requirements concerning intrinsic errors. For eachinfluence quantity, these conditions may be either a fixed value or a range of values.2.3.3.1 Reference valueA single value of an influence quantity at which (within the tolerance stated in Clause 5) the resistor complieswith the requirements concerning intrinsic errors.SIST EN 60477:2000



— 11 —2.3.3.2 Reference rangeA range of values of an influence quantity within which the resistor complies with the requirements concerningintrinsic errors.2.3.4 Nominal range of useA range of values which each influence quantity can assume without causing a variation exceeding the limitsspecified in Clause 6.2.4 Errors and variations2.4.1 ErrorThe value of the deviation of the actual value from the fiducial value. It is expressed in per cent or in parts permillion of the fiducial value.Note. — It is recommended that the following convention be adopted:error = actual value — fiducial value.2.4.2 Intrinsic errorAn error determined under reference conditions.2.4.3 VariationThe difference between the actual values, expressed in per cent or in parts per million of the fiducial value,determined when an influence quantity assumes successively two specified values, all other influence quantitiesremaining within their reference conditions.2.5 Accuracy, accuracy class, class index2.5.1 AccuracyThe accuracy of a resistor is defined by the limits of intrinsic error and the limits of variations due to influencequantities.2.5.2 Accuracy classA class of resistors the accuracy of all of which can be designated by the same number if they comply with allthe requirements of this recommendation.2.5.3 Class indexThe number which designates the accuracy class.3. Classification3.1 Resistors satisfying this recommendation are classified according to their accuracy class (as defined inSub-clause 2.5.2) in the classes designated by the class indices given in Table I.There are two permissible methods of expressing the class index of a resistor. They are both related to the fiducialvalue. One is expressed as a percentage of the fiducial value, the other is expressed in parts per million (ppM) of it.The class index of a resistor can be given using either method or both methods.TABLE IClass indices for resistorsExpressed in %0.00050.0010.0020.0050.010.020.050.10.2Expressed in ppM51020501002005001 0002 000SIST EN 60477:2000



— 13 —3.2 For multi-decade resistors, each decade may have a different class index (see example in Appendix A4).Some of the decades may have a class index taken from Table II.TABLE IIClass indices for some resistance decades of multi-decade resistors onlyExpressed in %0.5125Expressed in ppM5 00010 00020 00050 0004. Limits of intrinsic error4.1 Resistors shall comply with the limits of intrinsic error specified for their respective accuracy class in Table IIIfor the duration of one year from the date of certification associated with delivery or another date (such as thedate of initial certification) agreed upon by manufacturer and user.This requirement applies only if the working and storage conditions specified by the manufacturer are compliedwith.Note. — For resistors, constancy with regard to time is a characteristic of decisive importance. Here, it is specified only for the durationof one year, but experience has shown that the rate of change due to ageing effects decreases with time.4.1.1 The difference at initial certification between the actual value and the nominal value for resistors ofClasses 0.0005 . 0.01 (5 ppM . 100 ppM) shall not exceed f 0.01% (± 100 ppM) of the nominal value .4.1.2 The actual value at initial certification and the nominal value for resistors of Classes 0.02 . 5(200 ppM . 50 000 ppM) shall not differ by more than an amount corresponding to the class index.4.2 In a multiple resistor, the actual value relates to each resistor, singly or in combination, the value of whichis stated and which is intended for measurement and is directly accessible by terminals or other connection means.TABLE IIILimits of intrinsic error expressed as a proportion of the fiducial value and limits for initial certificationClass indexLimits of intrinsic errorLimits for initial certification *ppM%ppM%ppM0.00055± 0.0005±50.00110± 0.001±10± 0.01±1000.00220f 0.002±200.00550± 0.005±500.01100± 0.01±1000.02200± 0.02±200± 0.02±2000.05500± 0.05±500± 0.05±5000.11 000± 0.1±1 000± 0.1±1 0000.22000±0.2± 2000±0.2± 20000.55000± 0.5f 5000± 0.5± 5000110 000± 1± 10 000± 1± 10 000220 000± 2± 20 000± 2± 20 000550 000± 5± 50 000± 5± 50 000* See Sub-clauses 4.1.1 and 4.1.2.SIST EN 60477:2000



— 15 —4.3 For a multiple resistor with switching devices each having a zero position, the manufacturer shall state thenominal value of the residual resistance with its tolerances if it is higher than 50% of a value corresponding tothe class index of the smallest resistance step.5. Conditions for the determination of intrinsic errors5.1 The reference conditions relative to each of the influence quantities are shown in Table IV.TABLE IVReference conditions and tolerances of the influence quantitiesInfluence quantityReference conditions, unless markedTolerance permitted for testingpurposes applicable for a singlereference value 1)Ambient temperature20 °C1/10 of the nominal range of use, but not(atmosphere, oil bath, etc.)less than ± 0.1 °C 2)Relative humidity50%40% . 60% 3>Dissipated powerShall be specified in all cases—CoolingNone—PositionAny—External connectionsAny—1> For a reference range, no tolerance is allowed.2) For resistors of Class 0.0005 (5 ppM), as an exception the tolerance is ± 0.1 °C and not 1/lo of the nominal ranges of use(see Table V).3) Considerable care may have to be taken in order to ensure that this permitted tolerance is not exceeded.5.2 The reference values are for stable conditions. Any change in conditions shall be followed by a sufficienttime under reference conditions to allow equilibrium to be established before measurements are made.5.3 The measurement of resistance values shall be made with a substantially constant value of direct currentwhich shall have been applied for a time that is sufficient for a constant resistance value to have been attainedunless a shorter time or range of time is specified by the manufacturer. These requirements shall also apply tocurrent that is interrupted or reversed.Notes 1. — The value of resistance is taken as the average (mean) of the values determined using the two directions of the current.2. — Resistance may vary or appear to vary with time because of:a)transient effects due to reactance either inductive or capacitive;b)dielectric absorption;c)polarization voltage;d)thermo-electric Seebeck, Peltier and Thompson effects (see Appendix Al).Due to the complexity of these causes of change, it is not generally reliable to obtain a direct current value of resist-ance by extrapolation from measurements of resistance using alternating current over a range of low frequencies.6. Permissible variations6.1 Limits of variationWhen the resistor is under the condit
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