EN 60051-1:1998

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Direkt wirkende anzeigende elektrische Meßgeräte und ihr Zubehör - Meßgeräte mit Skalenanzeige -- Teil 1: Definitionen und allgemeine Anforderungen für alle Teile dieser NormAppareils mesureurs électriques indicateurs analogiques à action directe et leurs accessoires -- Partie 1: Définitions et prescriptions générales communes à toutes les partiesDirect acting indicating analogue electrical measuring instruments and their accessories -- Part 1: Definitions and general requirements common to all parts17.220.20Measurement of electrical and magnetic quantities01.040.17Meroslovje in merjenje. Fizikalni pojavi (Slovarji)Metrology and measurement. Physical phenomena (Vocabularies)ICS:Ta slovenski standard je istoveten z:EN 60051-1:1998SIST EN 60051-1:2000en01-september-2000SIST EN 60051-1:2000SLOVENSKI
STANDARDSIST EN 60051-1:1995/A2:2000SIST EN 60051-1:1995/A1:2000SIST EN 60051-1:19951DGRPHãþD

NORMEINTERNATIONALECEIIECINTERNATIONALSTANDARD60051-1Cinquième éditionFifth edition1997-12Appareils mesureurs électriquesindicateurs analogiques à action directeet leurs accessoires –Partie 1:Définitions et prescriptions généralescommunes à toutes les partiesDirect acting indicating analogue electricalmeasuring instruments and their accessories –Part 1:Definitions and general requirementscommon to all parts Commission Electrotechnique Internationale International Electrotechnical
CommissionPour prix, voir catalogue en vigueurFor price, see current
catalogueÓ IEC 1997
Droits de reproduction réservés
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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 l'accord 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.ch IEC web site
http: //www.iec.chCODE PRIXPRICE CODEXSIST EN 60051-1:2000

60051-1 © IEC:1997– 3 –CONTENTSPageFOREWORD.7Clause1General.111.1Scope.111.2Normative references.112Definitions.132.1General terms.132.2Description of instruments according to their method of operation.192.3Constructional features of instruments.232.4Characteristic features of instruments.292.5Characteristic values.292.6Influence quantity, reference conditions, nominal range of useand preconditioning.312.7Errors and variations.332.8Accuracy, accuracy class and class index.333Description, classification and compliance.353.1Description.353.2Classification.353.3Compliance with the requirements of this standard.354Reference conditions and intrinsic errors.354.1Reference conditions.354.2Limits of intrinsic error, fiducial value.375Nominal range of use and variations.415.1Nominal range of use.415.2Limits of variations.415.3Conditions for the determination of variations.456Further electrical and mechanical requirements.456.1Voltage tests, insulation tests and other safety requirements.476.2Damping.476.3Self-heating.476.4Permissible overloads.496.5Limiting values of temperature.496.6Deviation from zero.497 Constructional requirements.497.1Sealing to prevent access.497.2Scales.497.3Indication of out-of-range values of the measurand.537.4Preferred values.537.5Adjusters, mechanical and/or electrical.537.6Effects of vibration and shock.55SIST EN 60051-1:2000

60051-1 © IEC:1997– 5 –Page8Information, general markings and symbols.578.1Information.578.2Markings, symbols and their locations.598.3Markings relating to the reference values and nominal ranges of useof influence quantities.619Markings and symbols for terminals.739.1Requirements for markings.739.2Earthing (grounding) terminals.739.3Measuring circuit terminals.749.4Special markings for terminals.7510Tests to prove compliance with this standard.75Annex A-1 – Tests.77Annex B-1 – Permissible errors and variations.79SIST EN 60051-1:2000

60051-1 © IEC:1997– 7 –INTERNATIONAL ELECTROTECHNICAL COMMISSION_________DIRECT ACTING INDICATING ANALOGUE ELECTRICAL MEASURINGINSTRUMENTS AND THEIR ACCESSORIES –Part 1: Definitions and general requirements common to all partsFOREWORD1)The IEC (International Electrotechnical Commission) is a worldwide organization for standardization comprisingall national electrotechnical committees (IEC National Committees). The object of the IEC is to promoteinternational co-operation on all questions concerning standardization in the electrical and electronic fields. Tothis end and in addition to other activities, the IEC publishes International Standards. Their preparation isentrusted to technical committees; any IEC National Committee interested in the subject dealt with mayparticipate in this preparatory work. International, governmental and non-governmental organizations liaisingwith the IEC also participate in this preparation. The IEC collaborates closely with the International Organizationfor Standardization (ISO) in accordance with conditions determined by agreement between the twoorganizations.2)The formal decisions or agreements of the IEC on technical matters express, as nearly as possible, aninternational consensus of opinion on the relevant subjects since each technical committee has representationfrom all interested National Committees.3)The documents produced have the form of recommendations for international use and are published in the formof standards, technical reports or guides and they are accepted by the National Committees in that sense.4)In order to promote international unification, IEC National Committees undertake to apply IEC InternationalStandards transparently to the maximum extent possible in their national and regional standards. Anydivergence between the IEC Standard and the corresponding national or regional standard shall be clearlyindicated in the latter.5)The IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for anyequipment declared to be in conformity with one of its standards.6)Attention is drawn to the possibility that some of the elements of this International Standard may be the subjectof patent rights. The IEC shall not be held responsible for identifying any or all such patent rights.International Standard IEC 60051-1 has been prepared by IEC technical committee 85:Measuring equipment for electromagnetic quantities.This fifth edition cancels and replaces the fourth edition published in 1984, amendment 1(1994) and amendment 2 (1995). It constitutes a technical revision.The text of this standard is based on the fourth edition, amendment 1, amendment 2 and thefollowing documents:FDISReport on voting85/166/FDIS85/177/RVDFull information on the voting for the approval of this standard can be found in the report onvoting indicated in the above table.SIST EN 60051-1:2000

60051-1 © IEC:1997– 9 –INTRODUCTIONIEC 60051 is published in separate parts according to the following structure and under thegeneral title Direct acting indicating analogue electrical measuring instruments and theiraccessories.Part 1:Definitions and General Requirements Common to all Pans.Part 2:Special Requirements for Ammeters and Voltmeters.Part 3:Special Requirements for Wattmeters and Varmeters.Part 4:Special Requirements for Frequency Meters.Part 5:Special Requirements for Phase Meters, Power Factor Meters and Synchroscopes.Part 6:Special Requirements for Ohmmeters (Impedance Meters) and Conductance Meters.Part 7:Special Requirements for Multi-function Instruments.Part 8:Special Requirements for Accessories.Part 9:Recommended Test Methods.Parts 2 to 9 are not complete in themselves and shall be read in conjunction with this Part 1.All of these pans are arranged in the same format and a standard relationship between subjectand clause number is maintained throughout. In addition, tables, figures and annexes add asuffix to the part number in order to differentiate the pans. This re-arrangement will assist thereader of IEC 60051 to distinguish information relating to the different types of instruments.SIST EN 60051-1:2000

60051-1 © IEC:1997– 11 –DIRECT ACTING INDICATING ANALOGUE ELECTRICAL MEASURINGINSTRUMENTS AND THEIR ACCESSORIES –Part 1: Definitions and general requirements common to all parts1 General1.1 ScopeThis standard applies to direct acting indicating electrical measuring instruments having ananalogue display, such as:–ammeters and voltmeters;–wattmeters and varmeters;–frequency meters of pointer and vibrating-reed types;–phasemeters, power-factor meters and synchroscopes;–ohmmeters, impedance meters and conductance meters;–multi-function instruments of the above types.It also applies to certain accessories used with these instruments, such as:–shunts;–series resistors and impedance elements.If other accessories are associated with instruments, this standard is applicable to thecombination of the instrument and the accessory provided that the adjustments have beenmade for the combination.This standard also applies to a direct acting indicating electrical measuring instrument whosescale marks do not correspond directly to its electrical input quantity, provided that therelationship between them is known.This standard also applies to instruments and accessories having electronic devices in theirmeasuring and/or auxiliary circuits.This standard does not apply to special purpose instruments which are covered by their ownIEC standards.This standard does not apply to special purpose devices which are covered by their own IECstandards when they are used as accessories.This standard does not contain either requirements for protection against environmentalconditions or the relevant tests. However, when necessary, and then only by agreementbetween the manufacturer and the user, tests to approximate the conditions of use may beselected from IEC 60068.This standard does not specify requirements concerning dimensions of instruments oraccessories (for the former, see IEC 60473).SIST EN 60051-1:2000

60051-1 © IEC:1997– 13 –1.2 Normative referencesThe following normative documents contain provisions which, through reference in this text,constitute provisions of this part of IEC 60051. At the time of publication, the editions indicatedwere valid. All normative documents are subject to revision, and parties to agreements basedon this part of IEC 60051 are encouraged to investigate the possibility of applying the mostrecent editions of the normative documents indicated below. Members of IEC and ISO maintainregisters of currently valid International Standards.IEC 60027: Letter symbols to be used in electrical technologyIEC 60050(301), (302), (303):1983, International Electrotechnical Vocabulary (IEV) – Chapter301: General terms on measurements in electricity – Chapter 302: Electrical measuringinstruments – Chapter 303: Electronic measuring instrumentsIEC 60051-9:1988, Direct acting indicating analogue electrical measuring instruments and theiraccessories – Part 9: Recommended test methodsIEC 60068-2-6:1995, Environmental tests – Part 2: Tests – Test Fc and guidance: Vibrations(sinusoidal)IEC 60068-2-27:1987, Environmental testing – Part 2: Tests – Test Ea and guidance: ShockIEC 60417:1973, Graphical symbols for use on equipment – Index, survey and compilation ofthe single sheetsIEC 60473:1974, Dimensions for panel-mounted indicating and recording electrical measuringinstruments*IEC 60617-2:1996, Graphical symbols for diagrams – Part 2: Symbol elements, qualifyingsymbols and other symbols having general applicationIEC 61010-1:1990, Safety requirements for electrical equipment for measurement, control, andlaboratory use – Part 1: General requirements2 DefinitionsThe values of a.c. quantities, given in this standard, are r.m.s. values unless otherwise stated.For the purpose of this standard, terms as defined in IEC 60050 apply, together with thefollowing additional terms.2.1 General terms2.1.1electrical measuring instrumenta measuring instrument intended to measure an electrical or non-electrical quantity usingelectrical means–––––––––––* Revision in preparationSIST EN 60051-1:2000

60051-1 © IEC:1997– 15 –2.1.2analogue display instrumenta measuring instrument intended to present or display the output information as a continuousfunction of the measured quantityNOTE – An instrument in which a change of the indication occurs by small discrete steps, but which does not havea digital display, is considered to be an analogue instrument.2.1.3indicating instrumenta measuring instrument which displays at any time the value of the measured quantity withoutrecording itNOTE – The indicated value may be different from the value of the quantity measured by the instrument and maybe in units of a different quantity.2.1.4direct acting indicating instrumentan instrument in which the indicating device is mechanically connected to and actuated by themoving element2.1.5electronic measuring instrumenta measuring instrument intended to measure an electrical or non-electrical quantity usingelectronic means2.1.6single function instrumentan instrument intended for the measurement of one kind of quantity only2.1.7multi-function instrumentan instrument having a single means of indication intended for the measurement of more thanone kind of quantity (e.g. an instrument measuring current, voltage and resistance)2.1.8fixed instrumentan instrument designed to be permanently mounted and which is intended to be connected to(an) external circuit(s) by means of permanently installed leads2.1.9portable instrumentan instrument specifically designed to be carried out by handNOTE – The instrument is intended to be connected and disconnected by the user.2.1.10polyphase instrumentan instrument for measurement in a polyphase system and arranged for connection to morethan one phase of the systemSIST EN 60051-1:2000

60051-1 © IEC:1997– 17 –2.1.11balanced load polyphase instrumenta polyphase instrument for use in a balanced polyphase system. This does not include asingle-phase wattmeter scaled in terms of polyphase power2.1.12instrument with magnetic screenan instrument shielded by ferro-magnetic material from the influence of a magnetic field ofexternal origin2.1.13astatic instrumentan instrument in which the measuring element is so constructed as to be unaffected by auniform magnetic field of external origin2.1.14instrument with electric screenan instrument shielded by conductive material from the influence of an electric field of externalorigin2.1.15accessoryan element group of elements or device associated with the measuring circuit of a measuringinstrument in order to confer specified characteristics to the measuring instrument2.1.15.1interchangeable accessoryan accessory having its own properties and accuracy, these being independent of those of theinstrument with which it may be associatedNOTE – An accessory is considered to be interchangeable when its rated characteristics are known and markedand are sufficient to enable its errors and variations to be determined without using the associated instrument. Ashunt whose adjustment takes into account an instrument current which is not negligible and which is known, isconsidered to be interchangeable.2.1.15.2accessory of limited interchangeabilityan accessory having its own properties and accuracy, which can only be associated withmeasuring instruments for which certain characteristics are within specified limits2.1.15.3non-interchangeable accessoryan accessory adjusted to take into account the electrical characteristics of a specific measuringinstrument2.1.16shunta resistor connected in parallel with a measuring circuit of a measuring instrumentNOTE – A shunt is generally intended to provide a voltage proportional to a current to be measured.SIST EN 60051-1:2000

60051-1 © IEC:1997– 19 –2.1.17series resistor (impedance)a resistor (impedance) connected in series with a measuring circuit of a measuring instrumentNOTE – A series resistor (impedance) is generally intended to extend the voltage measuring range of aninstrument.2.1.18instrument leada lead comprising one or more conductors, specially designed for interconnecting measuringinstruments to external circuits or to accessories2.1.19calibrated instrument leadan instrument lead whose resistance has a specified valueNOTE – A calibrated instrument lead is considered as being an interchangeable accessory of a measuringinstrument.2.1.20distortion factor (total harmonic distortion factor) (of a quantity)the ratio: r.m.s. value of the harmonic contentr.m.s. value of the non-sinusoidal quantity2.1.21ripple content of a quantitythe ratio: rms. value of the fluctuating componentvalue of the d.c. component2.1.22peak factorthe ratio of the peak value to the r.m.s. value of a periodic quantity2.2 Description of instruments according to their method of operation2.2.1permanent-magnet moving-coil instrumentan instrument which operates by the interaction of the magnetic field due to a current in amovable coil with the field of a fixed permanent magnetNOTE – The instrument can have more than one coil, measuring the sum or ratio of the currents in them.2.2.2moving-magnet instrumentan instrument which operates by the interaction of the field of a movable permanent magnetwith the magnetic field due to a current in a fixed coilNOTE – The instrument can have more than one coil.SIST EN 60051-1:2000

60051-1 © IEC:1997– 21 –2.2.3moving-iron instrumentan instrument which operates by the attraction between a movable piece of “soft" magneticmaterial and the field due to a current in a fixed coil or by the repulsion (and attraction)between one (or more) fixed piece(s) of “soft" magnetic material and a movable piece of “soft"magnetic material, both (all) magnetized by a current in a fixed coil2.2.4polarized moving-iron instrumentan instrument comprising a movable piece of "soft" magnetic material polarized by a fixedpermanent magnet and magnetically excited by a current in a fixed coil2.2.5electrodynamic instrumentan instrument which operates by the interaction of the magnetic field due to a current in amovable coil with the magnetic field due to a current in one or more fixed coils2.2.6ferrodynamic instrument (iron-cored electrodynamic instrument)an electrodynamic instrument in which the electrodynamic effect is modified by the presence of"soft" magnetic material in the magnetic circuit.2.2.7induction instrumentan instrument which operates by the interaction of the magnetic field(s) of (a) fixed a.c.electromagnet(s) with the magnetic field(s) due to currents which they induce in (a) movableconductive element(s)2.2.8thermal instrument (electrothermal instrument)an instrument which operates by the heating effect(s) of (a) current(s) m it(s) conductor(s)2.2.8.1bimetallic instrumenta thermal instrument in which the deformation of a bimetallic element (the materials havingdifferent rates of expansion due to a change in temperature), heated directly or indirectly by acurrent, produces the indication2.2.8.2thermocouple instrumenta thermal instrument making use of the e.m.f. of one or more thermocouples heated by thecurrent to be measuredNOTE – The e.m.f. is often measured using a permanent-magnet moving-coil instrument.2.2.9rectifier instrumentan instrument which is the combination of a measuring instrument sensitive to direct currentand a rectifying device whereby alternating currents or voltages may be measuredSIST EN 60051-1:2000

60051-1 © IEC:1997– 23 –2.2.10electrostatic instrumentan instrument the operation of which depends on the effects of electrostatic forces betweenfixed and movable electrodes2.2.11pointer-type frequency meteran instrument which indicates the measured frequency by the relationship between an indexand a scale2.2.12vibrating-reed frequency meteran instrument intended to measure frequency, comprising a set of tuned vibrating reeds, one ora few of which resonate under the action of an alternating current of the relevant frequencyflowing through one or more fixed coils2.2.13phase meteran instrument which indicates the phase angle between two electrical input quantities of thesame frequency and of similar waveformSuch an instrument measures:–the phase angle between a voltage and another voltage or between a current and anothercurrent,or–the phase angle between a voltage and a current.2.2.14power factor meteran instrument intended to measure the ratio between the active and the apparent power in anelectrical circuitIn practice, power factor meters indicate the cosine of the phase angle between a current and arelated voltage.2.2.15ratiometer (quotientmeter)an instrument for measuring the ratio (quotient) of two quantities2.2.16R.M.S.-responding instrumentan instrument which, over a specified frequency range, provides an indication which isdesigned to be proportional to the root-mean-square value of the measured quantity, evenwhen it is not sinusoidal or containing a d.c. part2.3 Constructional features of instruments2.3.1measuring circuit (of an instrument)the part of the electrical circuit internal to the instrument and its accessories, together with theinterconnecting leads, if any, which is energized by a voltage or a current, one or both of thesequantities being a prime factor in determining the indication of the measured quantity (one ofthese quantities may be the measured quantity itself)SIST EN 60051-1:2000

60051-1 © IEC:1997– 25 –2.3.1.1current circuita measuring circuit through which flows a current which is a prime factor in determining theindication of the measured quantityNOTE – It may be the current directly involved in the measurement or a proportional current supplied by an externalcurrent transformer or derived from an external shunt.2.3.1.2voltage circuita measuring circuit to which is applied a voltage which is a prime factor in determining theindication of a measured quantityNOTE – It may be the voltage directly involved in the measurement or a proportional voltage supplied by an externalvoltage transformer or an external voltage divider or derived by means of an external series resistor (impedance).2.3.2external measuring circuitthe part of the electrical circuit external to the instrument from which a measured value isobtained2.3.3auxiliary circuita circuit, other than a measuring circuit, required for the operation of the instrument2.3.3.1auxiliary supplyan auxiliary circuit which provides electrical energy2.3.4measuring elementthe assembly of those parts of a measuring instrument which are acted upon by a measuredquantity, resulting in a movement of the moving element related to that quantity2.3.5moving elementthe moving part of a measuring element2.3.6indicating devicethe part of a measuring instrument which displays values of the measured quantity2.3.7indexthe means which, in conjunction with the scale, indicates the position of the moving element ofan instrument2.3.8scalethe series of marks and numbers from which, in conjunction with the index, the value of themeasured quantity is obtainedSIST EN 60051-1:2000

60051-1 © IEC:1997– 27 –2.3.8.1scale marksmarks on the dial for the purpose of dividing it into suitable intervals so that the position of theindex may be determined2.3.8.2zero scale markthe mark on the dial associated with the figure zero2.3.8.3scale divisionthe distance between any two consecutive scale marks2.3.9scale numbersthe series of numbers which are associated with the scale marks2.3.10dialthe surface which carries the scale and other marks and symbols2.3.11mechanical zerothe equilibrium position which the index will approach when the measuring element (ifmechanically controlled) is de-energized. This may or may not coincide with the zero scalemark.In mechanically suppressed zero instruments, the mechanical zero does not correspond to ascale mark.In instruments without restoring torque the mechanical zero is indeterminate.2.3.11.1mechanical zero adjusterthe mechanism by means of which the instrument may be adjusted so that the mechanical zerocoincides with the appropriate scale mark2.3.11.2mechanical span adjusterthe mechanism by means of which the instrument may be adjusted so that the lower/upper limitof the measuring range coincides with the appropriate scale mark2.3.12electrical zerothe equilibrium position which the index will approach when the measured electrical quantity iseither zero or a set value and the control circuit (if any), producing a restoring torque, isenergizedSIST EN 60051-1:2000

60051-1 © IEC:1997– 29 –2.3.12.1electrical zero adjusterfor an instrument which needs an auxiliary supply, the mechanism by means of which theinstrument may be adjusted so that the electrical zero coincides with the appropriate scalemark2.3.12.2electrical span adjusterfor an instrument which needs an auxiliary supply, the mechanism by means of which theinstrument may be adjusted so that the lower/upper limit of the measuring range coincides withthe appropriate scale mark2.4 Characteristic features of instruments2.4.1scale lengththe length of the line (curved or straight) which passes through the centres of all the shortestscale marks contained between the first and the last scale marksIt is expressed in units of length.NOTE – If an instrument has more than one scale, each scale may have its own scale length. For convenience, thescale length of the instrument is taken to be that of the major scale.2.4.2spanthe algebraic difference between the upper and lower limits of the measuring rangeIt is expressed in units of the measured quantity.2.4.3measuring range (effective range)the range defined by two values of the measured quantity within which the limits of error of ameasuring instrument (and/or accessory) are specifiedNOTE – A measuring instrument (and/or accessory) can have several measuring ranges.2.4.4residual deflectionthe part of the deflection of a mechanically controlled moving element which remains after thecause producing it has disappeared and all the measuring circuits are de-energized2.4.5overshootthe difference between the extreme indication and the steady indication (expressed in terms ofthe scale length) when the measured quantity is abruptly changed from one steady value toanother2.4.6response timethe time taken for the indication to first reach and then remain within a band centred on thefinal steady indication when the measured quantity is abruptly changed from zero (theunenergized condition) to a value such that the final steady indication is a specified proportionof the scale lengthSIST EN 60051-1:2000

60051-1 © IEC:1997– 31 –2.5 Characteristic values2.5.1nominal valuea value of a quantity indicating the intended use of an instrument or accessory. The intendedcharacteristics of instruments and accessories are also nominal values2.5.2rated valuea value of a quantity assigned, generally by a manufacturer, for a specified operating condition2.5.3fiducial valuea clearly specified value of a quantity to which the error(s) of an instrument and/or anaccessory are referred in order to specify their respective accuraciesNOTE – This value can be, for example, the upper limit of the measuring range, the span or another clearly statedvalue.2.6 Influence quantity, reference conditions, nominal range of use and preconditioning2.6.1influence quantityany quantity, generally external to the measuring instrument and/or accessory, which mayaffect its performance2.6.2reference conditionsthe appropriate set of specified values and of specified ranges of values of influence quantitiesunder which the permissible errors of an instrument and/or an accessory are specifiedEach influence quantity may have either a reference value or a reference range.2.6.2.1reference valuea specified value of one of a set of reference conditions2.6.2.2reference rangea specified range of values of one of a set of reference conditions2.6.3nominal range of usea specified range of values which it is intended that an influence quantity can assume withoutcausing a variation exceeding the specified amountSIST EN 60051-1:2000

60051-1 © IEC:1997– 33 –2.6.4limiting values of an influence quantityextreme values which it is intended that an influence quantity can assume without theinstrument or accessory being damaged or permanently altered in such a way that it no longersatisfies the requirements of its accuracy classNOTE – The limiting values may depend on the duration of their application2.6.5preconditioningthe action whereby a specified value of the measured quantity is applied to the measuringcircuit prior to carrying out testing or use of the instrument or accessory2.7 Errors and variations2.7.1(absolute) errorfor an instrument, the value obtained by subtracting the true value from the indicated valuefor an accessory, the value obtained by subtracting the true value from the marked (intended)valueNOTE 1Since the true value cannot be obtained by measurement, a value obtained under specified test conditionsand at a specified time is used instead. This value is derived from national measurement standards ormeasurement standards agreed upon by the manufacturer and the user.NOTE 2Attention is drawn to the fact that an error of an accessory may be transformed into an error of theopposite sign when the accessory is used with an instrument.2.7.2intrinsic errorthe error of an instrument and/or accessory when under reference conditions2.7.3tracking errorthe difference between the indication of a measuring instrument and the proportional value ofthe measured quantity at points within the scale, the instrument having been previously set tohave no error at two points2.7.4variationthe difference between the two indicated values for the same value of the measured quantity ofan instrument or the two true values of an accessory when a single influence quantity assumessuccessively two different specified values within the nominal range of use2.8 Accuracy, accuracy class and class index2.8.1accuracyfor a measuring instrument, the quality which characterizes the closeness of the indicatedvalue to the true valuefor an accessory, the quality which characterizes the closeness of the marked (intended) valueto the true valueNOTE – The accuracy of a measuring instrument or of an accessory is defined by the limits of intrinsic error end bythe limits of variations.SIST EN 60051-1:2000

60051-1 © IEC:1997– 35 –2.8.2accuracy classa group of measuring instruments and/or accessories which meet certain metrologicalrequirements intended to keep permissible errors and variations within specified limits2.8.3class indexthe number which designates the accuracy classNOTE – Some instruments and/or accessories may have more than one class index.3 Description, classification and compliance3.1 DescriptionInstruments and/or accessories shall be described according to their method of operation ortheir nature as given in clause 2 and/or by their special characteristics as given in the relevantparts.3.2 ClassificationClass indices shall be selected from a 1-2-5 sequence and the decimal multiples andsubmultiples thereof.In addition, class indices 0,3, 1,5, 2,5 and 3 may be used for instruments, class index 0,15 forfrequency meters and class index 0,3 for accessories.3.3 Compliance with the requirements of this standardInstruments and accessories marked with a class index shall comply with the relevantrequirements of this standard relating to their class index.The recommended test methods for checking compliance with the requirements of thisstandard are given in IEC 60051-9.In case of dispute, the test methods of IEC 60051-9 are referee methods.3.3.1
If, for the determination of intrinsic errors preconditioning is specified, the manufacturershall state the preconditioning period and the value(s) of the measured quantity(ies). Thepreconditioning period shall not exceed 30 min.3.3.2
Instruments and accessories shall be adequately packed to ensure that, after transportto the user, under normal conditions, they comply with the requirements of this standardrelating to their class index.4 Reference conditions and intrinsic errors4.1 Reference conditions4.1.1
The reference values of the influence quantities shall be as given in table I-1.SIST EN 60051-1:2000

60051-1 © IEC:1997– 37 –4.1.2
The reference value for the ambient temperature shall be selected from 20 °C, 23 °Cor 27 °C.4.1.3
Reference conditions different from those given in table I-1 may be specified, but theyshall then be marked in accordance with clause 8.4.2 Limits of intrinsic error, fiducial valueWhen the instrument together with its non-interchangeable accessory(ies) (if any) or accessoryis under the reference condition given in table I-1 and is used between the limits of itsmeasuring range and in accordance with the manufacturer's instructions, the intrinsic error,expressed as a percentage of the fiducial value*, shall not exceed the limits appropriate to itsaccuracy class. Values stated in a table of corrections supplied with the instrument oraccessory shall not be taken into account in determining the errors.NOTE 1The intrinsic error includes other errors such as those due to friction, amplifier drift, etc.NOTE 2The accuracy classes relating to each type of instrument or accessory are given in the appropriate parts(clause 3).4.2.1 Correspondence between intrinsic error and accuracy classThe maximum permissible error is related to the accuracy class such that the class index isused as the limit of error, expressed as a percentage with positive and negative signs.NOTE – For example, for a class index of 0,05, the limits of intrinsic error are ±0,05 % of the fiducial value.–––––––––––* This is the fiducial error. See term 301-08-08 of IEC 60050(301), (302), (303).SIST EN 60051-1:2000

60051-1 © IEC:1997– 39 –Table I-1 – Reference conditions and tolerances for testing purposes relatingto the influence quantitiesInfluence quantityReference conditionsTolerances permitted for testingpurposes, applicable for a singlereference value 1)unless otherwise markedClass indices0,3 and smallerClass indices0,5 and greaterAmbient temperature23 °C±1 °C±2 °CHumidityRelative humidity40 % to 60 %––Ripple of d.c. measured quantityRipple content zeroRipple content1 %Ripple content3 %Distortion of a.c.measuredquantityDistortion factorZero1Rectifier instruments, non r.m.s.-responding electronic instrumentsand instruments which employphase-shifting networks in theirmeasuring circuits: distortionfactor less than or equal to halfthe class index or 1 % whicheveris smaller.2Other instruments: distortion factornot exceeding 5 %Peak factor2,approx. 1,414 (sine wave)±0,05Frequency of a.c. measured quantityexcept for wattmeters, varmeters,frequency meters and power factormeters45 Hz to 65 Hz±2 % of the reference value or ±110of the reference range for frequency(if any), whichever is the smallerPosition 2)Fixed instruments:mounting plane verticalPortable instruments:mounting plane horizontal±1°Nature andthickness ofpanel or supportF-37F-38F-39 3)NoneNatureFerrousFerrousNon-ferrousAnyThicknessX mmAnyAnyAny±0,1 X mm or ±0,5 mm, whichever is–smaller––Magnetic field of external originTotal absence40 A/m* at frequencies from d.c. to65 Hz in any directionElectric field of external originTotal absence1 kV/m at frequencies from d.c. to65 Hz in any direction(See notes on page 41)SIST EN 60051-1:2000

60051-1 © IEC:1997– 41 –Table I-1 (continued)Influence quantityReference conditionsunless otherwise markedTolerances permitted for testingpurposes, applicable for a singlereference value 1)AuxiliaryVoltageNominal value or nominal range±5 % of the nominal value 4)supplyFrequencyNominal value or nominal range±1 % of the nominal value 4)*40 A/m is approximately the highest value of the Earth’s magnetic field.1)These tolerances apply when a single reference value is specified in this table or is marked by themanufacturer. For a reference range, no tolerance is allowed.2)Instruments provided with a level indicator shall be tested with the instrument set level using the level indicator.3)These symbols (or lack of symbol) refer to the nature and thickness of the panel or support on which theinstrument is mounted. See table III-1.4)Unless a different tolerance is stated by the manufacturer.4.2.2 Fiducial valueThe fiducial value for each type of instrument and accessory is given in each relevant part.5 Nominal range of use and variations(See annex B-1.)5.1 Nominal range of use5.1.1
The limits of the nominal range of use for influence quantities shall be as given intable II-1.5.1.2
When a manufacturer assigns and marks a nominal range of use which is different fromthat shown in table II-1, it shall include the reference range (or reference value with permittedtolerances) and will normally exceed it in at least one direction.5.1.2.1
For values in the nominal range of use beyond the reference range (or referencevalue), the permissible variation is as stated in table II-1.Example: For an instrument having a class index of 0,2, the variation due to a lack of level of5° in any direction shall not exceed:0,2 (%) ´ 50100 = 0,1 % of the fiducial value.5.1.2.2
When the influence quantity is not one of those shown in table II-1, the relevantpermissible variation shall be stated by the manufacturer and shall not exceed 100 % of theclass index.SIST EN 60051-1:2000

60051-1 © IEC:1997– 43 –5.2 Limits of variationsWhen an instrument or an accessory is under reference conditions and a single influencequantity is varied, the variation shall not exceed the values given in table II-1 and in 5.2.1, 5.2.2and 5.2.3.Table II-1 – Limits of the nominal range of use and permissible variationsInfluence quantityLimits of the nominal range of useunless otherwise markedPermissiblevariationexpressed as apercentage ofthe class indexFor therecommendedtests, seeIEC 60051-9,subclause:Ambient temperatureReference temperature ±10 °C orlower limit of reference range –10 °Cand upper limit of reference range+10 °C100 %3.2HumidityRelative humidity 25 % and 80 %100 %3.3Ripple on d.c. measured quantitySee relevant parts3.6Distortion of a.c. measured quantityDistortion factor: see relevant parts3.7Peak factor: see relevant partsUnderconsiderationFrequency on a.c. measuredquantitySee relevant parts3.8Position 1)Horizontal and vertical if thereference position is not marked100 %3.45° in any direction from referenceposition50 %Magnetic field of external originSee 5.2.1 and the relevant parts3.5Electric field of external origin(electrostatic instruments only)20 kV/m at d.c. and 45 Hz to 65 Hz.See 5.2.2.100 %3.14AuxiliaryVoltageReference value ±10 % or lower limitof reference range –10 % and upperlimit of reference range +10 %50 %3.17supplyFrequencyReference value ±5 % or lower limitof reference range –5 % and upperlimit of reference range +5 %50 %3.181)Instruments provided with a level indicator shall always be set correctly for position using the level indicator.These instruments need not therefore be tested for variation due to position.5.2.1 Variation due to a magnetic field of external origin5.2.1.1
When the instrument is not marked with symbol F-30 (table III-1), the magnetic fieldstrength in the test equipment shall be 0,4 kA/m.5.2.1.2
For instruments marked with symbol F-30 (table III-1), the magnetic field strength inthe test equipment shall have a value in kiloamperes per metre as shown in the symbol.SIST EN 60051-1:2000

60051-1 © IEC:1997– 45 –5.2.1.3
Under the conditions of 5.2.1.1 and 5.2.1.2, the variation shall not exceed the limitsgiven in table II of the relevant parts.5.2.2 Variation due to an electric field of external origin (electrostatic instruments only)The variation due to an electric field of external origin at d.c. and 45 Hz to 65 Hz, having astrength of 20 kV/m and under the most unfavourable conditions of phase and orientation, shallnot exceed 100 % of the class index.If the instrument is marked with symbol F-34 (table III-1), the field strength is made equal tothe value given in the symbol.5.2.3 Variation due to ferromagnetic supportsThe error of instruments which are mounted on a panel of the nature and thickness implied bythe relevant symbol F-37, F-38 or F-39 or on a panel of any nature and thickness when not somarked - shall remain within the limits of the intrinsic error.For the recommended test, see 3.1 of IEC 60051-9.5.2.4 Variation due to conductive supportsFor the recommended test, see 3.13 of IEC 60051-9.Instruments shall meet the requirements for intrinsic errors relating to their class index whenused on a panel or support of high conductivity unless other requirements are given in aseparate document and are shown by marking with symbol F-33 (table III-1).5.3 Conditions for the determination of va
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